1. science
2. physics

arXiv:1410.2566v1 [hep-ex] 9 Oct 2014
Latest Results of the OSQAR Photon Regeneration Experiment for Axion-Like Particle Search
Rafik Ballou1,2 , Guy Deferne3 , Lionel Duvillaret4 , Michael Finger, Jr.5 , Miroslav Finger5 ,
Lucie Flekova5 , Jan Hosek6 , Tomas Husek5 , Vladimir Jary6 , Remy Jost7,8 , Miroslav Kral6 ,
Stepan Kunc9 , Karolina Macuchova6 , Krzysztof A. Meissner10 , J´erˆome Morville11,12 , Pierre
Pugnat13,14 , Daniele Romanini7,8 , Matthias Schott15 , Andrzej Siemko3 , Miloslav Slunecka5 ,
Miroslav Sulc9 , Guy Vitrant4 , Christoph Weinsheimer15 , Josef Zicha6
1
CNRS, Institut N´eel, F-38042 Grenoble, France
Universit´e Grenoble Alpes, Institut N´eel, F-38042 Grenoble, France
3
CERN, CH-1211 Geneva-23, Switzerland
4
Grenoble INP - Minatec & CNRS, IMEP-LAHC, F-38016 Grenoble, France
5
Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
6
Czech Technical University, Prague, Czech Republic
7
Universit´e Grenoble Alpes, LIPhy, F-38000 Grenoble, France
8
CNRS, LIPhy, F-38000 Grenoble, France
9
Technical University of Liberec, 46117 Liberec, Czech Republic
10
University of Warsaw, Institute of Theoretical Physics, 00-681 Warsaw, Poland
11
Universit´e Claude Bernard Lyon-1, Institut Lumi`ere Mati`ere, F-69622 Villeurbanne, France
12
CNRS, Institut Lumi`ere Mati`ere, F-69622 Villeurbanne, France
13
CNRS, LNCMI, F-38042 Grenoble, France
14
Universit´e Grenoble Alpes, LNCMI, F-38042 Grenoble, France
15
University of Mainz, Institute of Physics, 55128 Mainz, Germany
2
DOI: will be assigned
The OSQAR photon regeneration experiment searches for pseudoscalar and scalar axionlike particles by the method of “Light Shining Through a Wall”, based on the assumption
that these weakly interacting sub-eV particles couple to two photons to give rise to quantum
oscillations with optical photons in strong magnetic field. No excess of events has been
observed, which constrains the di-photon coupling strength of both pseudoscalar and scalar
particles down to 5.7 · 10−8 GeV−1 in the massless limit. This result is the most stringent
constraint on the di-photon coupling strength ever achieved in laboratory experiments.
1
Introduction
Embedding the Standard Model (SM) of particle physics into more general unified theories often
results in postulating new elementary particles in unexplored parameter space. A number of
weakly interacting sub-eV particles (WISPs) are thus predicted besides the weakly interacting
massive particles (WIMPs). The most prominent example of WISPs is the axion [1], first
anticipated from the breaking at the quantum level of an additional U (1)P Q global symmetry
Patras 2014
1
arXiv:1410.2377v1 [astro-ph.IM] 9 Oct 2014
PoGOLino: a scintillator-based balloon-borne neutron
detector
Merlin Kolea,b,∗, Maxime Chauvina,b , Yasushi Fukazawac , Kentaro Fukudad ,
Sumito Ishizud , Miranda Jacksona,b , Tune Kamaee , Noriaki Kawaguchid ,
Takafumi Kawanoc , M´ozsi Kissa,b , Elena Morettia,b , Mark Pearcea,b , Stefan
Rydstr¨oma,b , Hiromitsu Takahashic , Takayuki Yanagidaf
a
KTH Royal Institute of Technology, Department of Physics, 106 91 Stockholm, Sweden
The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106
91 Stockholm, Sweden
c
Department of Physical Science, Hiroshima University, Hiroshima 739-8526, Japan
d
Tokuyama Corporation, Shunan, Yamaguchi, Japan
e
University of Tokyo, Deptartment of Physics, 113-0033 Tokyo, Japan
f
Kyushu Institute of Technology, Kitakyushu, Fukuoka, Japan
b
Abstract
PoGOLino is a balloon-borne scintillator-based experiment developed to
study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors that make use
of LiCAF, a novel neutron sensitive scintillator, sandwiched by BGO crystals
for background reduction. The experiment was launched on March 20th 2013
from the Esrange Space Centre, Northern Sweden (geomagnetic latitude of
65◦ ), for a three hour flight during which the instrument took data up to an
altitude of 30.9 km. The detector design and ground calibration results are
presented together with the measurement results from the balloon flight.
Keywords: Neutron detection, Balloon-borne, Astroparticle physics,
Phoswich scintillator, LiCAF
∗
Corresponding author. Tel.: +46 85 537 8186 ; fax: +46 85 537 8216. E-mail address:
[email protected]
Preprint submitted to Nuclear Instruments and Methods in Physics Research A October 10, 2014
Gravitational Wave Detection with High Frequency Phonon Trapping Acoustic
Cavities
Maxim Goryachev1 and Michael E. Tobar1, ∗
arXiv:1410.2334v1 [gr-qc] 9 Oct 2014
1
ARC Centre of Excellence for Engineered Quantum Systems,
School of Physics, University of Western Australia,
35 Stirling Highway, Crawley WA 6009, Australia
(Dated: October 10, 2014)
There are a number of theoretical predictions for astrophysical and cosmological objects, which
emit high frequency (106 −109 Hz) Gravitation Waves (GW) or contribute somehow to the stochastic
high frequency GW background. Here we propose a new sensitive detector in this frequency band,
which is based on existing cryogenic ultra-high quality factor quartz Bulk Acoustic Wave cavity
technology, coupled to near-quantum-limited
SQUID amplifiers at 20 mK. We show that spectral
√
strain sensitivities reaching 10−22 per Hz per mode is possible, which in principle can cover the
frequency range with multiple (> 100) modes with quality factors varying between 106 − 1010
allowing wide bandwidth detection. Due to its compactness and well established manufacturing
process, the system is easily scalable into arrays and distributed networks that can also impact the
overall sensitivity and introduce coincidence analysis to ensure no false detections.
INTRODUCTION
Gravitational radiation was first predicted by
Einstein[1] as a consequence of his General Theory of
Relativity. Gravitational waves (GW) are the propagation of a wave of space-time curvature, and are generated
by perturbations in massive systems. The lowest multipole of this type of radiation is the quadrupole. Even
though astrophysical events are expected to emit massive
energy fluxes in the form of gravitational radiation, they
are yet to be directly detected. This is because gravity
waves interact very weakly with matter. However,
for many decades experimentalists have been pushing
the limits of technology. Currently the free-mass laser
interferometer detectors have been improved to a point,
where they are expected to directly detect gravitational
waves in the 0.1 to 1 kHz frequency band through the
development of advanced LIGO[2].
The first gravitational wave detectors were based on
the ”Weber Bar”, and required the monitoring of a
high-Q massive resonant system (resonant-mass detector). Such a system will change its state of vibration
due to an incident gravitational wave of matched frequency and rely on ultra-sensitive transducers to readout the vibration. These transducers detect the displacement change of the system and convert it to an
electronic signal. Since the first detector was built[3]
technology improved rapidly over the years, with major
projects in Italy, USA and Australia[4]. These detectors
necessarily operated at low temperatures, and were successfully built at high sensitivity operating at 5 K down
to 100 mK. The original transducers that Weber used
were based on piezoelectricity, and later gap modulated
displacement sensors were developed based on SQUID
readouts[5] and low noise parametric systems[6]. These
∗
[email protected]
devices were optimised to detect millisecond bursts, typically produced by Supernovas with strain sensitivities of
order h1ms > 10−18 (or signal strain Fourier component
H > 10−21 strain/Hz), but have generally been superseded by the laser interferometer detectors[7–9].
In this work we aim to revive the resonant-mass detector for the first cosmic search of high frequency gravitational wave radiation based on piezoelectric quartz
Bulk Acoustic Wave (BAW) resonators. Despite dominance of the low frequency GW detection, this technology opens the way to test for known and unknown high
frequency sources[10, 11]. Indeed, many theoretical models predict the high frequency gravitational wave background over a broad range of frequencies up to 1010 Hz.
Such experiments could be interesting from two points of
view: first, the high frequency region has physically understood processes of generation of GWs, second, such
experiments can be regarded as tests for many emerging theories predicting GW radiation at such frequencies.
The former mostly includes phenomena associated with
discrete sources such as thermal gravitational radiation
from stars[11], radiation from low mass primordial black
holes[12–14], gravitational modes of plasma flows[15],
while the latter group is built up by cosmological sources
including stochastic sources in the early universe[16], GW
background from quintessential inflation[17, 18], cosmic
strings[19, 20], dilation[21], pre-Big Bang scenarios[22],
superinflation in loop quantum gravity[23], post inflationary phase transitions[24], parametric resonance at
the end of inflation or preheating[25–27] and other predicted objects like brane-world black holes associated
with extra dimensions[28, 29] or clouds of axions[30].
Sensitive tests now become possible due to recent work
on quartz bulk acoustic wave (BAW) resonators, which
have been cooled to below 20 mK with outstanding
acoustic properties[31–34]. Also, they have proven to
be compatible with SQUID amplifiers and offer quantum limited amplification at mK temperatures[35, 36].
The modes in these devices are naturally sensitive to
Signal Formation in a Detector with one Large Dimension
Manolis Dris
arXiv:1410.2532v1 [physics.ins-det] 9 Oct 2014
National Technical University of Athens, Department of Physics,
9 Heroon Polytechniou Street, GR 157 80, Athens, Greece
October 10, 2014
Abstract
We present the theory for the signal formation in a multi conductor detector with cylindrical geometry and long
length. There exists electromagnetic wave propagation along the large dimension of the detector. The system is
equivalent to a multi conductor transmission line. The treatment is in the TEM approximation. Each conductor is
fed by its current source which is the same as in the case of small size detectors. A simple example is given for a
long length Monitored Drift Tube (MDT). One could apply the result to a long micromegas-type detector or any
long microstrip detector, ignoring propagation that is transverse to the strips.
Contents
1 Signal formation in a detector with cylindrical geometry and long length
1
2 Example: Long cylindrical detector of circular cross-section with a wire along its axis
20
3 Conclusions
21
1
Signal formation in a detector with cylindrical geometry and long
length
The problem of induced currents on conducting electrodes due to the motion of electrons in between the electrodes’
vacuum space, dates back to the 1930’s and 1940’s . At that time various types of vacuum tube devices were in use
and such effects were important at high enough frequencies, when the electron time of flight between the electrodes
was comparable to the period of the radiofrequencies involved (see the classic papers by W. Shockley [1] and by S.
Ramo [2]). Following similar techniques, the problem of signal formation in particle detectors is analysed in several
papers and books, [3, 4, 5, 6, 7]. In all cases, small size detectors is ussumed, since electrostatics is used with no
electromagnetic wave propagation. There are applications of the above techniques for the case of long length detectors
where wave propagation exists along the detector length, as in [8]. As far as we know, no rigorous justification exists
for doing so. In this work we give a rigorous proof of what happens for loong length detectors.
The cylindrical geometry of the detector is shown in Fig. 1 and Fig. 2. We will start by examining an ideal
detector which consists of many parallel conductors without resistance. The criterion for a material to be a very good
conductor, is the relaxation time τ = /σ (i.e. permittivity divided by conductivity) to be much smaller than the
periods (T = 1/f ) of the waves involved. If the opposite is true, then the material behaves more like a dielectric.
Between the two extremes one has dielectric materials with conductivity.
First we assume the space between the conductors contains a homogeneous linear dielectric medium whose permittivity
does not depend on frequency, i.e. = r 0 = constant. The medium could be a gas. The motion of a charge in
the space between the ideal conductors, excites the system and as a result signals are formed and propagate to the
ends of the conductors, where they are detected by the external circuits connected. We examine an ideal case without
any dielectric ”losses”. This means there is no any conduction (transverse) current in the dielectric and there are no
dielectric polarization losses.
1
arXiv:1410.2439v1 [physics.ins-det] 9 Oct 2014
Progress in Development of Silica Aerogel for Particle- and
Nuclear-Physics Experiments at J-PARC
Makoto Tabata∗ and Hideyuki Kawai
Department of Physics, Chiba University, Chiba, Japan
E-mail: [email protected]
This study presents the advancement in hydrophobic silica aerogel development for use as Cherenkov
radiators and muonium production targets. These devices are scheduled for use in several particleand nuclear-physics experiments that are planned in the near future at the Japan Proton Accelerator
Research Complex. Our conventional method to produce aerogel tiles with an intermediate index
of refraction of approximately 1.05 is extended so that we can now produce aerogel tiles with lower
indices of refraction (i.e., 1.03–1.04) and higher indices of refraction (i.e., 1.075–1.08); each with excellent transparency. A new production method, called pin drying, was optimized to produce larger
area aerogels consistently with an ultrahigh index of refraction (>1.10). In addition, for use as a
thermal-muonium-emitting material at room temperature, dedicated low-density aerogels were fabricated using the conventional method.
KEYWORDS: silica aerogel, refractive index, pin drying, Cherenkov radiator, muonium
production target, J-PARC
1. Introduction
Silica aerogel is a highly porous solid of silicon dioxide and is synthesized by the sol–gel method.
In general, it is optically transparent; however, the transparency depends strongly on how it is produced. When we use aerogels as radiators in Cherenkov counters, the aerogel transparency is an
important parameter for detector performance. An aerogel’s transparency is parameterized by the
transmission length ΛT (λ) = −t/lnT (λ), where λ is the wavelength of the emitted light, t is the aerogel
thickness, and T (λ) is the transmittance measured with a spectrophotometer [1]. Another characteristic of the aerogel is its index of refraction n, which is determined by the silica–air volume ratio and
is tunable over a given range, as discussed below. The bulk density is also a useful aerogel parameter
for certain applications; e.g., as a medium to capture hypervelocity comic dusts intactly. An empirical
relationship exists between the index of refraction and the density ρ: n(λ) − 1 = k(λ)ρ, where k(λ)
is a constant that depends on the wavelength of light and on the fine structure of the aerogel (i.e., its
production method) [1].
In Japan, by the end of the 1990s, aerogels with a range of 1.01 to 1.03 were well studied and
had long transmission lengths [2]. These aerogels were mass produced using the classic KEK method
described in Refs. [3, 4] and were used in the aerogel Cherenkov counters [4, 5] of the Belle experiment [6] at the High Energy Accelerator Research Organization (KEK). At that time, the classic
method allowed us to produce aerogels with a maximum index of refraction of 1.10; however, for
practical use, the transmission length had to be improved. In addition, it was impossible to produce
aerogels with n > 1.14 with the sol–gel method [1]. For low indices of refraction, aerogels with n =
1.008 (density of 0.03 g/cm3 ) were used for capturing cosmic dust at low earth orbit in the MicroParticles Capturer (MPAC) experiment implemented by the Japan Aerospace Exploration Agency
aboard the International Space Station (e.g., Ref. [7]). However, producing and handling aerogels
High-performance controllable ambipolar infrared
phototransistors based on graphene-quantum dot hybrid
Ran Wang1, 2, Yating Zhang1, 2, *, Haiyang Wang1, 2, Xiaoxian Song1, 2, Lufan Jin1, 2, Haitao Dai3,
Sen Wu1 ,and Jianquan Yao1, 2
1
Institute of Laser & Opto-Electronics, College of Precision Instruments and Opto-electronics
Engineering, Tianjin University, Tianjin 300072, China
2
Key Laboratory of Opto-electronics Information Technology (Tianjin University), Ministry of
Education, Tianjin 300072, China
3
Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of
Science, Tianjin University, Tianjin 300072, China
Corresponding author: [email protected]
The field effect transistors (FETs) exhibited ultrahigh responsivity (107 A/W) to
infrared light with great improvement of mobility in graphene / PbS quantum
dot (QD) hybrid. These reported transistors are either unipolar or depletion
mode devices. In this paper, we presented and fabricated conveniently-controlled
grapheme / PbS QD hybrid FETs. Through the investigation on electric and
optoelectronic properties, the ambipolar FETs (normally OFF) can be switched
ON by raising gate voltage (VG) up to 3.7 V and -0.8 V in the first and third
quadrants. Near these thresholds (VT) each carrier species shows comparable
mobility (~ 300 cm2V-1s-1). Photo-responsivity reach ~ 107 A/W near each
threshold and it will linearly increases with (VG-VT). These hybrid FETs become
strongly competitive candidates for devices in flexible integrated circuits with
low cost, large area, low-energy consumption and high performances.
Recently, a breakthrough of graphene-quantum dot hybrid field effect transistor (FET)
in photo-responsivity has attracted much attention [1, 2]. Taking advantages of the
extreme high mobility of graphene and strong light-absorbing properties of PbS
quantum dots (QDs), hybrid metal oxide semiconductor field effect transistors
(MOSFETs) exhibit excellent performance in photo-responsivity and gain [1, 2]. The
reported responsivities are as high as 107 AW-1, while the gain up to 108, which is at
least seven order of magnitude larger than graphene FETs or QD FETs that had been
reported before [3-10]. The sensitivity and spectral selectivity can be tuned by altering
Sub to Chinese Physics C
Vol. XX, No. X, Xxx, 201X
A digital CDS technique and the performance testing *
arXiv:1410.2402v1 [physics.ins-det] 9 Oct 2014
LIU Xiao-Yan1,2
WANG Yu-Sa2
LI Mao-Shun2
XU Yu-Peng2
WANG Juan2
HUO Jia2
ZHANG Zi-Liang2
Fu Yan-Hong2,3
2
LU Jing-Bin1
HU Wei2
LU Bo2
CUI Wei-Wei2
LI Wei2
HAN Da-Wei2
ZHANG Yi2
YIN Guo-He2
Zhang Ya2,3
YANG Yan-Ji1,2
Wang Yu2
MA Ke-Yan1
CHEN Tian-Xiang2
ZHU Yue2
Zhao Zhong-Yi2,3
CHEN Yong2;1)
1 College of Physics, Jilin University, No.2699, Qianjin Road, Changchun 130023, China
Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences (CAS), 19B Yuquan
Road, Beijing 100049, China
3 School of Physical Science and Technology, Yunnan University, Cuihu North Road 2, Kunming, 650091, China
Abstract Readout noise is a critical parameter for characterizing the performance of charge-coupled devices
(CCDs), which can be greatly reduced by the correlated double sampling (CDS) circuit. However, conventional
CDS circuit inevitably introduces new noises since it consists of several active analog components such as
operational amplifiers. This paper proposes a digital CDS circuit technique, which transforms the pre-amplified
CCD signal into a train of digital presentations by a high-speed data acquisition card directly without the noisy
CDS circuit first, then implement the digital CDS algorithm through numerical method. The readout noise of
3.3 e− and the energy resolution of 121 [email protected] can be achieved via the digital CDS technique.
Key words charge-coupled devices, readout noise, correlated double sampling
PACS 29.30.Kv, 29.40.Wk, 29.85.-c
1
Introduction
Owing to its advantages on smaller size, lower
power dissipation, wider response spectrum range,
lower noise and higher resolution, Charge-coupled devices (CCDs) have been widely applied in industrial
inspection, night vision, visible imaging, soft X-ray
astronomical observations and so on. As a critical
parameter that has to be considered in designing and
operating CCD, the noises of CCD mainly come from
two mechanisms, one comes from CCD itself, including shot noise, dark current noise and the transfer
noise[1], and the other comes from the operation of
CCD, such as output amplifier noise and the reset
noise.
It is common to suppress the reset noise with the
correlated double sampling (CDS) circuit. However,
traditional CDS introduces new noises, and leaves
some useful information behind, e.g. the original
waveform. The digital CDS, e.g. Gach J L, 2003[2],
is able to store all the initial information, which provides the possibility for varies of the backend data
process. In practice, it shows a perfect performance
on the reduction of the readout noise.
In this paper, a digital correlated double sampling
circuit technique is proposed. A PCI-9846H data acquisition card, which is manufactured by ADLINK
Inc., has been used to convert the pre-amplified CCD
signal into the digital representations. The digital
CDS system can record a large amount of data and
the original waveform could be derived from these
data for further analyzing of the signal characteristics. So the data processing could be optimized to
get better performance such as a lower readout noise.
The relationship between the readout noise of the digital CDS system and the sample number has been in-
∗ Partially supported by National Natural Science Foundation of China (10978002)
1) E-mail: [email protected]
c 2013 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute
of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd
Charmless hadronic B → (f1 (1285), f1(1420))P decays in the perturbative QCD approach
Xin Liu1a , Zhen-Jun Xiao2b , Jing-Wu Li1c , and Zhi-Tian Zou3d
arXiv:1410.2345v1 [hep-ph] 9 Oct 2014
1
School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, Jiangsu 221116, People’s Republic of China
2
Department of Physics and Institute of Theoretical Physics,
Nanjing Normal University, Nanjing, Jiangsu 210023, People’s Republic of China
3
Department of Physics, Yantai University, Yantai, Shandong 264005, People’s Republic of China
(Dated: October 10, 2014)
We study twenty charmless hadronic B → f1 P decays, with B denoting Bu , Bd , and Bs mesons, P standing for the light pseudoscalar mesons, and f1 representing axial-vector mesons f1 (1285) and f1 (1420) that
¯√ d¯
resulting from a mixing of quark-flavor f1q [ uu+d
] and f1s [s¯
s] states with the angle φf1 , in the perturbative
2
QCD(pQCD) formalism. The estimations of CP-averaged branching ratios and CP asymmetries of the considered B → f1 P decays, in which the Bs → f1 P modes are investigated for the first time, are presented
in the pQCD approach with φf1 ∼ 24◦ from recently measured Bd/s → J/ψf1 (1285) decays. It is found
that (a) the tree dominant B + → f1 π + and the penguin dominant B + → f1 K + decays with large branching
ratios[O(10−6 )] and large direct CP violations(around 14% ∼ 28% in magnitude) simultaneously are believed
to be clearly measurable at the LHCb and Super-B factory experiments; (b) the nearly pure penguin-dominated
Bd → f1 KS0 and Bs → f1 (η, η ′ ) modes with safely negligible tree pollution also have large decay rates in
the order of 10−6 ∼ 10−5 , which can be confronted with the experimental measurements in the near future;
(c) as the alternative channels, the B + → f1 (π + , K + ) and Bd → f1 KS0 decays have the supplementary
power in providing more effective constraints on the Cabibbo-Kobayashi-Maskawa weak phases α, γ, and β
correspondingly, which are explicitly analyzed through the large decay rates and the direct and mixing-induced
CP asymmetries in the pQCD approach and are expected to be stringently examined by the measurements
with high precision; (d) the weak annihilation amplitudes play important roles in the B + → f1 (1420)K + ,
Bd → f1 (1420)KS0 , Bs → f1 (1420)η ′ decays and so on, which would offer more evidences, once they are
confirmed by the experiments, to identify the soft-collinear effective theory and the pQCD approach on the
evaluations of annihilation diagrams and to help further understand the annihilation mechanism in the heavy B
meson decays; (e) combined with the future precise tests, the considered decays can provide more information
to further understand the mixing angle φf1 and the nature of the f1 mesons in depth after the confirmations on
the reliability of the pQCD calculations in the present work.
PACS numbers: 13.25.Hw, 12.38.Bx, 14.40.Nd
I.
INTRODUCTION
It is well known that non-leptonic weak decays of heavy B(specifically, Bu , Bd , Bs and Bc ) mesons can not only provide
the important information to search for CP violation and further constrain the Cabibbo-Kobayashi-Maskawa(CKM) parameters
in the standard model(SM), but also reveal the deviations from the SM, i.e., the signals of exotic new physics beyond the
SM. Furthermore, comparison of theoretical predictions and experimental data for the physical observables may also help us
understand the hadronic structure of the involved bound states deeply. In contrast to the traditional B → P P, P V and V V
decays, the alternative channels such as B → AP (A: axial-vector mesons) decays to be largely detected at the experiments
in the near future may give the additional and complementary information on exclusive non-leptonic weak decays of heavy B
mesons [1], e.g. due to Vtb∗ Vts = −Vcb∗ Vcs [1 + O(λ2 )], the b → sq q¯ penguin-dominated decays have the same CKM phase as
the b → c¯
cs tree level decays [2]. Therefore, the b → sq q¯ mediated B → AP decays such as B 0 → a1 (1260)(b1 (1235))KS0
πK1 (1270)[K1(1400)], f1 KS0 etc. can provide sin 2β(β: CKM weak phase) measurements in the SM complementarily.
Very recently, the Large Hadron Collider beauty(LHCb) Collaboration reported the first measurements of Bd/s → J/ψf1 (1285)
decays [3], where the final state f1 (1285) was observed for the first time in heavy B meson decays. In the conventional two
quark structure, f1 (1285) and its partner f1 (1420) [4, 5](Hereafter, for the sake of simplicity, we will use f1 to denote both
f1 (1285) and f1 (1420) unless otherwise stated.) are considered as the orbital excitation of q q¯ system, specifically, the light pwave axial-vector flavorless mesons. In terms of the spectroscopic notation (2S+1) LJ with J, L, and S the total, orbital, and spin
angular momenta in q q¯ system, respectively, both f1 mesons belong to 3P1 nonet carrying the quantum number J P C = 1++ [2].
Just as the η − η ′ mixing in the pseudoscalar sector
[2], these two f1 mesons are believed to be a mixture resulting from the
√
¯
mixing between nonstrange f1q ≡ (u¯
u + dd)/
2 and strange f1s ≡ s¯
s states in the popular quark-flavor basis with a single
mixing angle φf1 . And for the mixing angle φf1 , there are several explorations that have been performed from theory and
a
b
c
d
Electronic address:
Electronic address:
Electronic address:
Electronic address:
[email protected]
[email protected]
[email protected]
[email protected]
A Meta-analysis of the 8 TeV ATLAS and CMS
SUSY Searches
Benjamin Nachmana and Tom Rudeliusb
a
arXiv:1410.2270v1 [hep-ph] 8 Oct 2014
SLAC National Accelerator Laboratory, Stanford University
Menlo Park, CA 94025, U.S.A.
b
Jefferson Physical Laboratory, Harvard University
Cambridge, MA 02138, U.S.A.
E-mail: [email protected], [email protected]
Abstract: Between the ATLAS and CMS collaborations at the LHC, hundreds of individual event selections have been measured in the data to look for evidence of supersymmetry
at a center of mass energy of 8 TeV. While there is currently no significant evidence for
any particular model of supersymmetry, the large number of searches should have produced
some large statistical fluctuations. By analyzing the distribution of p-values from the various searches, we determine that the number of excesses is consistent with the Standard
Model only hypothesis. However, we do find a significant shortage of signal regions with
far fewer observed events than expected in both the ATLAS and CMS datasets. While not
as compelling as a surplus of excesses, the lack of deficits could be a hint of new physics
already in the 8 TeV datasets.
SLAC-PUB-16117
UMD-PP-014-016
SU-ITP-14/24
Detecting Boosted Dark Matter from the Sun with Large Volume Neutrino Detectors
Joshua Berger,1 Yanou Cui,2, 3 and Yue Zhao4
1
SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada
3
Maryland Center for Fundamental Physics, University of Maryland, College Park, MD 20742, USA
4
Stanford Institute of Theoretical Physics, Physics Department,
Stanford University, Stanford, CA 94305, USA∗
arXiv:1410.2246v1 [hep-ph] 8 Oct 2014
2
We study novel thermal Dark Matter (DM) scenarios where the annihilation of DM captured in
the Sun produces boosted stable particles in the dark sector. These stable particles can be the
annihilating DM itself, as in the scenario of semi-annihilating DM where DM possesses non-minimal
stabilization symmetries, or can be a lighter subdominant DM component, as in the scenario of
a multi-component DM sector. We investigate both of these possibilities and present concrete
models as proofs of concept, considering DM mass in the wide range of O(1)-O(100) GeV. With
a large Lorentz boost, these boosted DM can be detected in large volume terrestrial experiments,
such as experiments designed for neutrino physics or proton decay searches, via neutral-currentlike interactions with nuclei or electrons. In particular, we propose a search for proton tracks
pointing towards the Sun, which is a primary detection channel for boosted DM from the Sun at
neutrino experiments. We focus on studying the signals at Cherenkov-radiation-based detectors
such as Super-Kamiokande (SK) and its upgrade Hyper-Kamiokande (HK). We find that with spindependent scattering as the dominant DM-nucleus interaction at low energies, boosted DM can
leave detectable signals at SK or HK, while being consistent with current DM direct detection
constraints. The boosted DM signal highlights the distinctive signatures that can arise in nonminimal DM sectors.
Contents
I. Introduction
II. Models
A. Semi-annihilating DM models
1. v 0 operator
2. v 2 operator
B. Two-Component DM models
2
4
5
5
7
8
III. Boosted DM Flux from the Sun
A. DM Capture Rate by the Sun
B. Capture–loss Equilibrium in the Sun
C. Rescattering in the Sun
10
10
11
11
IV. Detection of Boosted DM
A. Detection Mechanism for Signals
B. Background Reduction
12
12
13
V. Results
VI. Conclusion
Acknowledgement
∗ Electronic
address: [email protected], [email protected], [email protected]
14
15
16
Recent Top Properties Measurements at CDF
arXiv:1410.2452v1 [hep-ex] 9 Oct 2014
Giorgio Chiarelli
INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
E-mail: [email protected]
Abstract. We present the most recent CDF results in the measurements of the decay and
production vertex of the top-quark. New results on forward-backward asymmetry in top-antitop
events are presented. Also, recent measurements of the branching fractions of top-quark are
discussed. Finally, measurements in single top events, where top-quark is produced through
electroweak processes, are presented. Despite the much larger number of top events collected at
the LHC, due to the symmetric initial state and the better signal-to-background ratio in specific
channels, some results will be lasting heritage of the Tevatron.
1. Introduction
Top quark was discovered at the Tevatron in 1994-1995. Since then its properties were
extensively studied by the CDF and D0 experiments. The last Tevatron run (2001-2011)
provided almost 10 fb−1 of data to each experiment. In this document I will concentrate on the
most recent CDF results that exploit this wealth of data.
Thanks to its large mass, top is the only quark we can study before hadronization, therefore
we have the unique opportunity to study a ”bare” quark. From an experimental point of view,
observables are (in most cases) perfectly well defined. The importance of this very peculiar
quark cannot be underestimated. Its mass is strictly related, through loops, to the Higgs mass
and to vacuum stability; its large Yukawa coupling is puzzingly close to one.
Top quark can be produced via electroweak mechanism (single top processes) or via strong
interactions (in top-antitop pairs). Despite the very small signal/background ratio for single top
production process, both Tevatron experiments detected (and studied) top quark in both cases.
As top decays in a W and a quark (almost 100% of cases a b-quark), topologies of top-quark
events are classified according to the charged boson decay. For strongly produced top events we
call ”dilepton” events in which both W s decay leptonically, ”l+jets” events in which one of the
two W s decays hadronically and ”all-hadron” the case in which both bosons decay in quarks1 .
Therefore the typical physics objects present in a top-candidate event of interest are one or two
charged leptons (e or µ), from 2 to 4 jets (two coming from b-quark hadronization), and large
missing transverse energy signalling the presence of one or two neutrinos.
In the following analyses we use events with large (> 20 GeV) ET electrons or muons, large
(> 25 GeV) missing transverse energy (MET) and jets of hadrons (reconstructed by a fixed cone
algorithm) with ET > 20 GeV and pseudorapidity |η| < 2.8.
1
In the following I will not present results related to the all-hadronic topology.
October 10, 2014
0:23
WSPC Proceedings - 9.75in x 6.5in
RD˙protvino
1
Rare decays at the LHCb experiment
L. Pescatore∗ , on behalf of the LHCb collaboration
∗ University
of Birmingham, Birmingham, UK
[email protected]
arXiv:1410.2411v1 [hep-ex] 9 Oct 2014
∗ E-mail:
Rare decays of beauty and charm hadrons offer a rich playground to make precise tests
of the Standard Model and look for New Physics at the level of quantum corrections. A
review of recent LHCb results will be presented.
1. Introduction and the LHCb detector
The LHCb experiment 1 is a forward spectrometer fully instrumented in the pseudorapidity range 2 < η < 5. It is characterised by an excellent particle identification,
given by two RICH detectors, and good impact parameter and momenta resolutions
combined with a highly efficient and flexible trigger able to trigger on muons, electrons, hadrons and photons with low pT thresholds. The experiment is very well
suited to study rare decays of b- and c-hadrons as it benefits from large bb and cc
cross-sections and can access very low transverse momentum ranges thanks to its
forward geometry.
The LHCb detector is a precision machine, designed to test in detail the Standard
Model (SM). In these proceedings the analysis of, so-called, “electroweak-penguin”
(EWP) decays will be described. These are Flavour Changing Neutral Currents
(FCNC), forbidden in the SM at tree level, but allowed at loop level. Therefore
they are very sensitive to New Physics (NP) entering the loops and can probe
higher mass scales than direct searches. Furthermore they offer a rich environment
with a wealth of observables sensitive to NP entering in the loops. The result of
two searches for Lepton Flavour Violating (LFV) decays, forbidden in the SM but
with possible tree level contributions beyond it, will also be reported. The analyses
presented in these proceedings are based on a dataset corresponding to up-to 3 fb−1
of integrated luminosity: 1 fb−1 from 2011 run at a collision energy of 7 TeV and
2 fb−1 from 2012 run at 8 TeV.
2. Branching ratios and angular analysis of B → K (∗) µµ decays
The branching fractions (BR) of B → Kµ+ µ− and B → K ∗ µ+ µ− decays are highly
sensitive to NP entering in the loops and LHCb is well suited to study these decays
since it can efficiently trigger on muons. As a first result, the branching fractions of
the B + → K ∗+ µ+ µ− , B + → K + µ+ µ− and B 0 → KS0 µ+ µ− decays are determined
using an integrated luminosity of 3 fb−1 . These are analysed reconstructing K ∗+ →
page 1
October 10, 2014
0:25
WSPC Proceedings - 9.75in x 6.5in
CPV˙protvino
1
CP violation measurements at the LHCb experiment
L. Pescatore∗ , on behalf of the LHCb collaboration
∗ University
of Birmingham, Birmingham, UK
[email protected]
arXiv:1410.2293v1 [hep-ex] 8 Oct 2014
∗ E-mail:
Decays of b-hadrons are the ideal place to perform measurements of CP violation. Many
decay channels allow to over-constrain the unitarity triangles of the CKM matrix and
test the SM hypothesis that a single phase is the origin of all CP violation. Charm
decays also allow for tests of the SM. Recent results from LHCb are reviewed.
1. Introduction
CP violation was first observed by Cronin and Fitch 1 in 1964 in the kaon sector
and is by now well established in the Standard Model (SM). The LHCb experiment
is performing precision measurements in order to consolidate the consistency of the
CKM picture and look for deviations from the CP Violation (CPV) expected in the
SM. A selection of recent results from the LHCb experiment are presented. Where
not explicitly stated all results are based on the analysis of 1 fb−1 of data collected
in 2011 at a proton-proton collision energy of 7 TeV.
2. Measurement of the γ angle
∗
One of the angles of the unitarity triangle is γ = arg [−Vud Vub
/Vcd Vcb∗ ]. At the
moment it has the weakest experimental constrains and therefore its measurement
is an important test of the CKM consistency. LHCb expects to achieve a precision
of 7◦ , after the analysis of the 3 fb−1 collected in 2011 and 2012 has been finished.
The angle is measured using B → Dh decays, where h can be a pion or a kaon. In
these decays γ arises from the interference of b → u and b → c transitions.
The measurement can be carried out using D decays in CP eigenstates KK and
ππ (GLW method 2 ), or also in Kπ (ADS method 3 ). In the latter case the B − →
D0 K − decay is colour favoured but the D0 decay in K + π − is CKM suppressed,
yielding large interference. Combining the two methods and including also D →
KS hh decays the value of γ is measured to be (62 ± 12)◦ 4 . Most of the analysis
included are on 1 fb−1 of data and being updated to 3 fb−1 .
3. Bs mixing and φs measurement
In the neutral B system, mixing is possible thanks to weak interaction box diagrams.
The angle φs arises from the interference of Bs decays with and without mixing.
The value of φs is well known in the SM, φs = −0.0364 ± 0.0016 rad 5 , but New
page 1
October 10, 2014 0:24 WSPC/INSTRUCTION FILE
MPLA-rev-V10
arXiv:1410.2581v1 [gr-qc] 9 Oct 2014
Modern Physics Letters A
c World Scientific Publishing Company
Gravitational Waves and Perspectives for Quantum Gravity
Ilya L. Shapiro
Departamento de F´ısica, ICE, Universidade Federal de Juiz de Fora, MG, Brazil
[email protected]
and
Tomsk State Pedagogical University and Tomsk State University, Tomsk, Russia
Ana M. Pelinson
Departamento de F´ısica, CFM, Universidade Federal de Santa Catarina, SC, Brazil
[email protected]
Filipe de O. Salles
Departamento de F´ısica, ICE, Universidade Federal de Juiz de Fora, MG, Brazil
[email protected]
Received (Day Month Year)
Revised (Day Month Year)
Understanding the role of higher derivatives is probably one of the most relevant questions in quantum gravity theory. Already at the semiclassical level, when gravity is a
classical background for quantum matter fields, the action of gravity should include
fourth derivative terms to provide renormalizability in the vacuum sector. The same situation holds in the quantum theory of metric. At the same time, including the fourth
derivative terms means the presence of massive ghosts, which are gauge-independent
massive states with negative kinetic energy. At both classical and quantum level such
ghosts violate stability and hence the theory becomes inconsistent. Several approaches
to solve this contradiction were invented and we are proposing one more, which looks
simpler than those what were considered before. We explore the dynamics of the gravitational waves on the background of classical solutions and give certain arguments that
massive ghosts produce instability only when they are present as physical particles. At
least on the cosmological background one can observe that if the initial frequency of
the metric perturbations is much smaller than the mass of the ghost, no instabilities are
present.
Keywords: Gravitational waves; Quantum gravity; Higher Derivatives.
PACS Nos.: 04.60.-m, 11.10.Jj, 04.30.Nk, 04.60.Bc,
1. Introduction
General relativity (GR) is a complete theory of classical gravitational phenomena,
which proved valid at the wide range of energies and distances. However, as any
other known physical theory, it has some limits of application. In order to establish
1
Twelve-quark hypernuclei with A = 4 in relativistic quark-gluon model
S.M. Gerasyuta∗ and E.E. Matskevich†
arXiv:1410.2551v1 [nucl-th] 22 Sep 2014
Department of Physics, St. Petersburg State Forest Technical University,
Institutski Per. 5, St. Petersburg 194021, Russia
Hypernuclei 4Y He, 4Y H, 4Y Y He, 4Y Y H, where Y = Λ, Σ0 , Σ+ , Σ− , A = 4 are considered using the
relativistic twelve-quark equations in the framework of the dispersion relation technique. Hypernuclei as the systems of interacting quarks and gluons are considered. The relativistic twelve-quark
amplitudes of hypernuclei, including u, d, s quarks are constructed. The approximate solutions of
these equations are obtained using a method based on the extraction of leading singularities of the
amplitudes. The poles of the multiquark amplitudes allow us to determine the masses of hypernuclei
with the atomic (baryon) number A = B = 4. The mass of state 4Λ He with the isospin projection
I3 = 21 and the spin-parity J P = 0+ is equal to M = 3922 M eV . The mass of 4ΛΛ H M = 4118 M eV
with the isospin projection I3 = 0 and the spin-parity J P = 0+ is calculated. We predict the
mass spectrum of hypernuclei with A = 4, which is valuable to further experimental study of the
hypernuclei.
PACS numbers: 11.55.Fv, 11.80.Jy, 12.39.Ki, 12.39.Mk.
I.
INTRODUCTION.
The hypernuclear physics experimental program, and the difficulties arised in accurately determining rates for
low-energy nuclear reactions, warrant continued effort in the application of LQCD to nuclear physics [1–12].
In the limit of flavor SU (3) symmetry at the physical strange quark mass with quantum chromodynamics (without
electromagnetic interactions) the binding energies of a range of nuclei and hypernuclei with atomic number A ≤ 4
and strangeness |S| ≤ 2, including the deuteron, H-dibaryon, 3 He, 3Λ He, 4 He, 4Λ He and 4ΛΛ He are calculated. From
lattice QCD calculations performed with nf = 3 dynamical light quark using an isotropic discretization, the nuclear
states are extracted [13–15]. It is now clear that the spectrum of nuclei and hypernuclei changes dramatically from
light quark masses.
In our recent paper [16] the relativistic six-quark equations are found in the framework of coupled-channel formalism.
The dynamical mixing between the subamplitudes of hexaquark is considered. The six-quark amplitudes of dibaryons
are calculated. The poles of these amplitudes determine the masses of dibaryons. We calculated the contribution of
six-quark subamplitudes to the hexaquark amplitudes. The model in question has only three parameters: the cutoff
parameter Λ = 11 and gluon coupling constants g0 and g1 . These parameters are determined by the ΛΛ and di-Ω
masses. In our model the correlation of gluon coupling constants g0 and g1 is similar to the S-wave baryon ones [17].
In the previous paper [18], 3 He is considered. The relativistic nine-quark equations are derived in the framework
of the dispersion relation technique. The dynamical mixing between the subamplitudes of 3 He is taken into account.
The relativistic nine-quark amplitudes of 3 He, including the u, d quarks are calculated. The approximate solutions
of these equations were obtained using a method based on the extraction of leading singularities of the amplitudes.
The pole of the nonaquark amplitudes determined the mass of 3 He.
The experimental mass value of 3 He is equal to M = 2808.39 M eV . The experimental data of the hypertriton
mass is M = 2991.17 M eV . This model use only three parameters, which are determined by the following masses:
the cutoff Λ = 9.0 and the gluon coupling constant g = 0.2122. The mass of the u-quark is m = 410 M eV , and the
mass of strange quark ms = 607 M eV , which takes into account the confinement potential (the shift mass is equal to
50 M eV ) [19].
The relativistic nona-amplitudes of low-lying hypernuclei, including the three flavors (u, d, s) are calculated. The
degeneracy of the isospin 0, 1, 2 is predicted in the lowest hypernuclei. It is the property of our approach. The
+
+
low-lying hypernuclei with the spin-parity J P = 12 , 23 are calculated. We calculated the masses and the binding
energies of 12 hypernuclei with A = 3. The binding energy is small for the states 3Λ He, 3Λ H, and nnΛ. In the other
cases, the binding energies are large, ∼ 50 – 100 M eV . We have calculated only five systems of equations; therefore,
the masses of hypernuclei are degenerated. We do not include the electromagnetic effect contribution.
∗ Electronic
† Electronic
address: [email protected]
address: [email protected]
Static quark-antiquark potential in the quark-gluon plasma from lattice QCD
Yannis Burnier,1 Olaf Kaczmarek,2 and Alexander Rothkopf3
1
Institute of Theoretical Physics, EPFL, CH-1015 Lausanne, Switzerland
Fakult¨
at f¨
ur Physik, Universit¨
at Bielefeld, D-33615 Bielefeld, Germany
3
Institute of Theoretical Physics, Universit¨
at Heidelberg, Philosophenweg 12, D-69120 Germany
(Dated: October 10, 2014)
2
arXiv:1410.2546v1 [hep-lat] 9 Oct 2014
We present a state-of-the-art determination of the complex valued static quark-antiquark potential
at phenomenologically relevant temperatures around the deconfinement phase transition. Its values
are obtained from non-perturbative lattice QCD simulations using spectral functions extracted via
a novel Bayesian inference prescription. We find that the real part, both in a gluonic medium as
well as in realistic QCD with light u, d and s quarks, lies close to the color singlet free energies
in Coulomb gauge and shows Debye screening above the (pseudo) critical temperature Tc . The
imaginary part is estimated in the gluonic medium, where we find that it is of the same order of
magnitude as in hard-thermal loop resummed perturbation theory in the deconfined phase.
The potential acting between a heavy quark and antiquark in a thermal medium is a central ingredient in our
understanding of the strong interactions, described by
quantum chromo-dynamics (QCD). The bound states it
sustains, heavy quarkonium, are precision probes connecting theory and experiment [1]. They allow us to
test QCD via low temperature spectroscopy [2], as well
as through their in-medium modification [3–5] observed
in the quark gluon plasma created in relativistic heavy
ion collisions. In particular the open question of melting
and regeneration observed at RHIC and LHC [6] urges a
quantitative understanding of their in-medium behavior.
A wealth of intuition has been accumulated in the past
based, in part, on analogies with Abelian theories [3], potential modeling [7] and strong coupling approaches [8].
Lattice QCD at T = 0 tells us [9] that the potential rises
linearly before flattening off due to string breaking. Perturbation theory on the other hand shows that Debye
screening plays a major role in the deconfined phase. At
T & Tc , reached in current experiments, we expect that
the medium gradually weakens the interaction. How the
transition between the two regimes manifests itself quantitatively in the potential however remained unanswered.
Due to recent conceptual and methods developments we
are now able to present in this letter a first principles determination of the temperature dependence of the static
inter-quark potential in the phenomenologically relevant,
i.e. non-perturbative regime around the phase transition.
The advent [10] of modern effective field theory allowed
to put the definition of the static potential on a rigorous
mathematical footing. By exploiting the separation between the heavy quark rest mass and medium scales, a
derivation from a dynamical QCD observable, the realtime thermal Wilson loop W (t, r) was achieved,
i∂t W (t, r)
.
t→∞ W (t, r)
V (r) = lim
(1)
This expression has been evaluated at finite temperature
in hard thermal loop (HTL) resummed perturbation theory [11] and was found to be complex valued. In the de-
confined phase the real part shows Debye screening, while
the imaginary part is related to the scattering (Landau
damping) and absorption (singlet-octet transition) of gluons from the medium. Even though at leading order the
real part coincides with the color singlet free energies
in Coulomb gauge, this agreement is already not exact
at next-to-leading order [12]. Calculating the potential
to higher order in perturbation theory is a difficult task
[13] and given the size of the strong coupling and the
infrared problems in gauge theories, it is evident that
non-perturbative methods within QCD, such as lattice
simulations are required. The main difficulty we face is
that numerical calculations are performed in imaginary
time without direct access to dynamical quantities, such
as W (t, r).
In Ref. [14] a strategy was laid out how to evaluate the
real-time definition Eq. (1) using Euclidean lattice QCD
simulations. It is based on a spectral decomposition
Z
Z
−ωτ
W (τ ) = dωe
ρ(ω) ↔
dωe−iωt ρ(ω) = W (t),
where W (τ ) denotes the Euclidean time Wilson loop accessible on the lattice. The above can be combined with
Eq.(1) to yield
Z
Z
V (r) = lim
dω ωe−iωt ρ(ω, r)/ dω e−iωt ρ(ω, r), (2)
t→∞
in turn relating the values of the potential to the spectral
function ρ(ω, r), which can in principle be obtained from
lattice QCD.
The first practical challenge lies in obtaining the function ρ(ω, r) in Eq. (2) from a finite lattice QCD dataset
W (τn , r), n = 1..Nτ with statistical errors. Extracting
from it continuous spectral features is an inherently illposed problem, which however can be given meaning by
the use of Bayesian inference. In this well established statistical approach, additional prior information is used to
select a unique solution from an otherwise undetermined
χ2 fit. Unfortunately the standard methods, such as the
Maximum Entropy Method (MEM) or extended MEM
Torsional oscillations of neutron stars in scalar-tensor theory of gravity
Hector O. Silva,1, ∗ Hajime Sotani,2, † Emanuele Berti,1, ‡ and Michael Horbatsch1, 3, §
arXiv:1410.2511v1 [gr-qc] 9 Oct 2014
1
Department of Physics and Astronomy, The University of Mississippi, University, MS 38677, USA
2
Division of Theoretical Astronomy, National Astronomical
Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
3
School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
(Dated: October 10, 2014)
We study torsional oscillations of neutron stars in the scalar-tensor theory of gravity using the
relativistic Cowling approximation. We compute unperturbed neutron star models adopting realistic equations of state for the neutron star’s core and crust. For scalar-tensor theories that allow for
spontaneous scalarization, the crust thickness can be significantly smaller than in general relativity.
We derive the perturbation equation describing torsional oscillations in scalar-tensor theory, and
we solve the corresponding eigenvalue problem to find the oscillation frequencies. The fundamental
mode (overtone) frequencies become smaller (larger) than in general relativity for scalarized stellar
models. Torsional oscillation frequencies may yield information on the crust microphysics if microphysics effects are not degenerate with strong-gravity effects, such as those due to scalarization. To
address this issue, we consider two different models for the equation of state of the crust and we look
at the effects of electron screening. The effect of scalarization on torsional oscillation frequencies
turns out to be smaller than uncertainties in the microphysics for all spontaneous scalarization models allowed by binary pulsar observations. Our study shows that the observation of quasi-periodic
oscillations (QPOs) following giant flares can be used to constrain the microphysics of neutron star
crusts, whether spontaneous scalarization occurs or not.
PACS numbers: 04.40.Dg, 97.60.Jd, 04.50.Kd, 04.80.Cc
I.
INTRODUCTION
Observations of quasi-periodic oscillations (QPOs) following giant flares in soft gamma-ray repeaters [1–3] suggest a close coupling between the seismic motion of the
crust after a major quake and the modes of oscillations in
a magnetar. The analysis of X-ray data in SGR 1900+14
[2] and SGR 1806-20 [3] has unveiled a number of periodicities, with frequencies that agree reasonably well
with the expected torsional (or toroidal shear) oscillation modes of the neutron star (NS) crust: see e.g. [4]
for a review, and [5] for recent progress in explaining
apparent discrepancies between theoretical models and
observations. These observations are very exciting because they allow us, for the very first time, to test NS
oscillation models.
The foundations of crustal torsional oscillation theory
in general relativity (GR) were laid in a classic paper by
Schumaker and Thorne [6]. Recent work motivated by
QPO observations explored how torsional oscillation frequencies are affected by various physical effects, including
crustal elasticity [7], magnetic fields [8–10], superfluidity
[11], the nuclear symmetry energy [12–14] and electron
screening [15].
The main motivation of this paper is to answer the
following question: could torsional oscillation frequencies carry observable imprints of strong-field dynamics,
∗
†
‡
§
[email protected]
[email protected]
[email protected]
[email protected]
and possibly hint at dynamics beyond GR? Vice versa,
can we ignore effects due to hypothetical strong-field
modifications of GR when we explore the dependence of
torsional oscillation frequencies on the various physical
mechanisms listed above?
We address these questions within the simplest class
of modifications of GR, namely scalar-tensor theory.
Damour and Esposito-Far`ese [16] showed that a wide
class of scalar-tensor theories can pass Solar System tests
and exhibit nonperturbative strong-field deviations away
from GR (“spontaneous scalarization”) that can potentially be measured by observations of the bulk properties
of NSs, and of binary systems containing NSs. The magnitude of these deviations is very sensitive to the value of
a certain theory parameter β, defined in Eq. (16) below1 .
Static NSs in theories with spontaneous scalarization
were first studied in [16]. Their stability was investigated using catastrophe theory by Harada [17, 18]. The
formation of scalarized NSs in gravitational collapse was
studied in [19, 20], and a possible mechanism to “seed”
macroscopic scalar fields from quantum vacuum instabilities was recently suggested [21–23]. Slowly rotating NSs
were studied at first [24, 25] and second [26] order in rotation by extending the Hartle-Thorne formalism [27, 28].
Recent work [29–31] addressed the properties of rapidly
rotating NS models.
Widely-separated binary systems of compact objects
in scalar-tensor theory have been studied in [24, 32, 33],
1
There exists a threshold βc ∼ −4.5, whose exact value depends
on the NS equation of state. Scalarization is possible when β <
βc .
IFUP-TH-2014-10
arXiv:1410.2443v1 [hep-th] 9 Oct 2014
Holographic QCD with Dynamical
Flavors
Francesco Bigazzia and Aldo L. Cotroneb
a
b
INFN, Sezione di Pisa; Largo B. Pontecorvo 3, I-56127 Pisa, Italy.
Dipartimento di Fisica e Astronomia, Universit`a di Firenze and INFN, Sezione di
Firenze; Via G. Sansone 1, I-50019 Sesto Fiorentino (Firenze), Italy.
[email protected], [email protected]
Abstract
Gravity solutions describing the Witten-Sakai-Sugimoto model of holographic QCD with
dynamical flavors are presented. The field theory is studied in the Veneziano limit, at first
order in the ratio of the number of flavors and colors. The gravity solutions are analytic and
dual to the field theory either in the confined, low temperature phase or in the deconfined,
high temperature phase with small baryonic charge density. The phase diagram and the flavor contributions to vacuum (e.g. string tension and hadron masses) and thermodynamical
properties of the dual field theory are then deduced. The phase diagram of the model at
finite temperature and imaginary chemical potential, as well as that of the unflavored theory
at finite θ angle are also discussed in turn, showing qualitative similarities with recent lattice
studies. Interesting degrees of freedom in each phase are discussed.
Covariant counterterms for the Witten-Sakai-Sugimoto model are provided both in the probe
approximation and in the backreacted case, allowing for a standard holographic renormalization of the theory.
1
UAB-FT-763, MPP-2014-369
Non extensive thermodynamics and neutron star properties
D´ebora P. Menezes,1 Airton Deppman,2 Eugenio Meg´ıas,3, 4 and Luis B. Castro5
arXiv:1410.2264v1 [nucl-th] 8 Oct 2014
1 Departamento
de F´ısica - CFM - Universidade Federal de Santa Catarina,
Florian´
opolis - SC - CP. 476 - CEP 88.040 - 900 - Brazil
email: [email protected]
2 Instituto de F´
ısica, Universidade de S˜
ao Paulo - Rua do Mat˜
ao Travessa
R Nr.187 CEP 05508-090 Cidade Universit´
aria, S˜
ao Paulo - Brasil
email: [email protected]
3 Grup de F´
ısica Te`
orica and IFAE, Departament de F´ısica,
Universitat Aut`
onoma de Barcelona, Bellaterra E-08193 Barcelona, Spain
4 Max-Planck-Institut f¨
ur Physik (Werner-Heisenberg-Institut),
F¨
ohringer Ring 6, D-80805, Munich, Germany
email: [email protected]
5 Departamento de F´
ısica, Universidade Federal do Maranh˜
ao,
Campus Universit´
ario do Bacanga, CEP 65080-805, S˜
ao Lu´ıs, MA, Brazil
email: [email protected]
In the present work we apply non extensive statistics to obtain equations of state
suitable to describe stellar matter and verify its effects on microscopic and macroscopic quantities. Two snapshots of the star evolution are considered and the direct
Urca process is investigated with two different parameter sets. q-values are chosen
as 1.05 and 1.14. The equations of state are only slightly modified, but the effects
are enough to produce stars with slightly higher maximum masses. The onsets of
the constituents are more strongly affected and the internal stellar temperature decreases with the increase of the q-value, with consequences on the strangeness and
cooling rates of the stars.
PACS numbers: 05.70.Ce, 21.65.-f, 26.60.-c, 95.30.Tg
I.
INTRODUCTION
A type II supernova explosion is triggered when massive stars (8 M⊙ < M < 30 M⊙ )
exhaust their fuel supply, causing the core to be crushed by gravity. The remnant of this
gravitational collapse is a compact star or a black hole, depending on the initial condition
of the collapse. Newly-born protoneutron stars (PNS) are hot and rich in leptons, mostly
e− and νe and have masses of the order of 1 − 2 M⊙ [1, 2]. During the very beginning
of the evolution, most of the binding energy, of the order of 1053 ergs is radiated away by
the neutrinos. During the temporal evolution of the PNS in the so-called Kelvin-Helmholtz
epoch, the remnant compact object changes from a hot and lepton-rich PNS to a cold and
deleptonized neutron star [3]. The neutrinos already present or generated in the PNS hot
matter escape by diffusion because of the very high densities and temperatures involved.
At zero temperature no trapped neutrinos are left in the star because their mean free path
would be larger than the compact star radius. Simulations have shown that the evolutionary
picture can be understood if one studies three snapshots of the time evolution of a compact
star in its first minutes of life [4]. At first, the PNS is warm (represented by fixed entropy per
particle) and has a large number of trapped neutrinos (represented by fixed lepton fraction).
Prepared for submission to JHEP
arXiv:1410.2257v1 [hep-th] 8 Oct 2014
SU-ITP-14/23, MIT-CTP/4598
Explicitly Broken Supersymmetry with
Exactly Massless Moduli
Xi Dong,a Daniel Z. Freedmana,b and Yue Zhaoa
a Stanford
Institute for Theoretical Physics, Department of Physics, Stanford University,
Stanford, CA 94305, U.S.A.
b Center
for Theoretical Physics and Department of Mathematics, Massachusetts Institute of
Technology, Cambridge, MA 02139, U.S.A.
E-mail:
[email protected], [email protected], [email protected]
Abstract: There is an avatar of the little hierarchy problem of the MSSM in 3dimensional supersymmetry. We propose a solution to this problem in AdS3 based on
the AdS/CFT correspondence. The bulk theory is a supergravity theory in which U(1)
× U(1) R-symmetry is gauged by Chern-Simons fields. The bulk theory is deformed by
a boundary term quadratic in the gauge fields. It breaks SUSY completely and sources
an exactly marginal operator in the dual CFT. SUSY breaking is communicated by
gauge interactions to bulk scalar fields and their spinor superpartners. Since the Rcharges of scalar and spinor differ, this generates a SUSY breaking shift of their masses.
The Ward identity facilitates the calculation of these mass shifts to any desired order
in the strength of the deformation. Moduli fields are massless R-neutral bulk scalars
with vanishing potential in the undeformed theory. These properties are maintained to
all orders in the deformation despite the fact that moduli couple in the bulk to loops
of R-charged fields.
Perspective on completing natural inflation
Ki-Young Choi,1 Jihn E. Kim,2 and Bumseok Kyae3
2
1
Korea Astronomy and Space Science Institute, Daejeon 305-348, Republic of Korea,
Department of Physics, Seoul National University, Seoul 151-747, Republic of Korea, and
Department of Physics, Kyung Hee University, Seoul 130-701, Republic of Korea,
3
Department of Physics, Pusan National University, Busan 609-735, Republic of Korea
arXiv:1410.1762v1 [hep-th] 7 Oct 2014
We present a perspective on the inflation paths in 2−, 3−, · · · , N −flation models. The number
of non-Abelian gauge groups for a natural inflation is restricted in string compactification, and
we argue that the most plausible completion of natural inflation from a theory perspective is the
2–flation.
PACS numbers:
Keywords: Natural inflation, 2-flation, N-flation, High scale inflation, GUT scale groups
I.
INTRODUCTION
Completing natural inflation has attracted a great deal
of attention [1] after the BICEP2 result [2]. The idea was
presented some time ago [3].
Cosmic inflation is an attractive paradigm for a solution of the homogeneity and flatness problems [4–
6]. For a sufficient inflation with the e-fold number
e > 70,1 one needs small slow-roll inflation-parameters,
ǫ (≡ 21 MP2 (V ′ /V )2 ) and η (≡ MP2 V ′′ /V ) [8, 9]. Single bubble inflation was proposed with the initial condition near the origin in the Coleman-Weinberg type
logarithmically-flat hilltop potential [10], or at a large
field value for a chaotic type potential [11]. With the
slow-roll conditions satisfied, the local non-Gaussianities
local
|fNL
| are much smaller than 1 for a single field inflation
[12], which was observed by the Planck 2013 data [13].
In addition, the hybrid inflation predicting ns > 1 (arising from the hilltop inflation) [14] and the λφ4 chaotic
inflation are disfavored from the data [13].
The negligible non-Gaussianity pin down the inflation
models to the single field m2 φ2 chaotic inflation [1] or the
multi-field hilltop inflation [14]. The m2 φ2 chaotic inflation needs a fine-tuning of order m2 ≈ 10−10 in units of
the reduced Planck mass, MP ≃ 2.44 × 1018 GeV. For
the predictability of the Einstein equation, we need that
the potential V during inflation must be much smaller
than MP4 . In fact, this can be easily realized in natural
inflation where there exists a GUT scale heavy axion coupling to a GUT scale confining force [15]. With the heavy
axion potential at the GUT scale (≈ ΛGUT ≈MGUT ),
the explicit breaking potential of the Peccei-Quinn (PQ)
symmetry is given by ∝ 21 Λ4GUT (1 − cos(a/f )); thus the
potential energy is bounded by Λ4GUT .
The m2 φ2 chaotic inflation has a problem, “Why does
1
The number of e-foldings required in inflation depends on the
specific models as well as the dynamics after inflation. Even
though the number relevant for the observed CMB anisotropies
is typically around 50–60, here we use the minimum value 70
given in Ref. [7] sufficient for most of inflationary models.
one keep only the quadratic term?” It is known that a
large trans-Planckian field value is needed in the m2 φ2
chaotic inflation for a large tensor-to-scalar ratio r, which
is known as the Lyth bound hφi > 15 MP [16]. In particular, with the large trans-Planckian field value higher
order terms might be more important [14]. To reconcile
the trans-Planckian field value with the natural inflation
idea, Kim, Nilles, and Peloso (KNP) introduced two axions and two confining forces at the GUT scale. It has
been generalized to N-flation [17].
An ultra-violet completed theory, in particular the heterotic string theory, may not allow a large number of nonAbelian gauge groups. We scrutinize the inflaton path,
arising from the limited rank of the total gauge group,
and present an argument that 2-flation, i.e. the KNP
type, is an easily realizable one.
In Sec. II, we briefly review the KNP scenario and its
N-flation extension. In Sec. III, we discuss the maximum
rank of the heterotic string, which is argued for a limitation of the number of GUT scale confining gauge groups.
Sec. IV is a conclusion.
II.
THE 2-FLATION
A large vacuum expectation value (VEV) of a scalar
field is possible with a small mass parameter if a very
small coupling constant λ is assumed,
V =
1
λ(|φ|2 − f 2 )2 .
4
(1)
The mass parameter in this theory is m2 = λf 2 . With a
GUT scale m, f can be trans-Planckian of order > 10MP
for λ < 10−6 . However, the potential (1) with the small
λ describes inflation starting from near the convex hilltop
point (due to the high temperature effect before inflation)
and hence it is not favored by the BICEP2 data [14].
This has led to the recent surge of studies on concave
potentials near the origin of the field space in case of
single field inflations [1]. The concave potentials give
positive η’s.
The simplest concave potential is the m2 φ2 chaotic potential. Since this potential is not bounded from above,
Dante’s Waterfall
Christopher D. Carone,∗ Joshua Erlich,† Anuraag Sensharma,‡ and Zhen Wang§
arXiv:1410.2593v1 [hep-ph] 9 Oct 2014
High Energy Theory Group, Department of Physics,
College of William and Mary, Williamsburg, VA 23187-8795
(Dated: October 10, 2014)
Abstract
We describe a hybrid axion-monodromy inflation model motivated by the Dante’s Inferno scenario. In Dante’s Inferno, a two-field potential features a stable trench along which a linear
combination of the two fields slowly rolls, rendering the dynamics essentially identical to that of
single-field chaotic inflation. A shift symmetry allows for the Lyth bound to be effectively evaded
as in other axion-monodromy models. In our proposal, the potential is concave downward near the
origin and the inflaton trajectory is a gradual downward spiral, ending at a point where the trench
becomes unstable. There, the fields begin falling rapidly towards the minimum of the potential
and inflation terminates as in a hybrid model. We find parameter choices that reproduce observed
features of the cosmic microwave background, and discuss our model in light of recent results from
the BICEP2 and Planck experiments.
∗
[email protected]
†
[email protected]
[email protected]
‡
§
[email protected]
1
arXiv:1410.2493v1 [hep-ph] 9 Oct 2014
EPJ Web of Conferences will be set by the publisher
DOI: will be set by the publisher
c Owned by the authors, published by EDP Sciences, 2014
Hybrid exotic mesons in soft-wall AdS/QCD
Loredana Bellantuono1,2 , a
1
2
INFN-Sezione di Bari, via Orabona 4, 70126 Bari, Italy
Dipartimento di Fisica, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70126 Bari, Italy
Abstract. Hybrid mesons with exotic quantum numbers J PC = 1−+ are examined in softwall AdS/QCD. The predicted mass spectrum is compared to the measured values of the
candidates π1 (1400), π1 (1600) and π1 (2015). Thermal effects are analysed through the
spectral function in the AdS-Black Hole model, and the differences with the HawkingPage description are discussed.
1 Introduction
Quantum Chromodynamics (QCD) describes strong interactions among quarks as processes in which
colored gluons are exchanged. By virtue of their own color charge, gluons also strongly interact with
quarks and among themselves. For
reason, a meson should be considered as a linear superposi this
tion of color-singlet bound states qq0 , qqq0 q0 , qGq0 , |GGi , . . . , comprising quarks (q), antiquarks
(q) and gluons (G) as constituents [1]. These states can be classified, respectively, as quark model
"quarkonia", "multiquarks", "hybrids", "glueballs", and so forth. These structures determine angular
momentum, parity and charge-conjugation quantum numbers J PC of the meson, and they yield also
exotic combinations not included in the quark model qq0 picture.
Hybrid configuration, composed by a quark-antiquark pair plus a constituent gluon, accounts for
either ordinary or exotic J PC quantum numbers. Therefore, experimental evidence of these states can
come from overpopulations of the ordinary J PC spectra compared to quark model prediction, or from
the detection of exotic states. The first strategy seems unfruitful, because of the densely populated
spectrum of light mesons in the mass region between 1 and 2 GeV, and the broad nature of the states
involved [2]. On the other hand, states that can have exotic quantum numbers are multiquarks and
hybrids. They have been searched in experiments aiming at the detection of their decay products,
but the analysis has revealed cumbersome. The identification of exotic resonances would be a strong
argument supporting the existence of hybrid bound states. Several QCD models identify the meson
with J PC = 1−+ as the lowest-lying exotic state, with mass predictions varying between 1.5 and 2.2
GeV [2]. Currently, in the light quark sector there are three candidates for hybrid 1−+ states: π1 (1400),
π1 (1600) and π1 (2015). Their measured masses are M(π1 (1400)) = 1354 ± 25 MeV, M(π1 (1600)) =
1662+8
−9 MeV and M(π1 (2015)) = 2014 ± 20 ± 16, 2001 ± 30 ± 92 MeV [3]. Further information on
the detection of such states can be found in the bibliography of [4]. The nature of 1−+ candidates is
still a debated issue, and new experiments with higher statistics and better acceptance are expected to
improve present understandings [2].
a e-mail: [email protected]
Viable textures for the fermion sector
A. E. C´arcamo Hern´andez∗
Universidad T´ecnica Federico Santa Mar´ıa and Centro Cient´ıfico-Tecnol´
ogico de Valpara´ıso
Casilla 110-V, Valpara´ıso, Chile
arXiv:1410.2481v1 [hep-ph] 9 Oct 2014
I. de Medeiros Varzielas†
Department of Physics, University of Basel,
Klingelbergstr. 82, CH-4056 Basel, Switzerland and
School of Physics and Astronomy,
University of Southampton,
Southampton, SO17 1BJ, U.K.
(Dated: October 10, 2014)
We consider a modification of the Fukuyama-Nishiura texture and compare it to the precision
quark flavour data, finding that it fits the data very well. We then propose different viable textures
for quarks, where only the Cabibbo mixing arises from the down sector, and extend to the charged
leptons while constructing a complementary neutrino structure that leads to viable lepton masses
and mixing.
I.
INTRODUCTION
The flavour puzzle is not understood in the context of
the Standard Model (SM), which does not specify the
Yukawa structures and has no justification for the number of generations. As such, extensions addressing the
fermion masses and mixing are particularly appealing.
In building models that address the flavour problem, it is
important to know structures that lead to the observed
fermion flavour data, and in this work we introduce two
proposals.
We start by revisiting the Fukuyama-Nishiura (FN) texture [1, 2], which is no longer phenomenologically viable
as shown in [3]. A simple modification is to modify the
texture slightly by enabling a non-zero 11 entry, which
we show is already a viable texture.
We then introduce other quark textures where the
Cabibbo angle comes from the down quarks whereas the
other mixing angles come from the up sector, which also
successfully describes the quark masses and mixing. We
extend this to the lepton sector, with charged leptons
sharing the texture of the down quarks and the neutrinos significantly contributing to a viable PMNS mixing
matrix.
Other works in the literature considering textures include
[4, 5], and some recent works such as [6–8].
II.
A.
TEXTURES FOR THE QUARK SECTOR
Fukuyama-Nishiura texture and its modification
Proposed for leptons in [1] and also used for quarks in
[2], the FN texture consists in mass matrices of the form:

0 Af Af
 Af Bf Cf  .
Af Cf Bf

(1)
In [3] it was shown that this texture doesn’t quite work
currently, because it fails to reproduce the observed value
of the CP violating phase δ. A simple modification of the
texture is to consider


Df Af Af
ff =  Af Bf Cf  .
M
Af Cf Bf
(2)
with the complex phases included in the following way:
Mf =
ff P † ,
Pf M
f

1
0
0
0 ,
Pf =  0 e−iβ f
0
0
e−iγ f

(3)
ff is
where Af , Bf , Cf and Df are real parameters. M
diagonalized by an orthogonal matrix Rf :
∗
†
[email protected]
[email protected]
ff Rf = diag (−mf1 , mf2 , mf3 ) ,
RfT M
(4)
Noname manuscript No.
(will be inserted by the editor)
Pedro Jimenez-Delgado
arXiv:1410.2431v1 [hep-ph] 9 Oct 2014
Delineating the polarized and unpolarized partonic
structure of the nucleon
Received: date / Accepted: date
Abstract Reports on our latest extractions of parton distribution functions of the nucleon are given. First an
overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong
coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second
part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are
reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact
of present and future data in our understanding of the spin of the nucleon.
Keywords perturbative quantum chromodynamics · parton distribution functions · polarized scattering
1 Introduction
Perturbative quantum chromodynamics has been shown to provide an excellent description of hard scattering
processes at particle accelerators. The quantitative description of high-energy collisions involving hadrons in
the initial state relies on the fact that in such interactions the hadronic structure, in terms of their constituent
quarks and gluons (partons), may be embodied by universal parton distribution functions (PDFs). In a first
approximation the PDFs can be taken (at a resolution scale) to depend only on the momentum (fraction) of
the parton parallel to that of the hadron to which it belongs (parent). Thus additional degrees of freedom,
namely the transverse components of the parton momentum as well as spatial dependences, are disregarded
(integrated out). This defines the so-called collinear approximation, which has been developed over the last
few decades by the world community and provides the base for many analyses at current facilities.
The PDFs are typically determined by simultaneously fitting a wide variety of data for large momentum
transfer processes (global analysis). The parameters of the fits describe the PDFs at some initial (input) scale,
while evolution equations are then used to calculate the PDFs at all other scales needed for the calculations.
Although in principle the fundamental distributions in nature are the PDFs for a specific helicity ( fi↑ and fi↓ ,
i.e. corresponding respectively to parton spins aligned and anti-aligned with that of the hadron), experiments
with unpolarized beams and targets are sensitive only to the averaged helicity distributions or unpolarized
PDFs ( fi = fi↑ + fi↓ ), while information on the polarized distributions (∆ fi = fi↑ − fi↓ ) can be obtained from
measurements involving polarized beams and/or targets. Thus traditionally the unpolarized and polarized
cases have been treated separately, although in principle one could perform a global fit of polarized and
unpolarized data simultaneously.
A comprehensive review on the determination of polarized and unpolarized PDFs has been recently presented in [1], in this talk we will briefly discuss some aspects of our latest extractions. We will start with
Pedro Jimenez-Delgado
Thomas Jefferson National Accelerator Facility
12000 Jefferson Avenue, Suite 1, Newport News, VA 23606, USA
Tel.: +1-757-269-7870
Fax: + 1-757-269-7002
E-mail: [email protected]
arXiv:1410.2428v1 [hep-ph] 9 Oct 2014
The Journal’s name will be set by the publisher
DOI: will be set by the publisher
c Owned by the authors, published by EDP Sciences, 2014
IFJPAN-IV-2014-14
Analysis of BaBar data for three meson tau decay modes using
the Tauola generator
Olga Shekhovtsova1,2 , a
1
2
Institute of Nuclear Physics PAN ul. Radzikowskiego 152 31-342 Krakow, Poland
Kharkov Institute of Physics and Technology 61108, Akademicheskaya,1, Kharkov, Ukraine
Abstract. The hadronic current for the τ− → π− π+ π− ντ decay calculated in the framework
of the Resonance Chiral Theory with an additional modification to include the σ meson
is described. Implementation into the Monte Carlo generator Tauola and fitting strategy to get the model parameters using the one-dimensional distributions are discussed.
The results of the fit to one-dimensional mass invariant spectrum of the BaBar data are
presented. This paper is based on [1].
1 Introduction
The precise experimental data for tau lepton decays collected at B-factories (both Belle and BaBar)
provide an opportunity to measure the Standard Model (SM) parameters, such as the strong coupling
constant, the quark-mixing matrix, the strange quark mass etc, and for searching new physics, beyond
SM. The leptonic decay modes of the tau lepton allow to test the universality of the lepton couplings to
the gauge bosons. The hadronic decays (in fact, the tau lepton due to its high mass is only one that can
decay into hadrons) give an information about the hadronization mechanism and resonance dynamics
in the energy region where the methods of the perturbative QCD cannot be applied. Also hadronic
flavour-violating and CP violating decays of tau lepton allow to search for new physics scenario.
Hadronic tau lepton decays are also a tool in high-energy physics. At the LHC and future linear
colliders a correct simulation of the hadronic decay modes, mainly two pion and three pion modes, is
needed to measure the Higgs spin and its CP properties.
The implementation of the appropriate information on the hadronization of the QCD currents
represents a key task of the TAUOLA library [2, 3]. TAUOLA is a Monte Carlo generator (MC)
dedicated to generating tau decays and it is used in the analysis of experimental data both at Bfactories and LHC. It is important to include in the analyses the information of QCD itself and not of
ad-hoc models that may screen the appropriate information from data. On the other hand an agreement
with experimental data is essential and verifies a theoretical model. Resonance Chiral Theory (RChT)
[4, 5] provides such a reliable framework as it has been shown in many previous publications [6–
9]. A set of RChT currents for the main two meson and three meson, namely, π− π0 , K − π0 , K 0 π− ,
π− π− π+ , π0 π0 π− , K − π− K + , K 0 π− K¯ 0 and K − π0 K 0 , was installed. That set covers more than 88% of
total hadronic τ width. The implementation of the currents, technical tests on it as well as necessary
theoretical concepts are documented in [10].
a e-mail: [email protected]
arXiv:1410.2425v1 [hep-ph] 9 Oct 2014
International Journal of Modern Physics: Conference Series
c The Authors
Generalized Loop Space and Evolution of the Light-Like Wilson Loops
Igor O. Cherednikov
EDF, Departement Fysica, Universiteit Antwerpen, Antwerp, B-2020 Belgium
[email protected]
Tom Mertens
EDF, Departement Fysica, Universiteit Antwerpen, Antwerp, B-2020 Belgium
[email protected]
Equations of motion for the light-like QCD Wilson loops are studied in the generalized
loop space (GLS) setting. To this end, the classically conformal-invariant non-local variations of the cusped Wilson exponentials lying (partially) on the light-cone are formulated
in terms of the Fr´
echet derivative. The rapidity and renormalization-group behaviour of
the gauge-invariant quantum correlation functions (in particular, the three-dimensional
parton densities) are demonstrated to be connected to certain geometrical properties of
the Wilson loops defined in the GLS.
Keywords: Wilson lines and loops; generalised loop space; QCD factorization.
PACS numbers:13.60.Hb,13.85.Hd,13.87.Fh,13.88.+e
1. Introduction
The QCD factorization approach to the analysis of the semi-inclusive high-energy
processes entails the introduction of transverse-momentum dependent parton densities (TMD), which generalise the collinear (integrated) PDFs and contain essential
information about three-dimensional intrinsic structure of the nucleon [1]. In Ref.
[2] the following factorization scheme (valid in the large Bjorken-x regime) for a
generic transverse-distance dependent quark distribution function
Z
(1)
F (x, b⊥ ) = d2 k⊥ e−ib⊥ k⊥ F (x, k⊥ )
has been proposed
F x, b⊥ ; η, µ2 ≈ H(µ2 , P 2 ) · Φ(x, b⊥ ; η, µ2 ),
(2)
where the x-independent jet function H describes the incoming (collinear) partons
and the soft function Φ can be defined as the Fourier transform of an element of
This is an Open Access article published by World Scientific Publishing Company. It is distributed
under the terms of the Creative Commons Attribution 3.0 (CC-BY) License. Further distribution
of this work is permitted, provided the original work is properly cited.
1
Heavy quarkonium properties from Cornell potential using variational method and
supersymmetric quantum mechanic
Alfredo Vega1,2 and Jorge Flores1
1
Instituto de F´ısica y Astronom´ıa,
Universidad de Valpara´ıso,
Avenida Gran Breta˜
na 1111, Valpara´ıso, Chile
2
arXiv:1410.2417v1 [hep-ph] 9 Oct 2014
Centro de Astrof´ısica de Valpara´ıso,
Universidad de Valpara´ıso,
Avenida Gran Breta˜
na 1111, Valpara´ıso, Chile
(Dated: October 10, 2014)
Using the variational method and supersymmetric quantum mechanic we calculate in a approximate way eigenvalues, eigenfunctions and wave functions at origin of Cornell potential. We compare
results with numerical solutions for heavy quarkonia c¯
c, b¯b y b¯
c.
PACS numbers: 14.40.Pq, 12.39.Pn, 12.60.Jv, 03.65.Ge
Keywords: Quarkonium, Variational Method, Supersymmetric Quantum Mechanic
I.
INTRODUCTION
Since the discovery of J/ψ in 1974 [1, 2] the study
of heavy quarkonium has been very valuable in hadron
physics, because they involve non perturbative aspect
of QCD and there are many experimental data involving those hadrons [3–5]. From a theoretical standpoint,
heavy quarkonium has been studied from several approaches [6, 7], we can stand out for his simplicity, and
because it corresponds to a successful approach, the
non relativistic potential models, where quark interaction is modelled using a potential energy in the usual
Schr¨
odinger equation. The literature about quark potentials is huge, so here we add a small number of references [7–15], although incomplete is representative and
is a good starting point to introduce on this topic. One
of the first potential proposed was the Cornell potential
[8, 9], that corresponds to a coulombian potential plus a
linear confinement term. In this way Cornell potential
considers general properties of quark interactions.
Schr¨
odinger equation with Cornell potential do not
have analytical solutions, and although it is possible to
solve it using numerical methods [16, 17], it is always interesting to obtain an approximate analytical solutions
that offer a possibility of additional discussions.
In this work, we solve in an approximate way the
Schr¨
odinger equation with Cornell potential using a procedure that correspond to an adaptation method suggested in [18, 19], that considers usual variational methods with supersymmetric quantum mechanic (SUSY
QM). Some additional examples using SUSY QM and
variational method can be found in [20–22].
The use of SUSY QM [23], born at the beginning of the
eighties in studies of supersymmetry breaking in quantum field theories with extra dimensions [24], allows to
get isospectral potentials to the original potential, with
the particularity that the ground state of the original
potential is not present in the spectrum of isospectral
associated potential, so the ground state of the supersymmetric partner potential is related with the first excited state of original potential.This procedure can be repeated in order to get successive potentials whose ground
states are related by some standard transformations in
SUSY QM, with the different states of the original potential, Cornell in our case. So in this way, if we use the
variational method to get solutions for the ground state
of different supersymmetric partners of the Cornell potential we can obtain the spectrum and wave functions
for heavy quarkonium. Notice that standard variational
method has been used to study heavy quarkonium properties considering different phenomenological quark potentials [25, 26].
The procedure described in the previous paragraph is
used in this work to get approximated eigenvalues and
eigenfunctions for the Schr¨odinger equation with Cornell
potential, and we are using it to study heavy quarkonium
c¯
c, b¯b and b¯
c, paying special attention to the wave function at the origin (WFO), an important quantity that
it is involved in calculations of heavy quarkonium decay
rates.
This paper is structured as follow. In section II we
sumarize the main ingredient of SUSY QM used in this
work. Section III it is dedicated to approximated calculations of energies, wave functions and WFO for heavy
quarkonium using variational method and SUSY QM and
in section IV we discuss our results and conclusions.
MITP/14-070, IFT-UAM/CSIC-14-100, FTUAM-14-38
Precise determination of resonance pole parameters through Pad´
e approximants
Pere Masjuan,1, ∗ Jacobo Ruiz de Elvira,2, † and Juan Jos´e Sanz-Cillero3, ‡
arXiv:1410.2397v1 [hep-ph] 9 Oct 2014
2
1
Institut f¨
ur Kernphysik, Johannes Gutenberg-Universit¨
at, D-55099 Mainz, Germany
Helmholtz-Institut f¨
ur Strahlen- und Kernphysik, Universit¨
at Bonn, D-53115 Bonn, Germany
3
Departamento de F´ısica Te´
orica and Instituto de F´ısica Te´
orica,
IFT-UAM/CSIC Universidad Aut´
onoma de Madrid, Cantoblanco, Madrid, Spain
In this work, we present a precise and model–independent method to extract resonance pole
parameters from phase-shift scattering data. These parameters are defined from the associated
poles in the second Riemann sheet, unfolded by the analytic continuation to the complex pole
using Pad´e approximants. Precise theoretical parameterizations of pion-pion scattering phase shifts
based on once– and twice– subtracted dispersion relations are used as input, whose functional form
allows us to show the benefit and accuracy of the method.
In particular, we extract from these
√
parametrization
the pole positions of the f0 (500) at s = (453 ± 15) − i(297 ± 15) MeV,
√
√ the
ρ(770) at s = (761.4 ± 1.2) − i(71.8 ± 1.0) MeV, and the pole of the f2 (1270), located at s =
(1267.3 ± 1.7) − i(95.0 ± 2.3) MeV. The couplings of the resonances to two pions are also determined
with high precision, obtaining respectively, 3.8±0.4 GeV, 5.92±0.15 and 4.41±0.23 GeV−1 . Special
attention is dedicated to the systematic treatment of the theoretical and statistical uncertainties,
together with their comparison with previous determinations.
PACS numbers: 11.55.-m,11.80.Fv,12.40.Vv,12.40.Yx,13.40.Gp,14.40.-n
Keywords: Pad´
e Approximants, Resonance poles and properties
I.
INTRODUCTION
The non-perturbative regime of Quantum Chromodynamics is characterized by the presence of hadronic
resonances defined by complex S–matrix poles in unphysical Riemann sheets. Contrary to other definitions,
the pole position –and the corresponding pole mass and
width defined by sp = (Mp − iΓp /2)2 – is universal and
independent of the process under consideration. In addition, its residue enclose the information on the underlying process.
However, extrapolating the physical amplitude at real
values of the energy, i.e., in the 1st Riemann sheet, into
the complex plane and extracting resonance poles is not
a trivial task. The extrapolation procedure may change
drastically the value of the outcomes, specially in the
case of broad states.
The simple method proposed here for the analytical
continuation is given by the Pad´e approximants (PA)
to an amplitude F (s) in terms of the total invariant
squared momentum s around a point s0 , denoted by
N
PM
(s, s0 ) [1]:
N
(1)
PM
(s, s0 ) = F (s) + O (s − s0 )M+N +1 ,
N
with PM
(s, s0 ) = QN (s)/RM (s) given by the ratio of
two polynomials QN (s) and RM (s) of degrees N and
M , respectively [1]. RN (s0 ) is chosen to be 1, without
any loss of generality.
∗
†
‡
[email protected]
[email protected]
[email protected]
A special case of interest for the present work is given
by Montessus de Ballore’s theorem [2, 3]. Its simpler
version states that when the amplitude F (s) is analytic
inside the disk Bδ (s0 ) except for a single pole at s = sp
the sequence of one-pole PA P1N (s, s0 ),
P1N (s, s0 )
=
N
−1
X
k=0
ak (s − s0 )k +
aN (s − s0 )N
, (2)
1 − aaNN+1 (s − s0 )
converges to F (s) in any compact subset of the disk
1
F (n) (s0 )
excluding the pole sp . The constants an = n!
th
are given, accordingly, by the n derivative of F (s) [1–
3], being P1N (s, s0 ) determined by the first derivatives
F (0) (s0 ) = F (s0 ), F (1) (s0 )... F (N +1) (s0 ).
Likewise, the PA pole and residue
)
s(N
= s0 +
p
aN
(aN )N +2
, Z (N ) = −
,
aN +1
(aN +1 )N +1
(3)
converge to the corresponding pole and residue of F (s)
for N → ∞.
During the last years, dispersive approaches have
been proved to be a very successful tool to obtain precise
determinations of phase shifts and pole parameters [4–
10]. However, they are based on a complicated although
powerful machinery which makes them difficult to use
except for a limited number of cases. In this letter, we
use dispersive ππ parameterizations to show how it is
possible to obtain a precise and model-independent determination of resonance pole parameters using the theory of PA [1, 3], even for cases where dispersive methods
cannot be easily applied.
Following the proposal in Ref. [3], Montesus’ theorem
is applied to the simplest case with a single-resonance
pole inside the disk Bδ (s0 ). Nonetheless, it can be genN
eralized, ensuring the convergence of the PM
(s, s0 ) se-
arXiv:1410.2376v1 [hep-ph] 9 Oct 2014
Frascati Physics Series Vol. 58 (2014)
Frontier Objects in Astrophysics and Particle Physics
May 18-24, 2014
ARE WE REALLY SEEING DARK MATTER SIGNALS FROM
THE MILKY WAY CENTER?
Germ´
an A. G´omez-Vargas
Instituto de Fis´ıca, Pontificia Universidad Cat´
olica de Chile
INFN, Sezione di Roma “Tor Vergata”
Abstract
The center of the Milky Way is one of the most interesting regions of the γray sky because of the potential for indirect dark matter (DM) detection. It is
also complicated due to the many sources and uncertainties associated with the
diffuse γ-ray emission. Many independent groups have claimed a DM detection
in the data collected by the Large Area Telescope on board the Fermi γ-ray
Satellite from the inner Galaxy region at energies below 10 GeV. However, an
exotic signal needs to be disentangled from the data using a model of known γray emitters, i.e. a background model. We point out that deep understanding
of background ingredients and their main uncertainties is of capital importance
to disentangle a dark matter signal from the Galaxy center.
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–7
Testing the Zee-Babu model via neutrino data, lepton flavour violation and direct
searches at the LHC
Juan Herrero-Garciaa , Miguel Nebotb , Nuria Riusc and Arcadi Santamariac
arXiv:1410.2299v1 [hep-ph] 8 Oct 2014
a
Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology,
AlbaNova University Center, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
b Centro de F´ısica Te´
orica de Part´ıculas, Instituto Superior T´ecnico – Universidade de Lisboa,
Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
c Departamento de F´ısica Te´
orica, Universidad de Valencia and IFIC, Universidad de Valencia-CSIC,
C/ Catedr´atico Jos´e Beltr´an, 2 — E-46980 Paterna, Spain
Abstract
In this talk we discuss how the Zee-Babu model can be tested combining information from neutrino data, low-energy
experiments and direct searches at the LHC. We update previous analysis in the light of the recent measurement of
the neutrino mixing angle θ13 [1], the new MEG limits on µ → eγ [2], the lower bounds on doubly-charged scalars
coming from LHC data [3, 4], and, of course, the discovery of a 125 GeV Higgs boson by ATLAS and CMS [5, 6].
In particular, we find that the new singly- and doubly-charged scalars are accessible at the second run of the LHC,
yielding different signatures depending on the neutrino hierarchy and on the values of the phases. We also discuss in
detail the stability of the potential.
Keywords: Neutrino masses, Lepton flavor violation, LHC, stability of the potential
1. Introduction
Radiative models are a very plausible way in which
neutrinos may acquire their tiny masses: ν’s are light because they are massless at tree level, with their masses
being generated by loop corrections that generically
have the following form:
v2
mν ∼ c
,
(4π)2i Λ
(1)
where c encodes some lepton number violating (LNV)
couplings and/or ratios of masses, Λ is the scale of LNV
which can be at the TeV and therefore can be accessible at colliders, and i are the number of loops, where
typically more than three loops yield too light neutrino
masses or have problems with low-energy constraints
(so typically i < 4).
In the Zee-Babu model [7, 8, 9, 10, 11, 12, 13, 14, 15]
neutrino masses are generated at two loops, where the
new scalars cannot be very heavy or have very small
Yukawa couplings, otherwise neutrino masses would be
too small.
We follow the notation in [12, 15], where a complete
list of references is given. The Zee-Babu adds to the
Standard Model two charged singlet scalar fields
h± ,
k±± ,
(2)
with weak hypercharges ±1 and ±2 respectively.
The interesting Yukawa interactions are:
LY = ` Yeφ + `˜ f `h+ + ec g e k++ + H.c.
(3)
Due to Fermi statistics, fab is an antisymmetric matrix
in flavour space, while gab is symmetric.
And the most general scalar potential has the form:
V
=
†
02 2
02 2
m02
H H H + mh |h| + mk |k| +
+
λH (H † H)2 + λh |h|4 + λk |k|4 +
Symmetry Energy Effects on the Nuclear Landscape
Rui Wang1 and Lie-Wen Chen∗1, 2
1
arXiv:1410.2498v1 [nucl-th] 9 Oct 2014
Department of Physics and Astronomy and Shanghai Key Laboratory for Particle Physics and Cosmology,
Shanghai Jiao Tong University, Shanghai 200240, China
2
Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, China
(Dated: October 10, 2014)
While various mean-field models predict similar two-proton drip line in the nuclear landscape, their
predictions for the two-neutron drip line involve extreme extrapolations and exhibit a significant
variation. We demonstrate that this variation is mainly due to the different values of the symmetry
energy Esym (ρc ) at the subsaturation cross density ρc ≈ 0.11 fm−3 for different interactions. Based
on the recent accurate constraint on Esym (ρc ), we obtain a quite precise prediction for the location
of the two-neutron drip line and thus a very precise estimate of 1981 ± 76 for the number of bound
even-even nuclei with proton number between 2 and 120 among which only 799 have so far been
discovered experimentally.
PACS numbers: 21.65.Ef, 21.10.Dr, 21.30.Fe, 21.60.Jz
The determination of the location of neutron and proton drip lines in the nuclear landscape is a fundamental
question in nuclear physics. The drip lines tell us what
the limit of the nuclear stability is and how many bound
nuclei can exist in the nuclear chart [1]. The quest for
the neutron drip line is critically important for understanding the astrophysical rapid neutron capture process
(r-process) which provides a nucleosynthesis mechanism
for the origin of more than half of the heavy nuclei in the
Universe [2, 3]. While the proton drip line has been determined up to Protactinium (proton number Z = 91) [4],
there has little experimental information on the neutron
drip line for elements with Z > 8 [5], and this provides a
strong motivation for the research on radioactive nuclei
at rare isotope beam facilities [6].
Information on the neutron drip line significantly relies on model extrapolation. Theoretically, the drip lines
can be predicted either from macroscopic models [7, 8]
or from microscopic density functional theory (DFT) [9–
16] based on the self-consistent mean-field. Especially,
benchmark calculations have been recently performed to
predict the two-nucleon drip lines within DFT using advanced non-relativistic and relativistic (covariant) interactions [17–20]. Although these theoretical approaches
have achieved remarkable success in describing the data
on known nuclei, extrapolations to unknown nuclei appears less certain. Different approaches or interactions,
which predict similar two-proton drip line, can give quite
different predictions for the position of the two-neutron
drip line [17–20]. Physically this uncertainty is mainly
due to our poor knowledge on the isovector effective interactions since the nuclei close to the neutron drip line
have extremely large isospin values [17–20]. The symmetry energy Esym (ρ), which characterizes the isospin
dependent part of the equation of state (EOS) of asymmetric nuclear matter, is an important quantity to reflect
the nature of the isovector effective interactions (see, e.g.,
Ref. [21]). It is thus essential to find out the relation between the symmetry energy and the predicted drip lines
which will be critically useful for improving our predictions for the properties of extremely neutron-rich nuclei.
Unfortunately, so far this relationship is still largely controversial and elusive. Indeed, Oyamatsu et al. [8] found
that the location of the neutron drip line is sensitive to
the density slope L(ρ0 ) of the symmetry energy at saturation density ρ0 . However, a recent work by Afanasjev et
al. [19] (see also Ref. [20]) indicates that there exists no
such a correlation. In this work, we demonstrate that the
location of the neutron drip line is strongly correlated
with the magnitude of the symmetry energy at the subsaturation cross density ρc ≈ 0.11 fm−3 , i.e., Esym (ρc ),
although it essentially exhibits no correlation with L(ρ0 )
or Esym (ρ0 ). With the help of the recent accurately determined Esym (ρc ), this finding significantly reduces the
uncertainly in the theoretical prediction on the location
of the neutron drip line.
The symmetry energy plays multifaceted roles in nuclear physics and astrophysics [21–28] as well as new
physics beyond the standard model [29–33], and it is de2
1 ∂ E(ρ,δ)
fined as Esym (ρ) = 2!
|δ=0 via an expansion of the
∂δ 2
nucleon specific energy (i.e., EOS) in an asymmetric nuclear matter, i.e., E(ρ, δ) = E0 (ρ) + Esym (ρ)δ 2 + O(δ 4 )
where ρ is the baryon density and δ = (ρn −ρp )/(ρp +ρn )
is the isospin asymmetry. The E0 (ρ) represents the EOS
of symmetric nuclear matter and can be expanded around
ρ−ρ0 3
0 2
ρ0 as E0 (ρ) = E0 (ρ0 ) + K2!0 ( ρ−ρ
3ρ0 ) + O(( 3ρ0 ) ) where
the K0 is the incompressibility coefficient of symmetric
nuclear matter. The symmetry energy Esym (ρ) can also
be expanded around a reference density ρr as
Esym (ρ) = Esym (ρr ) + L(ρr )χr + O(χ2r ),
∗ Corresponding
author (email: [email protected])
with χr =
ρ−ρr
3ρr .
(1)
The coefficient L(ρr ) denotes the density
Beyond mean-field study of elastic and inelastic electron scattering off nuclei
J. M. Yao∗ ,1, 2 M. Bender,3, 4 and P.-H. Heenen1
1
Physique Nucl´eaire Th´eorique, Universit´e Libre de Bruxelles, C.P. 229, B-1050 Bruxelles, Belgium
2
School of Physical Science and Technology, Southwest University, Chongqing, 400715 China
3
Universit´e de Bordeaux, Centre d’Etudes Nucl´eaires de Bordeaux Gradignan, UMR5797, F-33175 Gradignan, France
4
CNRS/IN2P3, Centre d’Etudes Nucl´eaires de Bordeaux Gradignan, UMR5797, F-33175 Gradignan, France
(Dated: 8 October 2014)
arXiv:1410.2389v1 [nucl-th] 9 Oct 2014
Background Electron scattering provides a powerful tool to determine charge distributions and transition densities of nuclei.
This tool will soon be available for short-lived neutron-rich nuclei.
Purpose Beyond mean-field methods have been successfully applied to the study of excitation spectra of nuclei in the whole
nuclear chart. These methods permit to determine energies and transition probabilities starting from an effective inmedium nucleon-nucleon interaction but without other phenomenological ingredients. Such a method has recently been
extended to calculate the charge density of nuclei deformed at the mean-field level of approximation [J. M. Yao et al.,
Phys. Rev. C 86, 014310 (2012)]. The aim of this work is to further extend the method to the determination of transition
densities between low-lying excited states.
Method The starting point of our method is a set of Hartree-Fock-Bogoliubov wave functions generated with a constraint
on the axial quadrupole moment and using a Skyrme energy density functional. Correlations beyond the mean field
are introduced by projecting mean-field wave functions on angular-momentum and particle number and by mixing the
symmetry restored wave functions.
Results We give in this paper detailed formulae derived for the calculation of densities and form factors. These formulae are
rather easy to obtain when both initial and final states are 0+ states but are far from being trivial when one of the states
has a finite J-value. Illustrative applications to 24 Mg and to the even-mass 58−68 Ni have permitted to analyse the main
features of our method, in particular the effect of deformation on densities and form factors. An illustration calculation
of both elastic and inelastic scattering form factors is presented.
Conclusions We present a very general framework to calculate densities of and transition densities between low-lying states
that can be applied to any nucleus. To achieve better agreement with the experimental data will require to improve the
energy density functionals that are currently used and also to introduce quasi-particle excitations in the mean-field wave
functions.
PACS numbers: 21.10.Ft, 21.10.Ky, 21.60.Jz, 25.30.Bf, 25.30.Dh
I.
INTRODUCTION
Electron scattering off nuclei is a powerful tool for studies of nuclear structure and spectroscopy [1–16]. It allows
to determine the charge distribution of nuclear ground
states, as well as of the transition charge and current
densities from the ground state to excited states. More
global properties can be extracted from a detailed knowledge of charge distribution, like charge radii. Parameters
characterizing the extension and surface thickness of the
nuclear density can also be derived [17, 18]. From the
form factors for inelastic electron scattering at low transferred momentum q, the spin and parity of excited states
and the multipole transition strengths can be determined
in a model-independent manner [4, 10]. At larger values
of q, the form factors present an insight into the spatial location of the transition process, which cannot be
accessed from the integral over this function provided by
the measurement of B(EL) values in Coulomb excitation
or lifetime measurements. Thereby, electron scattering
does not only provide a powerful alternative to many
∗ Present address: Department of Physics, Tohoku University,
Sendai 980-8578, Japan
other types of nuclear structure studies, but also complements them by giving access to levels and transitions
that are undetectable in photoexcitation and γ-ray spectroscopy, such as for instance levels excited by monopole
transitions or transitions of high multipolarity.
As all electron-nucleus scattering experiments of the
past used fixed or gas targets, only stable and a very
few long-lived nuclides could be studied so far. This
will change with the set-up of electron-RIB collider experiments. The SCRIT (Self Confining Radioactive Isotope Target) project [19–21] is under construction at
RIKEN (Japan) and the ELISe (ELectron-Ion Scattering in a storage ring) project is planned for FAIR (Germany) [22, 23]. When being realised, the charge densities
and transition charge densities of short-lived nuclides, in
particular neutron-rich nuclei, will be measured at both
installations.
Data from electron scattering are often interpreted in
terms of parameterized macroscopic density and transition density distributions, such as the ones of Helm [24],
Tassie [25] or Friedrich et al. [17, 18]. They all have in
common that some functional form of the ground-state or
transition charge densities is postulated and its parameters adjusted to reproduce the data. Such analysis provides an insight into the gross features of the ground state
and transition charge density distribution and the reso-
arXiv:1410.2062v1 [nucl-th] 8 Oct 2014
Resonance dynamics in the coherent η meson production in the
(p, p′) reaction on the spin-isospin saturated nucleus
Swapan Das 1
Nuclear Physics Division, Bhabha Atomic Research Centre
Mumbai-400085, India
Abstract
For the forward going proton and η meson, the coherent η meson production in
the (p, p′ ) reaction on the spin-isospin saturated nucleus occurs only due to the η
meson exchange interaction between the beam proton and nucleus. In this process,
the nucleon in the nucleus can be excited to resonances N ∗ and the η meson in the
final state can arise due to N ∗ → N η. We investigate the dynamics of resonances,
including nucleon Born terms, and their interferences in the coherently added cross
section of this reaction. We discuss the importance of N (1520) resonance and show
the sensitivity of the cross section to the hadron nucleus interaction.
Keywords: η meson exchange interaction, N ∗ propagation
PACS number(s): 25.40e, 13.30.Eg, 13.60.Le
The coherent meson production in the nuclear reaction is a potential tool to investigate
the resonance dynamics in the nucleus, as well as the meson nucleus interaction in the
final state. Since the branching ratio of ∆(1232) → Nπ is ≃ 100% [1], the coherent pion
production process has been used extensively to investigate the ∆ dynamics in the nucleus
[2, 3]. This process in (γ, π) and (e, eπ) reactions is used to study the transverse N → ∆
excitation in the nucleus, where the coherent pion is produced away from the forward
direction [4]. The forward emission of coherent pion is a probe for the longitudinal ∆
excitation which occur in the pion nuclear reaction [5].
The coherent pion production is also studied in the proton and ion induced nuclear
reaction [6, 7]. The issue of ∆-peak shift in the nucleus [8] is resolved, as it occurs because
of the coherent pion production [6, 7] which is not possible for proton target. The coherent
pion production in the (p, n) [6] and (3 He, t) [7] reactions on the nucleus is shown to have
one to one correspondence with that in the π + meson nucleus scattering [9, 10]. For the
forward going protons, the coherent pion production in the (p, p′ ) reaction can be used to
produce π 0 beam [11] which is analogous to tagged photon beam.
The coherent η meson production in the nuclear reaction is another process which can
be used to study the resonance dynamics in the nucleus. Amongst the resonances, N(1535)
has large decay branching ratio (42%) in the Nη channel, i.e., ΓN (1535)→N η (m = 1535 MeV)
1
email: [email protected]
1
Blast Wave Fits to Elliptic Flow Data at
√
sNN = 7.7–2760 GeV
X. Sun1,2 , H. Masui3 , A. M. Poskanzer2 , and A. Schmah2
1
2
Department of Physics, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and
3
Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan
arXiv:1410.1947v1 [hep-ph] 8 Oct 2014
We present blast wave fits to elliptic flow (v2 (pT )) data in minimum bias collisions from the
√
sNN = 7.7–200 GeV at RHIC, and 2.76 TeV at LHC. The fits are performed separately for
particles and corresponding anti-particles. The mean transverse velocity parameter β shows an
energy dependent difference between particles and corresponding anti-particles, which increases as
the beam energy decreases. Possible effects of feed down, baryon stopping, anti-particle absorption,
and early production times for anti-particles are discussed.
I.
INTRODUCTION
To understand the formation of the Quark-Gluon
Plasma (QGP) phase and to study the structure of the
QCD phase diagram, a Beam Energy Scan (BES) program was started in the years 2010 and 2011 at the Relativistic Heavy Ion Collider (RHIC) facility [1] where
√
Au+Au collisions were recorded at sNN = 7.7, 11.5,
19.6, 27, 39, and 62.4 GeV. Azimuthal anisotropy [2] is
one of the most important observables for relativistic nuclear collisions to study the bulk behavior of the created
matter. In non-central Au+Au collision, the overlap region has an almond shape with the major axis perpendicular to the reaction plane, which is defined by the impact
parameter and the beam direction. Due to fluctuations,
the participant plane [3] in each event is not necessarily
the same as the reaction plane. As the system evolves,
the pressure gradient converts the anisotropy from coordinate space to momentum space. The produced particle
distribution [4, 5] can be written as:
E
∞
X
d3 N
1
d2 N
2vnobs cos[n(φ−Ψn )]), (1)
=
(1+
dp3
2π pT dpT dy
n=1
vn = vnobs /Rn ,
(2)
where φ is the azimuthal angle of a particle, Ψn is the
n-th harmonic event plane angle reconstructed by the observed particles, which is an estimation of the participant
plane, and Rn is the n-th harmonic event plane resolution. The second harmonic coefficient v2 reported here is
called elliptic flow.
Several interesting observations related to v2 have been
reported in the past decade by using data from the top
√
RHIC energy of sNN = 200 GeV [2, 6–9]. At low transverse momenta (pT < 2.0 GeV/c), a mass ordering of
the v2 values was observed [10–12], which could be understood within a hydrodynamic framework. At intermediate pT range, (2 < pT < 6 GeV/c), a Number-ofConstituent Quark (NCQ) scaling [13] of v2 for identified hadrons was observed. This observation, coupled
with comparable values of the elliptic flow measured for
multi-strange hadrons (φ and Ξ) and light quark hadrons,
was used to conclude that the relevant degrees of freedom are quarks and gluons for the matter formed in
the early stage of heavy ion collisions at top RHIC energy [2, 12, 14–16].
The mass ordering in the low pT range and the NCQ
scaling in the intermediate pT range were also observed
in BES experiments [17]. In this paper we use the blast
√
wave model [18–22] to fit v2 (pT ) data at sNN = 7.7 –
2760 GeV to get the energy dependence of the mean radial flow expansion velocity. The blast wave model is an
approximation to the full hydro calculations, which were
only done for BES inclusive charged hadron data [23],
not for identified particles due to complications of the
equation-of-state and the initial conditions.
This paper is organized as follows. Section II gives
a brief introduction to the blast wave model and the fit
functions used in this paper. In Section III we show the fit
results and discuss the physics implications. A summary
is given in Section IV.
II.
BLAST WAVE PARAMETRIZATION
A nuclear fireball model [18] was introduced by Westfall et al. to explain midrapidity proton inclusive spectra.
This model assumes that a clean cylindrical cut is made
by the projectile and target and leave a hot souce in between. Protons emitted from the fireball should follow
a thermal energy distribution. Soon after, Siemens and
Rasmussen generalized a relativistic kinematics formula
of blast wave parametrization by assuming an exploding
fireball producing a blast wave of nucleons and pions [19].
Two decades ago, Schnedermann et al. introduced a simple functional form with only two fit parameters: a kinetic temperature (T ) and a radial velocity (β) which
was successfully used in fits to pT spectra [20]. Huovinen
et al. [21] introduced a third parameter, the difference
of the radial velocity in and out of the reaction plane,
in the equation to discribe transversely anisotropic flow
generated in non-central collisions.
However, the blast wave fit matched data even better
after the STAR Collaboration added a fourth parameter [22] to take into account the anisotropic shape of the
source in coordinate space.
Nuclear
Physics A
Nuclear Physics A 00 (2014) 1–4
Measurements of b-jet Nuclear Modification Factors in pPb and
PbPb Collisions with CMS
arXiv:1410.2576v1 [nucl-ex] 9 Oct 2014
Kurt Jung (for the CMS Collaboration)1
Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave., West Lafayette, IN, USA
Abstract
HIA
We present measurements of the nuclear modification factors RAA and RPYT
of b jets in lead-lead and proton-lead collisions,
pA
respectively, using the CMS detector. Jets from b-quark fragmentations are found by exploiting the long lifetime of the b-quark
through tagging methods using distributions of the secondary vertex displacement. From these, b-jet cross-sections are calculated
and compared to the pp cross-section from the 2.76 TeV pp data collected in 2013 and to a PYTHIA simulation at 5.02 TeV, where
these center-of-mass energies correspond to those of the PbPb and pPb data. We observe significant suppression for b jets in PbPb,
HIA
and a RPYT
value consistent with unity for b jets in pPb. Results from both collision species show remarkable correspondance
pA
with inclusive-jet suppression measurements, indicating that mass-dependent energy-loss effects are negligible at pT values greater
than around 50 GeV/c. We use 150 µb−1 of lead-lead data and 35 nb−1 of proton-lead data collected at the LHC.
Keywords: QGP, b jets, energy-loss
1. Introduction
Quenching of jets in heavy-ion collisions is expected to depend heavily on the mass of the fragmenting parton.
Under the assumption that gluon radiation is the dominant energy-loss mechanism, jets from heavy quarks are expected to radiate less due to the “dead-cone effect”, especially when the parton pT is comparible to the parton mass.
It must be said, however, that the mechanisms for in-medium partonic energy-loss are still poorly constrained. These
measurements of the energy loss observed in jets from heavy-ion collisions as a function of jet flavor provide powerful
constraints on the understanding of possible energy-loss mechanisms, as jet flavor is a direct proxy for the different
parton masses. This analysis will focus on b-jet energy loss.
CMS is described in detail in the original detector publication [1], and its silicon tracker and hadronic calorimeter
are excellent experimental tools for observing heavy flavor jets in heavy-ion collisons. Jets formed from heavy flavor
quark fragmentation are typically tagged in one of two ways: first, by the direct reconstruction of a displaced vertex,
and second by the displacement of individual tracks. Using the track-only tagging method as a cross-check ensures
the secondary vertex reconstruction selections remain unbiased. The three-dimensional distance of the closest track
point to the primary vertex is defined as the impact parameter [2]. Information from these tracks and vertices are
typically combined into a quantity which optimizes their discrimination between heavy and light flavor jets. In this
analysis, we use a discriminator to tag b jets which is based on the displacement of the reconstructed secondary
vertex (SV) with respect to the primary vertex of the interaction. This discriminator is called the Simple Secondary
Vertex tagger (SSV) [2], and is based on the displacement significance (displacement divided by its uncertainty) of
1A
list of members of the CMS Collaboration and acknowledgements can be found at the end of this issue.
1
arXiv:1410.2559v1 [nucl-ex] 9 Oct 2014
Beam-energy and system-size dependence of the space-time extent of the pion
emission source produced in heavy ion collisions
A. Adare,13 S. Afanasiev,32 C. Aidala,14, 41, 45, 46 N.N. Ajitanand,64 Y. Akiba,58, 59 R. Akimoto,12 H. Al-Bataineh,52
H. Al-Ta’ani,52 J. Alexander,64 M. Alfred,25 A. Angerami,14 K. Aoki,37, 58 N. Apadula,30, 65 L. Aphecetche,66
Y. Aramaki,12, 58 R. Armendariz,52 S.H. Aronson,7 J. Asai,59 H. Asano,37, 58 E.C. Aschenauer,7 E.T. Atomssa,38, 65
R. Averbeck,65 T.C. Awes,54 B. Azmoun,7 V. Babintsev,26 M. Bai,6 G. Baksay,20 L. Baksay,20 A. Baldisseri,16
N.S. Bandara,45 B. Bannier,65 K.N. Barish,8 P.D. Barnes,41, ∗ B. Bassalleck,51 A.T. Basye,1 S. Bathe,5, 8, 59
S. Batsouli,54 V. Baublis,57 C. Baumann,47 S. Baumgart,58 A. Bazilevsky,7 M. Beaumier,8 S. Beckman,13
S. Belikov,7, ∗ R. Belmont,46, 70 R. Bennett,65 A. Berdnikov,61 Y. Berdnikov,61 A.A. Bickley,13 X. Bing,53
D. Black,8 D.S. Blau,36 J.G. Boissevain,41 J. Bok,52 J.S. Bok,74 H. Borel,16 K. Boyle,59, 65 M.L. Brooks,41
J. Bryslawskyj,5 H. Buesching,7 V. Bumazhnov,26 G. Bunce,7, 59 S. Butsyk,41, 51, 65 C.M. Camacho,41
S. Campbell,30, 65 P. Castera,65 B.S. Chang,74 J.-L. Charvet,16 C.-H. Chen,59, 65 S. Chernichenko,26 C.Y. Chi,14
J. Chiba,34 M. Chiu,7, 27 I.J. Choi,27, 74 J.B. Choi,10 S. Choi,63 R.K. Choudhury,4 P. Christiansen,43 T. Chujo,69, 70
P. Chung,64 A. Churyn,26 O. Chvala,8 V. Cianciolo,54 Z. Citron,65, 72 C.R. Cleven,22 B.A. Cole,14 M.P. Comets,55
M. Connors,65 P. Constantin,41 M. Csan´
ad,18 T. Cs¨org˝
o,73 T. Dahms,65 S. Dairaku,37, 58 I. Danchev,70 K. Das,21
A. Datta,45, 51 M.S. Daugherity,1 G. David,7 M.B. Deaton,1 K. DeBlasio,51 K. Dehmelt,20, 65 H. Delagrange,66
A. Denisov,26 D. d’Enterria,14 A. Deshpande,59, 65 E.J. Desmond,7 K.V. Dharmawardane,52 O. Dietzsch,62
L. Ding,30 A. Dion,30, 65 J.H. Do,74 M. Donadelli,62 O. Drapier,38 A. Drees,65 K.A. Drees,6 A.K. Dubey,72
J.M. Durham,41, 65 A. Durum,26 D. Dutta,4 V. Dzhordzhadze,8 L. D’Orazio,44 S. Edwards,6, 21 Y.V. Efremenko,54
J. Egdemir,65 F. Ellinghaus,13 W.S. Emam,8 T. Engelmore,14 A. Enokizono,40, 54, 58, 60 H. En’yo,58, 59 S. Esumi,69
K.O. Eyser,8 B. Fadem,48 N. Feege,65 D.E. Fields,51, 59 M. Finger,9, 32 M. Finger, Jr.,9, 32 F. Fleuret,38 S.L. Fokin,36
Z. Fraenkel,72, ∗ J.E. Frantz,53, 65 A. Franz,7 A.D. Frawley,21 K. Fujiwara,58 Y. Fukao,37, 58 T. Fusayasu,50
S. Gadrat,42 K. Gainey,1 C. Gal,65 P. Gallus,15 P. Garg,3 A. Garishvili,67 I. Garishvili,40, 67 H. Ge,65 F. Giordano,27
A. Glenn,13, 40 H. Gong,65 X. Gong,64 M. Gonin,38 J. Gosset,16 Y. Goto,58, 59 R. Granier de Cassagnac,38
N. Grau,2, 14, 30 S.V. Greene,70 M. Grosse Perdekamp,27, 59 Y. Gu,64 T. Gunji,12 L. Guo,41 H. Guragain,22
H.-˚
A. Gustafsson,43, ∗ T. Hachiya,24, 58 A. Hadj Henni,66 C. Haegemann,51 J.S. Haggerty,7 K.I. Hahn,19
H. Hamagaki,12 J. Hamblen,67 R. Han,56 S.Y. Han,19 J. Hanks,14, 65 H. Harada,24 E.P. Hartouni,40 K. Haruna,24
S. Hasegawa,31 K. Hashimoto,58, 60 E. Haslum,43 R. Hayano,12 X. He,22 M. Heffner,40 T.K. Hemmick,65 T. Hester,8
H. Hiejima,27 J.C. Hill,30 R. Hobbs,51 M. Hohlmann,20 R.S. Hollis,8 W. Holzmann,14, 64 K. Homma,24 B. Hong,35
T. Horaguchi,24, 58, 68, 69 Y. Hori,12 D. Hornback,67 T. Hoshino,24 J. Huang,7 S. Huang,70 T. Ichihara,58, 59
R. Ichimiya,58 J. Ide,48 H. Iinuma,34, 37, 58 Y. Ikeda,58, 69 K. Imai,31, 37, 58 Y. Imazu,58 J. Imrek,17 M. Inaba,69
Y. Inoue,58, 60 A. Iordanova,8 D. Isenhower,1 L. Isenhower,1 M. Ishihara,58 T. Isobe,12, 58 M. Issah,64, 70 A. Isupov,32
D. Ivanischev,57 D. Ivanishchev,57 B.V. Jacak,65 M. Javani,22 S.J. Jeon,49 M. Jezghani,22 J. Jia,7, 14, 64 X. Jiang,41
J. Jin,14 O. Jinnouchi,59 B.M. Johnson,7 E. Joo,35 K.S. Joo,49 D. Jouan,55 D.S. Jumper,1, 27 F. Kajihara,12
S. Kametani,12, 58, 71 N. Kamihara,58, 59 J. Kamin,65 M. Kaneta,59 S. Kaneti,65 B.H. Kang,23 J.H. Kang,74
J.S. Kang,23 H. Kanou,58, 68 J. Kapustinsky,41 K. Karatsu,37, 58 M. Kasai,58, 60 D. Kawall,45, 59 M. Kawashima,58, 60
A.V. Kazantsev,36 T. Kempel,30 J.A. Key,51 V. Khachatryan,65 A. Khanzadeev,57 K. Kihara,69 K.M. Kijima,24
J. Kikuchi,71 B.I. Kim,35 C. Kim,35 D.H. Kim,19, 49 D.J. Kim,33, 74 E. Kim,63 E.-J. Kim,10 H.-J. Kim,74 H.J. Kim,74
´ Kiss,18 E. Kistenev,7
K.-B. Kim,10 M. Kim,63 S.H. Kim,74 Y.-J. Kim,27 Y.K. Kim,23 E. Kinney,13 K. Kiriluk,13 A.
A. Kiyomichi,58 J. Klatsky,21 J. Klay,40 C. Klein-Boesing,47 D. Kleinjan,8 P. Kline,65 T. Koblesky,13 L. Kochenda,57
V. Kochetkov,26 M. Kofarago,18 Y. Komatsu,12 B. Komkov,57 M. Konno,69 J. Koster,27, 59 D. Kotchetkov,8, 51, 53
D. Kotov,57, 61 A. Kozlov,72 A. Kr´al,15 A. Kravitz,14 F. Krizek,33 J. Kubart,9, 29 G.J. Kunde,41 N. Kurihara,12
K. Kurita,58, 60 M. Kurosawa,58, 59 M.J. Kweon,35 Y. Kwon,67, 74 G.S. Kyle,52 R. Lacey,64 Y.S. Lai,14 J.G. Lajoie,30
A. Lebedev,30 B. Lee,23 D.M. Lee,41 J. Lee,19 K. Lee,63 K.B. Lee,35, 41 K.S. Lee,35 M.K. Lee,74 S.H. Lee,65
S.R. Lee,10 T. Lee,63 M.J. Leitch,41 M.A.L. Leite,62 M. Leitgab,27 E. Leitner,70 B. Lenzi,62 B. Lewis,65 X. Li,11
P. Liebing,59 S.H. Lim,74 L.A. Linden Levy,13 T. Liˇska,15 A. Litvinenko,32 H. Liu,41, 52 M.X. Liu,41 B. Love,70
R. Luechtenborg,47 D. Lynch,7 C.F. Maguire,70 Y.I. Makdisi,6 M. Makek,72, 75 A. Malakhov,32 M.D. Malik,51
A. Manion,65 V.I. Manko,36 E. Mannel,7, 14 Y. Mao,56, 58 L. Maˇsek,9, 29 H. Masui,69 S. Masumoto,12 F. Matathias,14
M. McCumber,13, 41, 65 P.L. McGaughey,41 D. McGlinchey,13, 21 C. McKinney,27 N. Means,65 A. Meles,52
M. Mendoza,8 B. Meredith,14, 27 Y. Miake,69 T. Mibe,34 A.C. Mignerey,44 P. Mikeˇs,9, 29 K. Miki,58, 69 A.J. Miller,1
3
19
Ewha Womans University, Seoul 120-750, Korea
Florida Institute of Technology, Melbourne, Florida 32901, USA
21
Florida State University, Tallahassee, Florida 32306, USA
22
Georgia State University, Atlanta, Georgia 30303, USA
23
Hanyang University, Seoul 133-792, Korea
24
Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan
25
Department of Physics and Astronomy, Howard University, Washington, DC 20059, USA
26
IHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, Russia
27
University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
28
Institute for Nuclear Research of the Russian Academy of Sciences, prospekt 60-letiya Oktyabrya 7a, Moscow 117312, Russia
29
Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
30
Iowa State University, Ames, Iowa 50011, USA
31
Advanced Science Research Center, Japan Atomic Energy Agency, 2-4
Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan
32
Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia
33
Helsinki Institute of Physics and University of Jyv¨
askyl¨
a, P.O.Box 35, FI-40014 Jyv¨
askyl¨
a, Finland
34
KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
35
Korea University, Seoul, 136-701, Korea
36
Russian Research Center “Kurchatov Institute,” Moscow, 123098 Russia
37
Kyoto University, Kyoto 606-8502, Japan
38
Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, France
39
Physics Department, Lahore University of Management Sciences, Lahore 54792, Pakistan
40
Lawrence Livermore National Laboratory, Livermore, California 94550, USA
41
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
42
LPC, Universit´e Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, France
43
Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden
44
University of Maryland, College Park, Maryland 20742, USA
45
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337, USA
46
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
47
Institut f¨
ur Kernphysik, University of Muenster, D-48149 Muenster, Germany
48
Muhlenberg College, Allentown, Pennsylvania 18104-5586, USA
49
Myongji University, Yongin, Kyonggido 449-728, Korea
50
Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, Japan
51
University of New Mexico, Albuquerque, New Mexico 87131, USA
52
New Mexico State University, Las Cruces, New Mexico 88003, USA
53
Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
54
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
55
IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, France
56
Peking University, Beijing 100871, People’s Republic of China
57
PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad Region, 188300, Russia
58
RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
59
RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
60
Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan
61
Saint Petersburg State Polytechnic University, St. Petersburg, 195251 Russia
62
Universidade de S˜
ao Paulo, Instituto de F´ısica, Caixa Postal 66318, S˜
ao Paulo CEP05315-970, Brazil
63
Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Korea
64
Chemistry Department, Stony Brook University, SUNY, Stony Brook, New York 11794-3400, USA
65
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
66
SUBATECH (Ecole des Mines de Nantes, CNRS-IN2P3, Universit´e de Nantes) BP 20722 - 44307, Nantes, France
67
University of Tennessee, Knoxville, Tennessee 37996, USA
68
Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan
69
Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, Japan
70
Vanderbilt University, Nashville, Tennessee 37235, USA
71
Waseda University, Advanced Research Institute for Science and
Engineering, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan
72
Weizmann Institute, Rehovot 76100, Israel
73
Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, Hungarian
Academy of Sciences (Wigner RCP, RMKI) H-1525 Budapest 114, POBox 49, Budapest, Hungary
74
Yonsei University, IPAP, Seoul 120-749, Korea
75
University of Zagreb, Faculty of Science, Department of Physics, Bijeniˇcka 32, HR-10002 Zagreb, Croatia
(Dated: October 10, 2014)
20