1. No category

EPJ manuscript No.
(will be inserted by the editor)
arXiv:1411.2888v1 [nucl-ex] 11 Nov 2014
A new study of the 22Ne(p,γ)23Na reaction deep underground:
Feasibility, setup, and first observation of the 186 keV resonance
F. Cavanna1 , R. Depalo2,3 , M.-L. Menzel4,5 , M. Aliotta6 , M. Anders4,5 D. Bemmerer4 a , C. Broggini2 , C.G. Bruno6 ,
A. Caciolli3,2 , P. Corvisiero1, T. Davinson6 , A. di Leva7 , Z. Elekes8 , F. Ferraro1 A. Formicola9 , Zs. F¨
ul¨op8 , G. Gervino10 ,
11
12
8
7
9
2
A. Guglielmetti , C. Gustavino , Gy. Gy¨
urky , G. Imbriani , M. Junker , R. Menegazzo , P. Prati1 , C. Rossi Alvarez2 ,
D.A. Scott6 , E. Somorjai8 , O. Straniero13 , F. Strieder14 , T. Sz¨
ucs4 , and D. Trezzi11 (LUNA collaboration)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Dipartimento di Fisica, Universit`
a di Genova, and Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Genova, Italy
INFN Sezione di Padova, Padova, Italy
Dipartimento di Fisica e Astronomia, Universit`
a di Padova, Padova, Italy
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany
Technische Universit¨
at Dresden, Dresden, Germany
SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
Dipartimento di Fisica, Universit`
a degli Studi di Napoli Federico II, and INFN Sezione di Napoli, Napoli, Italy
Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA ATOMKI), Debrecen, Hungary
INFN, Laboratori Nazionali del Gran Sasso, Assergi, Italy
Dipartimento di Fisica Sperimentale, Universit`
a di Torino, and INFN Sezione di Torino, Torino, Italy
Universit`
a degli Studi di Milano, and INFN Sezione di Milano, Milano, Italy
INFN Sezione di Roma “La Sapienza”, Roma, Italy,
Osservatorio Astronomico di Collurania, Teramo, and INFN Sezione di Napoli, Napoli, Italy
Ruhr-Universit¨
at Bochum, Bochum, Germany
November 12, 2014
Abstract. The 22 Ne(p,γ)23 Na reaction takes part in the neon-sodium cycle of hydrogen burning. This
cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis
of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields,
new experimental efforts to measure the 22 Ne(p,γ)23 Na cross section directly at the astrophysically relevant energies are needed. In the present work, a feasibility study for a 22 Ne(p,γ)23 Na experiment at the
Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator deep underground in the
Gran Sasso laboratory, Italy, is reported. The ion beam induced γ-ray background has been studied. The
feasibility study led to the first observation of the Ep = 186 keV resonance in a direct experiment. An
experimental lower limit of 0.12 × 10−6 eV has been obtained for the resonance strength. Informed by the
feasibility study, a dedicated experimental setup for the 22 Ne(p,γ)23 Na experiment has been developed.
The new setup has been characterized by a study of the temperature and pressure profiles. The beam
heating effect that reduces the effective neon gas density due to the heating by the incident proton beam
has been studied using the resonance scan technique, and the size of this effect has been determined for a
neon gas target.
PACS. 26.30.-k Nucleosynthesis in novae, supernovae, and other explosive stars – 25.40.Ep Inelastic
proton scattering – 29.30.Kv X- and gamma-ray spectroscopy – 51.20.+d Viscosity, diffusion, and thermal
conductivity
1 Introduction
The observed anticorrelation between oxygen and sodium
abundances in galactic globular clusters [1] requires for
its interpretation a precise knowledge of the production
and destruction reactions of oxygen and of the only stable sodium isotope, 23 Na. It is believed that these sites
bear the nucleosynthetic imprint of previous generations
a
[email protected]
of stars. This may involve the so-called hot bottom burning in stars on the asymptotic giant branch (AGB) of the
Hertzsprung-Russell diagram [2], as well as core hydrogen
burning in fast rotating massive stars during the main sequence [3].
In these stars, 23 Na may be produced in a hydrogen
burning region via the 22 Ne(p,γ)23 Na reaction, which is
included in the neon-sodium cycle (fig. 1). The impact of
22
Ne(p,γ)23 Na reaction rate uncertainties on the predicted
William I. Fine Theoretical Physics Institute
University of Minnesota
arXiv:1411.2952v1 [hep-ph] 11 Nov 2014
FTPI-MINN-14/39
UMN-TH-3410/14
November 2014
χc0 ω production in e+e− annihilation through ψ(4160).
Xin Lia and M.B. Voloshina,b,c
a
School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
b
William I. Fine Theoretical Physics Institute, University of Minnesota,
Minneapolis, MN 55455, USA
c
Institute of Theoretical and Experimental Physics, Moscow, 117218, Russia
Abstract
We argue that the recent BESIII data on the cross section for the process e+ e− →
χc0 ω in the center of mass energy range 4.21 - 4.42 GeV can be described by the
contribution of the known charmonium-like resonance ψ(4160) with the mass of about
4190 MeV. The value of the coupling in the transition ψ(4160) → χc0 ω needed for this
mechanism is comparable to that in another known similar transition χc0 (2P ) → J/ψ ω.
The suggested mechanism also naturally explains the reported relative small value of
the cross section for the final states χc1 ω and χc2 ω above their respective thresholds.
LEP3: a low-cost, high-luminosity Higgs factory
Michael Koratzinos1
Geneva
E-mail: [email protected]
The discovery of a relatively light Higgs opens up the possibility of circular e+e- Higgs factories.
LEP3 is such a machine with emphasis on low cost, since it re-uses most of the LHC
infrastructure, including the tunnel, cryogenics, and the two general-purpose LHC experiments
Atlas and CMS, with some modifications. The energy reach of LEP3 is 240GeV in the centre of
mass, close to the ZH production maximum. Alternative tunnel diameters and locations are
possible, including a Higgs factory housed in the UNK tunnel, UNK-L, and a machine located
in a new 80 km tunnel in the Geneva region, TLEP, than can further house a very high energy
pp collider. The design merits further consideration and a detailed study should be performed, so
that LEP3 can be one more option available to the community for the next step in High Energy
Physics.
LHC on the March - IHEP-LHC
20-22 November 2012
Institute for High Energy Physics, Protvino, Moscow region, Russia
1
Speaker
 Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
LEP3
http://pos.sissa.it
M. Koratzinos
1. Introduction
The recent discovery [1] [2] of the Higgs boson, the last missing link of the Standard
Model (SM), and the realization that it is rather light (with a mass of 125-126GeV) has renewed
the interest of circular e+e- colliders that can serve as a Higgs factories. Common wisdom that
any eventual Higgs factory would need to be a linear accelerator turns out not to be accurate.
Circular machines enjoy higher luminosities than those of a linear machine around the centre of
mass energy (ECM) needed for Higgs production via the Higgstrahlung process e+e-→ZH.
Moreover, compared to a linear machine, they have the advantage of multiple interaction points
and the technology they are based on is mature and carries little risk. The big disadvantage of
circular machines is the energy reach – a machine the size of LEP can only go to 250 GeV ECM,
within the maximum of the ZH process, but cannot reach 350GeV, where the couplings of the
Higgs to the top quark could also directly be measured. An 80 km machine can reach 350 GeV
ECM, but cannot go much higher than that. Whether the superior energy reach of linear machines
or the superior luminosity of circular machines is a decisive factor would critically depend on
the physics landscape after the first results of the 13-14 TeV run of the LHC are digested: If no
supersymmetric or other states are found, probably the superior performance of the circular
machines would be the decisive factor for the next large High Energy Physics project. If on the
other hand an exciting new state is found within the reach of a linear collider, linear colliders
would be the way forward. Today we simply do not know which type of machine will be best,
so all options merit a detailed study so that an informative decision can be taken at around 2018.
In this talk I will concentrate on the least expensive option of such a machine, LEP3 [3]
[4], in the LHC tunnel. Such an option enjoys an excellent cost to performance ratio as it will
re-use the whole of the LHC infrastructure (tunnel, cryogenics system, etc.) including the two
large general-purpose LHC experiments. Other tunnel diameters can (and should) also be
considered, and as it turns out performance increases linearly with the tunnel circumference.
2.The Higgs discovery
A new state has been discovered and the first indications are that it decays as expected for
a Standard Model Higgs [5] [6]. This discovery strongly influences the strategy for future
collider projects. After the initial verifications that the newly discovered particle is indeed
Standard Model-like, we are fast entering the precision measurement era: The new state needs
to be characterized, therefore we need to measure as accurately as possible the Higgs branching
ratios and related couplings, the Higgs coupling to the top quark, the Higgs quantum numbers,
the Higgs mass, the Higgs boson self couplings, its total decay width, etc; We need to verify the
(tree-level) structure of the theory: are there Invisible Higgs decays, Exotic decays, or any
deviations from SM through higher-order operators?; we need to evaluate (new physics) loopinduced effects; and finally, we might need to re-examine and measure even more precisely
EW parameters to over-constrain the theory.
We need to stress here that LHC discoveries at 13-14 TeV (operation expected to start in
2015) will lead to a broader horizon and will strongly influence the strategy for the future.
2
Determination of the θ23 octant in LBNO
C.R. Dasa,b,c,1 , Jukka Maalampia,2 , João Pulidob,3 and Sampsa Vihonena,4
arXiv:1411.2829v1 [hep-ph] 11 Nov 2014
a
Department of Physics, University of Jyväskylä
P.O. Box 35, FIN-40014 Jyväskylä, Finland
b
Centro de Física Teórica das Partículas (CFTP) Departamento de Física,
Instituto Superior Técnico Av. Rovisco Pais, P-1049-001 Lisboa, Portugal
c
Theoretical Physics Division, Physical Research Laboratory,
Navrangpura, Ahmedabad - 380 009, India
Abstract
According to the recent results of the neutrino oscillation experiment MINOS, the
neutrino mixing angle θ23 may not be maximal (45◦ ). Two nearly degenerate solutions
are possible, one in the lower octant (LO) where θ23 < 45◦ , and one in the higher
octant (HO) where θ23 > 45◦ . Long baseline experiments measuring the νµ → νe are
capable of resolving this degeneracy. In this work we study the potential of the planned
European LBNO experiment to distinguish between the LO and HO solutions.
PACS numbers: 14.60.Pq
Keywords: Neutrino oscillations, neutrino mixing, LBNO, long baseline
1
E-mail:
E-mail:
3
E-mail:
4
E-mail:
2
[email protected], [email protected]
[email protected]
[email protected]
[email protected]
CONSISTENCY TESTS OF ρ0 (770) − f0 (980) MIXING IN π − p → π − π + n
Miloslav Svec∗
Physics Department, Dawson College, Montreal, Quebec, Canada H3Z 1A4
(Dated: November 10, 2014)
arXiv:1411.2792v1 [hep-ph] 11 Nov 2014
Abstract
Analytical solutions of the S- and P -wave subsystem in π − p → π − π + n and π + n → π + π − p measured
on polarized targets at CERN reveal evidence for ρ0 (770) − f0 (980) spin mixing. We study the response
of these analytical solutions to the presence of small D wave amplitudes with helicity λ ≤ 1 (Response
analysis A) and λ ≤ 2 (Response analysis B) which contaminate the input data. In both Response analyses
the ρ0 (770) − f0 (980) spin mixing effect is clearly consistent with the presence of the D-wave amplitudes
provided they are not too large below 750 MeV. This result at low momentum transfer t is in agreement
with the evidence for ρ0 (770) − f0 (980) mixing in the presence of D-wave amplitudes from the amplitude
analysis of the CERN data on π − p → π − π + n at high t. We also show that the ρ0 (770) − f0 (980) mixing
is consistent with isospin relations for the S-wave intensities measured in π − p → π − π + n, π − p → π 0 π 0 n
and π + p → π + π + n processes. These results strengthen the experimental evidence for the ρ0 (770) − f0 (980)
spin mixing in π − p → π − π + n found in the analytical solutions and are in agreement with recent theoretical
expectations. We present a survey of moduli of the S-wave amplitudes and S-wave intensities from all
amplitude analyses of the five measurements of π − p → π − π + n and π + n → π + π − p on polarized targets.
All analyses are in a remarkable agreement that shows a clear evidence for a resonant structure at ρ0 (770)
mass in the S-wave moduli and intensities in a broad confirmation of the ρ0 (770) − f0 (980) spin mixing.
PACS numbers:
∗
electronic address: [email protected]
1
Preprint typeset in JHEP style - HYPER VERSION
DAMTP-2014-79
arXiv:1411.1663v1 [hep-ph] 6 Nov 2014
MFV Reductions of MSSM Parameter Space
S.S. AbdusSalam,a,b∗ C.P. Burgessc,d,e† and F. Quevedob,f ‡
a
b
c
d
e
f
INFN, Sez. di Roma, P.le A. Moro 2, I-00185 Roma, Italia
The Abdus Salam ICTP, Trieste, Italy
Department of Physics & Astronomy, McMaster University, Hamilton ON, Canada
Perimeter Institute for Theoretical Physics, Waterloo, ON, Canada
Division PH -TH, CERN, CH-1211, Gen`eve 23, Suisse
DAMTP, Cambridge University, Cambridge, UK
Abstract: The 100+ free parameters of the minimal supersymmetric standard model
(MSSM) make it computationally difficult to compare systematically with data, motivating
the study of specific parameter reductions such as the cMSSM and pMSSM. Here we instead
study the reductions of parameter space implied by using minimal flavour violation (MFV)
to organise the R-parity conserving MSSM, with a view towards systematically building in
constraints on flavour-violating physics. Within this framework the space of parameters is
reduced by expanding soft supersymmetry-breaking terms in powers of the Cabibbo angle,
leading to a 24-, 30- or 42-parameter framework (which we call MSSM-24, MSSM-30, and
MSSM-42 respectively), depending on the order kept in the expansion. We provide a
Bayesian global fit to data of the MSSM-30 parameter set to show that this is manageable
with current tools. We compare the MFV reductions to the 19-parameter pMSSM choice
and show that the pMSSM is not contained as a subset. The MSSM-30 analysis favours
a relatively lighter TeV-scale pseudoscalar Higgs boson and tan β ∼ 10 with multi-TeV
sparticles.
Keywords: Supersymmetry, Supersymmetric Standard Model, MSSM, Flavour
violation, LHC, Higgs mass, Bayesian.
∗
[email protected]
[email protected]
‡
[email protected]
†
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
arXiv:1411.2943v1 [hep-ex] 11 Nov 2014
CERN-PH-EP-2014-269
LHCb-PAPER-2014-050
11 November 2014
Measurement of Bc+ production in
proton-proton
collisions
√
at s = 8 TeV
The LHCb collaboration†
Abstract
Production of Bc+ mesons in proton-proton collisions at a center-of-mass energy of
8 TeV is studied with data corresponding to an integrated luminosity of 2.0 fb−1
recorded by the LHCb experiment. The ratio of production cross-sections times
branching fractions between the Bc+ → J/ψπ + and B + → J/ψK + decays is measured
as a function of transverse momentum and rapidity in the regions 0 < pT < 20 GeV/c
and 2.0 < y < 4.5. The ratio integrated within this kinematic range is measured
to be (0.683 ± 0.018 ± 0.009)%, where the first uncertainty is statistical and the
second systematic.
Submitted to Phys. Rev. Lett.
c CERN on behalf of the LHCb collaboration, licence CC-BY-4.0.
†
Authors are listed at the end of this Letter.
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)
arXiv:1411.2921v1 [hep-ex] 11 Nov 2014
CERN-PH-EP-2014-255
Submitted to: JHEP
Search for new phenomena in events with three or more charged
√
leptons in pp collisions at s = 8 TeV with the ATLAS detector
The ATLAS Collaboration
Abstract
A generic search for anomalous production of events with at least three charged leptons is pre√
sented. The data sample consists of pp collisions at s = 8 TeV collected in 2012 by the ATLAS experiment at the CERN Large Hadron Collider, and corresponds to an integrated luminosity of 20.3 fb−1 .
Events are required to have at least three selected lepton candidates, at least two of which must be
electrons or muons, while the third may be a hadronically decaying tau. Selected events are categorized based on their lepton flavour content and signal regions are constructed using several kinematic
variables of interest. No significant deviations from Standard Model predictions are observed. Modelindependent upper limits on contributions from beyond the Standard Model phenomena are provided
for each signal region, along with prescription to re-interpret the limits for any model. Constraints
are also placed on models predicting doubly charged Higgs bosons and excited leptons. For doubly
charged Higgs bosons decaying to eτ or µτ , lower limits on the mass are set at 400 GeV at 95%
confidence level. For excited leptons, constraints are provided as functions of both the mass of the
excited state and the compositeness scale Λ, with the strongest mass constraints arising in regions
where the mass equals Λ. In such scenarios, lower mass limits are set at 2.0 TeV for excited electrons
and muons, 1.8 TeV for excited taus, and 1.6 TeV for every excited-neutrino flavour.
c 2014 CERN for the benefit of the ATLAS Collaboration.
Reproduction of this article or parts of it is allowed as specified in the CC-BY-3.0 license.
Jet Multiplicity in Top-Quark Pair Events at CMS
arXiv:1411.2764v1 [hep-ex] 11 Nov 2014
A. Descroix for the CMS Collaboration
Karlsruhe Institut of Technologie, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
E-mail: [email protected]
Abstract. The normalised differential top quark-antiquark production cross section is
measured as a function of the jet multiplicity. Using a procedure to associate jets to decay
products of the top quarks, the differential cross section of the t¯t production is determined
as a function of the additional jet multiplicity. The fraction of events with no additional
jets is measured as a function of the threshold required for the transverse momentum of the
additional jet. The measurements are compared with predictions from perturbative quantum
chromodynamics and no significant deviations are observed.
1. Introduction
Top-pair events are often accompanied by additional hard jets that do not originate from
the decay of the top pair (t¯t+jets) at the LHC. These events provide an essential handle to
test higher-order QCD calculations of processes leading to multijet events but also to test the
choice of renormalisation and factorisation scales for data modeling. The correct description
of t¯t+jets production is crucial for the overall LHC physics program since it constitutes an
important background for processes of interest with multijet final states. Typical processes are
the associated Higgs-boson production with a t¯t pair, where the Higgs boson decays into jets,
or final states predicted in supersymmetric theories. Anomalous production of additional jets
accompanying a t¯t pair could be a sign of new physics beyond the standard model.
Using 5.0 fb−1 of proton-proton collisions at 7 TeV recorded in 2011 by the Compact Muon
Solenoid (CMS) detector, the t¯t cross section is measured differentially as a function of the
total number of jets in the event (in the dilepton and `+jets channels), and as a function of the
number of additional jets in the event (in the `+jets channel). The fraction of events that do
not contain additional jets (gap fraction), is determined as a function of the threshold on the
transverse momentum (pT ) of the leading additional jet (in the dilepton channel). A complete
documentation of this analysis and all the corresponding references can be found in [1].
2. Event Selection
Events in the dilepton channel are required to contain at least two isolated leptons (electrons
or muons) of opposite charge and at least two jets, of which at least one is identified as a bjet. A cut applied on events with a small lepton-pair invariant mass suppresses background
from heavy-flavour resonance decays. In the ee and µµ channels, the dilepton invariant mass
is required to be outside a Z-boson mass window, and a cut on the missing transverse energy
(MET) is applied. Finally a kinematic reconstruction method is used to identify the two b-jets
originating from the decay of the top quark and antiquark. Those events which do not provide
a valid reconstruction are rejected.
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-PH-EP/2014-261
2014/11/12
arXiv:1411.2646v1 [hep-ex] 10 Nov 2014
CMS-EXO-12-050
Search for quark contact interactions and extra spatial
dimensions using dijet angular √
distributions in
proton-proton collisions at s = 8 TeV
The CMS Collaboration∗
Abstract
A search is presented for quark
√ contact interactions and extra spatial dimensions in
proton-proton collisions at s = 8 TeV using dijet angular distributions. The search
is based on a data set corresponding to an integrated luminosity of 19.7 fb−1 collected
by the CMS detector at the CERN LHC. Dijet angular distributions are found to be
in agreement with the perturbative QCD predictions that include electroweak corrections. Limits on the contact interaction scale from a variety of models at next-toleading order in QCD corrections are obtained. A benchmark model in which only
left-handed quarks participate is excluded up to a scale of 9.0 (11.7) TeV for destructive (constructive) interference at 95% confidence level. Lower limits between 6.0 and
8.4 TeV on the scale of virtual graviton exchange are extracted for the Arkani-Hamed–
Dimopoulos–Dvali model of extra spatial dimensions.
Submitted to Physics Letters B
c 2014 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license
∗ See
Appendix B for the list of collaboration members
Can neutrino mass be measured in low-energy electron capture
decay?
R. G. H. Robertson∗
Department of Physics
arXiv:1411.2906v1 [nucl-th] 11 Nov 2014
and Center for Experimental Nuclear Physics and Astrophysics,
University of Washington, Seattle, WA 98195
(Dated: November 12, 2014)
Abstract
The standard kinematic method for determining neutrino mass from the beta decay of tritium
or other isotope is to measure the shape of the electron spectrum near the endpoint. It has been
known for 30 years that a similar distortion of the “visible energy” remaining after electron capture
is caused by neutrino mass. There has been a resurgence of interest in using this method with 163 Ho.
Recent theoretical analyses offer reassurance that there are no significant theoretical uncertainties.
We show that the situation is, however, more complicated, and that the spectrum shape is presently
not well enough understood to permit a sensitive determination of the neutrino mass in this way.
1
RBRC-1099
Axial current generation by P-odd domains in QCD matter
Ioannis Iatrakis,1, ∗ Shu Lin,2, † and Yi Yin3, 4, ‡
arXiv:1411.2863v1 [hep-th] 11 Nov 2014
1
Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
2
RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
3
Physics Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
4
Physics Department, University of Illinois at Chicago, Chicago, Illinois 60607-7059, USA
(Dated: November 12, 2014)
The dynamics of topological domains which break parity(P) and charge-parity (CP) symmetry
of QCD are studied. We derive in a general setting that those local domains will generate an
axial current and quantify the strength of the induced axial current. Our findings are verified in a
top-down holographic model. The relation between the real time dynamics of those local domains
and chiral magnetic effect is also elucidated. We finally argue that such an induced axial current
would be phenomenologically important if topological domains are created in heavy-ion collisions
experiment.
PACS numbers: 72.10.Bg, 03.65.Vf, 12.38.Mh
Introduction.—One remarkable and intriguing feature
of non-Abelian gauge theories such as the gluonic sector of quantum chromodynamics (QCD) is the existence
of topologically non-trivial configurations of gauge fields.
These configurations are associated with tunneling between different states which are Rcharacterized by a topological winding number: QW = d4 x q, where the topological charge q = g 2 µνρσ tr (Gµν Gρσ ) /(32π 2 ) with Gµν
the color field strength. While the amplitudes of transition between those topological states are exponentially
suppressed at zero temperature, such exponential suppression might disappear at high temperature or high
density[1]. In particular, for hot QCD matter created
in the high energy heavy-ion collisions, there could be
metastable domains occupied by such a topological gauge
field configuration which violates parity(P) and chargeparity (CP) locally. We will refer to those topological
domains as “θ domain” in this letter.
Due to its deep connection to the fundamental aspect
of QCD, namely the nature of P and CP violation, with
far-reaching impacts on other branches of physics, in particular cosmology, the search of possible manifestation of
those “θ domains” in heavy-ion collisions has attracted
much interest recently[2, 3]. A “θ domain” will generate
chiral charge imbalance through axial anomaly relation:
µ
∂µ JA
= −2q .
(1)
Furthermore, the intriguing interplay between U(1) triangle anomaly(in electro-magnetic sector) and chiral
charge imbalance would lead to novel P and CP odd
effects which provide promising mechanisms for the experimental detection of “θ domains”. For example, a
vector current and consequently the vector charge separation will be induced in the presence of a magnetic field
and chiral charge imbalance. Such an effect is referred
as the chiral magnetic effect(CME) [4] (see Ref. [5] for
a recent review). In terms of chiral charge imbalance
parametrized by the axial chemical potential µA , CME
current is given by: jV = (Nc eBµA )/(2π 2 ).
To decipher the nature of “θ domain” through vector charge separation effects such as CME, it is essential to understand not only the distribution of those chiral charge imbalance, but their dynamical evolution as
well. Previously, most studies were based on introducing chiral asymmetry by hand, after which the equilibrium response to a magnetic field(or vorticity) is investigated (see Ref. [6] for the case in which the chirality
is generated dynamically due to a particular color flux
tube configuration). In reality, such as in heavy-ion collisions experiment, however, the chiral imbalance is dynamically generated through the presence of “θ domain”.
In this letter, we study the axial current induced by dynamics of “θ domain”, which can be conveniently described by introducing a space-time dependent θ angle
θ(t, x)(c.f. Refs. [2, 7]). One may interpret θ(t, x) as an
effective axion field creating a “θ domain”. We show
that the presence of θ(t, x) will not only generate chiral charge imbalance, it will also lead to an axial current(c.f. Fig. 1):
jA = −κCS ∇θ(t, x) .
(2)
Such an axial current, which has not been considered
in literature so far, should be present in systems where
“θ domains” are generated dynamically. Our results are
valid as far as the variation of θ(t, x) in space is on the
scale larger than 1/T (or mean free path of the system)
and the variation of θ(t, x) in time is on scale longer
than the relaxation time of the system but shorter than
the life time of “θ domain”. It is therefore independent
of the microscopic details of the system. While we are
considering a system which is in the deconfined phase
of QCD, the resulting current bears a close resemblance
to that in the superfluid. One may interpret the gradient ∇θ(t, x) in Eq. (2) as the “velocity” of “θ domain”,
similar to the case of superfluid that the gradient of the
phase of the condensate is related to the superfluid ve-
c ESO 2014
Astronomy & Astrophysics manuscript no. twin˙db˙sb
November 12, 2014
A new quark-hadron hybrid equation of state for astrophysics
I. High-mass twin compact stars
Sanjin Beni´c1,2 ⋆ , David Blaschke3,4
1
2
arXiv:1411.2856v1 [astro-ph.HE] 11 Nov 2014
3
4
5
6
⋆⋆ ,
David E. Alvarez-Castillo4,5
⋆⋆⋆ ,
Tobias Fischer3 † , and Stefan Typel6
‡
Physics Department, Faculty of Science, University of Zagreb, Bijeniˇcka c. 32, Zagreb 10000, Croatia
Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Institute for Theoretical Physics, University of Wrocław, Pl. M. Borna 9, 50-204 Wroclaw, Poland
Bogoliubov Laboratory for Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia
Instituto de F´ısica, Universidad Aut´onoma de San Luis Potos´ı, S.L.P. 78290, M´exico
GSI Helmholtzzentrum f¨ur Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt, Germany
Received: day month year; accepted: day month year
ABSTRACT
Aims. We present a new microscopic hadron-quark hybrid equation of state model for astrophysical applications, from which compact
hybrid star configurations are constructed. These are composed of a quark core and a hadronic shell with first-order phase transition
at their interface. The resulting mass-radius relations are in accordance with the latest astrophysical constraints.
Methods. The quark matter description is based on a QCD motivated chiral approach with higher-order quark interactions in the Dirac
scalar and vector coupling channels. For hadronic matter we select a relativistic mean-field equation of state with density-dependent
couplings. Since the nucleons are treated in the quasi-particle framework, an excluded volume correction has been included for the
nuclear equation of state at suprasaturation density which takes into account the finite size of the nucleons.
Results. These novel aspects, excluded volume in the hadronic phase and the higher-order repulsive interactions in the quark phase,
lead to a strong first-order phase transition with large latent heat, i.e. the energy-density jump at the phase transition, which fulfills
a criterion for a disconnected third-family branch of compact stars in the mass-radius relationship. These twin stars appear at high
masses (∼ 2 M⊙ ) being relevant for current observations of high-mass pulsars.
Conclusions. This analysis offers a unique possibility by radius observations of compact stars to probe the QCD phase diagram at
zero temperature and large chemical potential and even to support the existence of a critical point in the QCD phase diagram.
Key words. stars: neutron – stars: interiors – dense matter – equation of state
1. Introduction
The physics of compact stars is an active subject of modern nuclear astrophysics research since it allows to probe the state of
matter at conditions which are currently inaccessible in highenergy collider facilities: extremes of baryon density at low
temperature. It provides one of the strongest observational constraints on the zero-temperature equation of state (EoS) by recent high-precision mass measurement of high-mass pulsars by
Demorest et al. (2010) and Antoniadis et al. (2013). Any scenarios for the existence of exotic matter and a phase transition at
high density which tend to soften the EoS may be abandoned unless they provide stable compact star configurations with a mass
not less than 2 M⊙ . Still, there are several possibilities for which
it is hard or impossible to detect quark matter in compact stars,
namely when: a) the phase transition occurs at too high densities,
exceeding the central density of the maximum mass configuration, b) the transition occurs only very close to the maximum
mass, beyond the limit of masses for observed high-mass pulsars, or when c) the transition is a crossover or very close to it so
that the hybrid star characteristics is indistinguishable from that
⋆
⋆⋆
⋆⋆⋆
†
‡
e-mail: [email protected]
e-mail: [email protected]
e-mail: [email protected]
e-mail: [email protected]
e-mail: [email protected]
of pure neutron stars. The latter case has been dubbed “masquerade” problem Alford et al. (2005). The latter case seems
to be characteristic to the use of modern chiral quark models
with vector meson interactions Bratovic et al. (2013) which are
very similar in their behaviour to standard nuclear EoS like APR
(Akmal, Pandharipande & Ravenhall , 1998) or DBHF (Fuchs ,
2006) in the transition region (see, e.g., Kl¨ahn et al. (2007),
Kl¨ahn et al. (2013)). However, the opposite case is also possible: when the phase transition to quark matter is accompanied
with a large enough binding energy release, corresponding to a
jump in density and thus a compactification of the star, an instability may be triggered which eventually will result in the
emergence of a third family of compact stellar objects, in addition of white dwarfs and neutron stars. About the existence of
such a branch of supercompact stellar objects which is disconnected from the neutron star sequence has long been speculated
in different context related to phase transitions in dense matter (c.f. Gerlach , 1968; K¨ampfer , 1981; Schertler et al. , 2000;
Glendenning & Kettner , 2000). This phenomenon has been
studied due to the appearance of pion and kaon condensates in
K¨ampfer (1981) and Banik & Bandyopadhyay (2001) respectively, as well as hyperons in Schaffner-Bielich et al. (2002) and
quark matter in Glendenning & Kettner (2000), Schertler et al.
(2000), Fraga et al. (2002), Banik & Bandyopadhyay (2003),
Agrawal & Dhiman (2009), and Agrawal (2010). All these
early studies, however, could be ruled out by the recent observa-
1
A scenario for inflationary magnetogenesis without strong coupling problem
Gianmassimo Tasinato
Department of Physics, Swansea University, Swansea, SA2 8PP, UK and
arXiv:1411.2803v1 [hep-th] 11 Nov 2014
Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX, UK
Cosmological magnetic fields pervade the entire universe, from small to large scales. Since
they apparently extend into the intergalactic medium, it is tantalizing to believe that they
have a primordial origin, possibly being produced during inflation. However, finding consistent scenarios for inflationary magnetogenesis is a challenging theoretical problem. The
requirements to avoid an excessive production of electromagnetic energy, and to avoid entering a strong coupling regime characterized by large values for the electromagnetic coupling
constant, typically allow one to generate only a tiny amplitude of magnetic field during
inflation. We propose a scenario for building gauge-invariant models of inflationary magnetogenesis potentially free from these issues. The idea is to derivatively couple a dynamical
scalar, not necessarily the inflaton, to fermionic and electromagnetic fields during the inflationary era. Such couplings give additional freedom to control the time-dependence of the
electromagnetic coupling constant during inflation. This fact allows us to find conditions
to avoid the strong coupling problems that affect many of the existing models of magnetogenesis. We do not need to rely on a particular inflationary set-up for developing our
scenario, that might be applied to different realizations of inflation. On the other hand,
specific requirements have to be imposed on the dynamics of the scalar derivatively coupled
to fermions and electromagnetism, that we are able to satisfy in an explicit realization of
our proposal.
I.
INTRODUCTION
Cosmological magnetic fields seem to pervade the entire universe, from large to small scales. The
existence of magnetic fields at intergalactic distances has been inferred by the lack of GeV γ−rays
detection from blazars, astrophysical objects that are known to produce photons with energies in
the TeV range. Interactions with the intergalactic medium should convert at least part of these
high energy TeV γ−rays into lower energy secondary charged particles, which then should decay
into GeV photons. The latter are however not detected, and the simplest explanation for this
fact is the presence of an intergalactic magnetic field, that deflects the secondary charged particles
[1]. The required amplitude for such magnetic field is found in [2] to be at least 10−15 Gauss. In
addition, magnetic fields are also measured within galaxies. They are thought to be amplified by
dynamo effects starting from a seed magnetic field, that should have an amplitude of at least 10−20
Gauss to render the dynamo mechanism efficient. See [3] for a recent review.
Generating cosmological magnetic fields of such strengths is a challenging theoretical problem.
Since they seem to pervade the intergalactic medium, it is tantalizing to believe that they have a
primordial origin, possibly being produced during inflation. On the other hand, Maxwell theory
of electromagnetism is conformally invariant. This implies that it does not lead by itself to the
production of a coherent background of electromagnetic modes in a Friedmann-Robertson-Walker
cosmology, since the latter can be expressed in conformally flat coordinates. To generate a sizeable
magnetic field during inflation, the conformal invariance of Maxwell action has to be broken. The
first attempts in this direction have been push forward by Turner and Widrow in [4], by coupling
Maxwell electromagnetism to space-time curvature. However, the most promising models in their
set-up are plagued by ghosts [5, 6], and are therefore inconsistent. Another interesting scenario has
been proposed by Ratra [7] by kinetically coupling the inflaton scalar field to electromagnetism,
Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions
Wei-Tian Deng1 and Xu-Guang Huang2
arXiv:1411.2733v1 [nucl-th] 11 Nov 2014
2
1
School of physics, Huazhong University of Science and Technology, Wuhan 430074, China
Physics Department and Center for Particle Physics and Field Theory, Fudan University, Shanghai 200433, China.
(Dated: November 12, 2014)
The non-central Cu + Au collisions can create strong out-of-plane magnetic fields and in-plane electric fields.
By using the HIJING model, we study the general properties of the electromagnetic fields in Cu + Au collisions
at 200 GeV and their impacts on the charge-dependent two-particle correlator γq1 q2 = hcos(φ1 + φ2 − 2ψRP )i
(see main text for definition) which was used for the detection of the chiral magnetic effect (CME). Compared
with Au + Au collisions, we find that the in-plane electric fields in Cu + Au collisions can strongly suppress
the two-particle correlator or even reverse its sign if the lifetime of the electric fields is long. Combining with
the expectation that if γq1 q2 is induced by elliptic-flow driven effects we would not see such strong suppression
or reversion, our results suggest to use Cu + Au collisions to test CME and understand the mechanisms that
underlie γq1 q2 .
PACS numbers: 25.75.Ag, 24.10.Jv, 24.10.Lx
I.
INTRODUCTION
Over the past few years, there has been increasing interest in the quantum-anomaly-related transport phenomena and their experimental signals in heavy-ion collisions.
Such anomalous transports include chiral magnetic effect
(CME) [1–3], chiral vortical effect (CVE) [4–6], chiral separation effect (CSE) [7, 8], chiral electric separation effect
(CESE) [9, 10], etc. All these effects involve a net chiral
imbalance in the quark-gluon plasma (QGP) and their occurrence, if confirmed, provides us hitherto unique evidence
for the local P and CP violation in QGP. For review on the
anomalous transports in heavy-ion collisions, see for example
Refs [11–13].
The CME in QGP can be neatly expressed as
J = σ5 B with σ5 = Nc
X q2f µ5
f
2π2
,
(1)
where the summation is over all light quark flavors, Nc is the
number of colors, µ5 is the chiral chemical potential, q f is
the electric charge of quark flavor f , and B is a magnetic
field. Equation (1) represents an electric current induced by
a magnetic field in QGP with net chirality (characterized by
µ5 ). In real heavy-ion collisions, the magnetic fields are generated mostly in the direction perpendicular to the reaction
plane (For discussions about the event-by-event fluctuation of
the magnetic field orientation, see Refs. [14]), therefore the
CME is expected to induce a charge separation with respect
to the reaction plane which may be detected, as proposed by
Voloshin [15], via the two-particle correlator
γq1 q2 = hcos(φ1 + φ2 − 2ψRP )i,
(2)
where q1 and q2 are charges of particles 1 and 2, φ1 , φ2 ,
and ψRP are the azimuthal angles for the particles 1, 2, and
the reaction plane, respectively, and the average in Eq. (2)
is taken over events. Negative same-sign (SS) correlator
γSS ≡ (γ++ + γ−− )/2 and positive opposite-sign (OS) correlator γOS ≡ γ+− could constitute a strong evidence for the
occurrence of CME. The measurements have been carried out
by STAR Collaboration [16–19] at RHIC for Au + Au and
Cu + Cu collisions and ALICE Collaboration [20] at LHC for
Pb + Pb collisions. The experimental results of γq1 q2 showed
consistent behavior with the expectation of CME. However,
there still remain debates [21–26] on the CME interpretation
of the data because γq1 q2 may have contributions from other
effects, potentially the elliptic-flow (v2 ) driven ones, e.g., the
transverse momentum conservation (TMC) [23, 25] and local
charge conservation (LCC) [26]. (If one measures the difference between the SS and OS correlators, the TMC contribution can be subtracted as it is charge independent, but the LCC
remains to contribute.) It was proposed [27] to use the central
U + U collisions which are expected to have sizable elliptic
flows but no magnetic fields to disentangle the CME and v2
driven contributions. Preliminary results for γq1 q2 in U + U
collisions have been reported by STAR collaboration [18], but
there are still uncertainties, see discussions in Ref. [28].
The purpose of this paper is to propose to use another colliding system, that is, the Cu + Au collisions at RHIC to test
CME-induced and the v2 -driven contributions to γq1 q2 . The
idea is the following. If γq1 q2 is dominated by v2 -driven effects, we expect that γq1 q2 (more precisely, ∆γ ≡ γOS − γSS ,
because the directed flow in Cu + Au collisions may contribute
to both γOS and γSS . This contribution does not exist in Au +
Au collisions.) would not change too much from Au + Au
collisions to Cu + Au collisions. (A plausible guess would be
that ∆γ as a function of centrality in Cu + Au collisions lie between that in Cu + Cu and Au + Au collisions). However, on
the other hand, if γq1 q2 is driven by CME, then the correlator
in Cu + Au collisions will be very different from that in Au
+ Au collisions. This is because that, in noncentral Cu + Au
collisions, due to the asymmetric collision geometry, there can
generate electric fields pointing from Au to Cu nuclei which
can induce an in-plane charge separation in addition to the
out-of-plane charge separation due to CME. Thus the resulting
charge dipolar distribution will deviate from the out-of-plane
direction, and as a consequence, both the SS and OS correlators will descend, see Fig. 1 for an illustration. If the in-plane
electric fields are so strong (or somehow equivalently, if their
Cosmological Implications of Light Sterile Neutrinos produced
after the QCD Phase Transition
arXiv:1411.2690v1 [astro-ph.CO] 11 Nov 2014
Louis Lello1, ∗ and Daniel Boyanovsky1 , †
1
Department of Physics and Astronomy,
University of Pittsburgh, Pittsburgh, PA 15260, USA
(Dated: November 12, 2014)
Abstract
We study the production of sterile neutrinos in the early universe from π → lνs shortly after
the QCD phase transition in the absence of a lepton asymmetry while including finite temperature
corrections to the π mass and decay constant fπ . Sterile neutrinos with masses . 1M eV produced
via this mechanism freeze-out at Tf ≃ 10M eV with a distribution function that is highly nonthermal and features a sharp enhancement at low momentum thereby making this species cold
even for very light masses. Dark matter abundance constraints from the CMB and phase space
density constraints from the most dark matter dominated dwarf spheroidal galaxies provide upper
and lower bounds respectively on combinations of mass and mixing angles. For π → µνs , the
bounds lead to a narrow region of compatibility with the latest results from the 3.55KeV line. The
non-thermal distribution function leads to free-streaming lengths (today) in the range of ∼ few kpc
consistent with the observation of cores in dwarf galaxies. For sterile neutrinos with mass . 1eV
that are produced by this reaction, the most recent accelerator and astrophysical bounds on Uls
combined with the non-thermal distribution function suggests a substantial contribution from these
sterile neutrinos to Nef f .
PACS numbers: 95.35.+d,95.30.Cq,13.15.+g
∗
†
Electronic address: [email protected]
Electronic address: [email protected]
1
arXiv:1411.2658v1 [hep-th] 10 Nov 2014
Anatomy of new SUSY breaking
holographic RG flows
Riccardo Argurio∗1 , Daniele Musso†2 , and Diego Redigolo‡1,3,4
1 Physique
Th´eorique et Math´ematique and International Solvay Institutes, Universit´e Libre de
Bruxelles, C.P. 231, 1050 Brussels, Belgium
2 International Center of Theoretical Physics (ICTP), Strada Costiera 11, I 34014 Trieste, Italy
3 Sorbonne Universit´
es, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris, France
4 CNRS, UMR 7589, LPTHE, F-75005, Paris, France
Abstract
We find and thoroughly study new supergravity domain wall solutions which are
holographic realizations of supersymmetry breaking strongly coupled gauge theories.
We set ourselves in an N = 2 gauged supergravity with a minimal content in
order to reproduce a dual N = 1 effective SCFT which has a U (1)R symmetry, a
chiral operator whose components are responsible for triggering the RG flow, and
an additional U (1)F symmetry. We present a full three dimensional parameter
space of solutions, which generically break supersymmetry. Some known solutions
are recovered for specific sets of values of the parameters, with the new solutions
interpolating between them. The generic backgrounds being singular, we provide a
stability test of their dual theories by showing that there are no tachyonic resonances
in the two point correlators. We compute the latter by holographic renormalization.
We also carefully analyze the appearance of massless modes, such as the dilaton and
the R axion, when the respective symmetries are spontaneously broken, and their
lifting when the breaking is explicit. We further comment on the application of
such class of backgrounds as archetypes of strongly coupled hidden sectors for gauge
mediation of supersymmetry breaking. In particular, we show that it is possible to
model in this way all types of hierarchies between the visible sector gaugino and
sfermion masses.
∗
[email protected]
[email protected]
‡
[email protected]
†
On Functional Representations of the Conformal Algebra
Oliver J. Rosten∗
Unaffiliated
Abstract
arXiv:1411.2603v1 [hep-th] 10 Nov 2014
Starting with conformally covariant correlation functions, a sequence of functional representations of the conformal algebra is constructed. A key step is the introduction of representations
which involve an auxiliary functional. It is observed that these functionals are not arbitrary but
rather must satisfy a pair of consistency equations; one such is identified, in a particular representation, as an Exact Renormalization Group equation specialized to a fixed-point. Therefore, the
associated functional is identified with the Wilsonian Effective Action and this creates a concrete
link between action-free formulations of Conformal Field Theory and the cutoff-regularized path
integral approach.
Following this, the energy-momentum tensor is investigated, from which it becomes apparent that
the conformal Ward Identities serve to define a particular representation of the energy-momentum
tensor. It follows, essentially trivially, that if the Schwinger functional exists and is non-vanishing
then theories exhibiting invariance under translations, rotations and dilatations enjoy full conformal
symmetry. In the Wilsonian approach, the exactly marginal, redundant field which generates lines
of physically equivalent fixed-points is identified as the trace of the energy-momentum tensor.
In loving memory of Francis A. Dolan.
∗
[email protected]
1
arXiv:1411.2255v1 [quant-ph] 9 Nov 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
Influence of the measurement on the decay law: the bang-bang
case
Francesco Giacosa1,2 and Giuseppe Pagliara3
1
Institute of Physics, Jan Kochanowski University, 25-406 Kielce, Poland
Institute for Theoretical Physics, J. W. Goethe University,
Max-von-Laue-Str. 1, D–60438 Frankfurt am Main,Germany
3
Dip. di Fisica e Scienze della Terra dell’Università di Ferrara and
INFN Sez. di Ferrara, Via Saragat 1, I-44100 Ferrara, Italy
2
Abstract. After reviewing the description of an unstable state in the framework of nonrelativistic Quantum Mechanics (QM) and relativistic Quantum Field Theory (QFT), we
consider the effect of pulsed, ideal measurements repeated at equal time intervals on the
lifetime of an unstable system. In particular, we investigate the case in which the ‘bare’
survival probability is an exact exponential (a very good approximation in both QM and
QFT), but the measurement apparatus can detect the decay products only in a certain
energy range. We show that the Quantum Zeno Effect can occur in this framework as
well.
1 Introduction
The study of decays is important in atomic, nuclear, and particle physics. Quite remarkably, although
weak decays of nuclei (e.g. double-β decays with lifetime ∼ 1021 y), and fast decays of hadrons
(with lifetime ∼ 10−22 sec) are characterized by very different decay times, the basic phenomenon is
the same: a coupling of an initial unstable state to a continuum of final states, which results in an
irreversible quantum transition (infinite Poincare’ time).
It is now well established both in Quantum Mechanics (QM) [1–3] and in Quantum Field Theory
(QFT) [4, 5] that the survival probability p(t) of an unstable state |S i is never exactly an exponential
function: deviations at short as well as at long times take place. In the context of QM, these deviations
have been verified experimentally at short-times in Ref. [6] and at long times in Ref. [7]. In particular,
at short times the behavior p(t) ≃ 1 − t2 /τ2Z occurs. In turn, the so-called Quantum Zeno Effect
(QZE) takes place if repeated ideal measurements at time intervals τ . τZ are performed (bang-bang
measurements) [8–12]. The non-decay probability after N measurements (i.e. at the time t = Nτ) is
then given by


 t2 
N
2 2 N

p(τ) ≃ 1 − t /τZ ≃ exp − 2  → 1 for N → ∞ (i.e. τ → 0, t fixed).
(1)
NτZ
Experimentally, the QZE was observed by inhibition of a Rabi oscillation between atomic energy
levels in Ref. [13, 14] and, for a genuine unstable quantum state (tunneling), in Ref. [15].
A covariantly foliated higher dimensional space-time: Implications for
short distance gravity and BSM physics
arXiv:1407.8493v2 [hep-th] 10 Nov 2014
Cao H. Nam∗
Institute of Physics, Vietnam Academy of Science and Technology,
10 Dao Tan, Ba Dinh, Hanoi, Vietnam
(Dated: November 11, 2014)
Abstract
We consider the space-time at short distances in which it is described by a D-dimensional manifold
(bulk) carrying out the principal bundle structure. As a result, this space-time manifold is foliated in the
covariant way by the (D − 4)-dimensional submanifolds, realized as the space-like internal spaces, that are
smooth copies of the Lie group G considered in this paper as the special unitary group. The submanifolds
being transversal to the internal spaces are realized as the external spaces and in fact identified as the
usual 4-dimensional world. The fundamental degrees of freedom determining the geometrical dynamics
of the bulk corresponding with short distance gravity are given by the gauge fields, the external metric
field and the modulus fields setting dynamically the volume of the internal spaces. These gauge fields
laying the bulk is to point precisely out the local directions of the external spaces which depend on the
topological non-triviality of the space-time principal bundle. The physical size of the internal spaces is
fixed dynamically by the moduli stabilization potential which completely arise from the intrinsic geometry
of the bulk. A detail description of the low energy bulk gravity in the weak field limit is given around
the classical ground state of the bulk. Additionally, we investigate the dynamics of the fundamentally
4-dimensional Weyl spinor fields and the fields of carrying out the non-trivial representations of the Lie
group G propagating in the bulk in a detail study. These results suggest naturally the possible solutions
to some the experimental problems of Standard Model, the smallness of the observed neutrino masses and
a dark matter candidate.
PACS numbers: 04.50.-h, 02.40.-k, 04.60.-m, 11.25.Mj
∗
Electronic address: [email protected]
1
TTP14-013
(Quasi-)Degeneration, Quantum Corrections and Neutrino Mixing∗
W. G. Hollik†
Institut für Theoretische Teilchenphysik (TTP), Karlsruhe Institute for Technology
In the case of neutrinos having significant masses to be measured in direct search, there are sizeable
corrections to the PMNS matrix. We show the universality of loop effects from any new physics sector
and discuss the seesaw-extended MSSM as an example of a non-minimal flavour violating theory with
non-decoupling effects.
arXiv:1411.2946v1 [hep-ph] 11 Nov 2014
I.
INTRODUCTION
In the Standard Model of elementary particle physics, neutrinos play a special role among the fermions: neutrinos are
exactly massless and neutrinos only appear as left-handed fermions. On the one hand, oscillation experiments suggest
non-vanishing neutrino masses [1, 2] which at least have to be in the sub-eV regime. On the other hand, masses of
righthanded neutrinos are unconstrained by the symmetries of the Standard Model and can in principle be much larger
than the electroweak scale [3].
a. Neutrino masses and quasi-degeneration The absolute mass scale of the light neutrinos, however, is still unknown.
Global fits on neutrino data give very precise measurements of the mass squared differences ∆m2i j = m2i − m2j [4] (similar
results are obtained by other groups [5, 6]):
−5
∆m221 = 7.54+0.26
eV2 ,
−0.22 × 10
(I.1)
∆m231 = 2.45 ± 0.06 × 10−3 eV2 .
Unknown as well is the hierarchy of the spectrum: the sign of the larger ∆m231 is yet undetermined and distinguishes
between normal (1-2-3) or inverted (3-1-2) hierarchy.
If the lightest neutrino is sufficiently heavy, direct mass searches as done by the Karlsruhe Tritium Neutrino Experiment
(KATRIN) [7] or will be able to measure it—or set a tight upper bound on the effective electron neutrino mass m2ν =
e
P 2 2
U m . After three years of measurement a sensitivity m ≤ 0.2 eV is expected [8].
νe
ei
i
i
b. Quark vs. lepton mixing In the quark sector, flavour mixing is encoded in the Cabibbo-Kobayashi-Maskawa (CKM)
matrix [9, 10] whose mixing angles are measured to be small leading to a CKM matrix being closely the unit matrix. On
the other hand, neutrino mixing is encoded in the leptonic mixing matrix according to Pontecorvo [11], Maki, Nakagawa
and Sakata [12] (PMNS) which is strongly non-hierarchical and shows rather arbitrary mixing. A schematical comparison
between both is shown in Fig. 1.
The small mixings of the quark sector suggest to generate them as an effect of quantum corrections, where the mixing
pattern of the PMNS matrix is usually addressed by postulating flavour symmetries. However, the possibility of radiative
generation of neutrino mixing becomes important in a regime where neutrino masses are quasi-degenerate which will be
proven by the direct mass searches.

② q ♣


q ② ♣ ,
VCKM = 


♣
♣
②


✇ t

t ✉
UPMNS = 

q ✉

q

✉ 

✇
Figure 1: Sizes of the mixing matrix elements—CKM versus PMNS mixing.
Talk given at the 42th ITEP winter school (Feb 11–18 2014), Otradnoe, Moscow, Russia.
Electronic address: [email protected]
∗
†
Perturbative growth of high-multiplicity W, Z and Higgs
production processes at high energies
arXiv:1411.2925v1 [hep-ph] 11 Nov 2014
Valentin V. Khoze∗
Institute for Particle Physics Phenomenology, Department of Physics
Durham University, Durham DH1 3LE, United Kingdom
Abstract
Using the classical recursion relations we compute scattering amplitudes in a spontaneously
broken Gauge–Higgs theory into final states involving high multiplicities of massive vector
bosons and Higgs bosons. These amplitudes are computed in the kinematic regime where
the number of external particles n is 1 and their momenta are non-relativistic. Our
results generalise the previously known expressions for the amplitudes on the multi-particle
thresholds to a more non-trivial kinematic domain. We find that the amplitudes in spontaneously broken gauge theories grow factorially with the numbers of particles produced, and
that this factorial growth is only mildly affected by the energy-dependent formfactor computed in the non-relativistic limit. This is reminiscent of the behaviour previously found in
massive scalar theories. Cross sections are obtained by integrating the amplitudes squared
over the non-relativistic phase-space and found to grow exponentially at energy scales in a
few hundred TeV range if we use the non-relativistic high multiplicity limit. This signals
a breakdown of perturbation theory and indicates that the weak sector of the Standard
Model becomes effectively strongly coupled at these multiplicities. There are interesting
implications for the next generation of hadron colliders both for searches of new physics
phenomena beyond and within the Standard Model.
∗
[email protected]
arXiv:1411.2922v1 [hep-ph] 11 Nov 2014
Dark Matter and Lepton Flavour Violation
in a Hybrid Neutrino Mass Model
Frank Deppisch1 , Wei-Chih Huang2
Department of Physics and Astronomy, University College London, UK
Abstract
We describe a hybrid model in which the light neutrino mass matrix receives both treelevel seesaw and loop-induced contributions. An additional U (1) gauge symmetry is used to
stabilize the lightest right-handed neutrino as the Dark Matter candidate. After fitting the
experimental neutrino data, we analyze and correlate the phenomenological consequences of
the model, namely its impact on electroweak precision measurements, the Dark Matter relic
abundance, lepton flavour violating rare decays and neutrinoless double beta decay. We find
that natural realizations of the model characterized by large Yukawa couplings are compatible
with and close to the current experimental limits.
1
2
[email protected]
[email protected]
Investigation of Neutralino Pair Production in Photon-Photon
Collider at ILC
Nasuf SONMEZ
Ege University, Physics Department, Izmir, Turkey∗
arXiv:1411.2920v1 [hep-ph] 11 Nov 2014
(Dated: November 12, 2014)
Abstract
Neutralino pair production via photon-photon collisions is analyzed in the context of Minimal
Supersymmetric Standard Model at future linear collider. Since photon does not have self coupling,
this process is only possible at Next-to-Leading order and all the possible terms are calculated for
the photon-photon interaction, including box, triangles and quartic coupling diagrams. Numerical
analysis of the production rates for χ
˜01 χ
˜01 , χ
˜01 χ
˜02 and χ
˜02 χ
˜02 are presented for four new distinct benchmark models which are presented in the light of LHC8. Angular dependence of each neutralino
pairs for the benchmark points are also presented. Total integrated photonic cross section goes up
to 1.23 f b and 1.26 f b for the χ
˜01 χ
˜01 and χ
˜02 χ
˜02 pairs, respectively for the Radiatively driven natural
susy benchmark point.
∗
[email protected]
1
Fermion mass and mixing hierarchy in an SU(5) grand unified model with extra
flavour symmetries.
A. E. C´
arcamo Hern´andez,1, ∗ Sergey Kovalenko,1, † and Iv´an Schmidt1, ‡
arXiv:1411.2913v1 [hep-ph] 11 Nov 2014
1
Universidad T´ecnica Federico Santa Mar´ıa and Centro Cient´ıfico-Tecnol´
ogico de Valpara´ıso
Casilla 110-V, Valpara´ıso, Chile
(Dated: November 12, 2014)
We propose a model based on the SU (5) grand unification with an extra Z2 ⊗ Z2′ ⊗ Z2′′ ⊗ Z4 ⊗ Z12
flavor symmetry, which successfully describes the observed SM fermion mass and mixing pattern.
The observed quark mass and mixing pattern is caused by the Z4 and Z12 symmetries, which are
broken at very high scale by the SU (5) scalar singlets σ and χ, charged respectively under these
symmetries and which acquire VEVs at the GUT scale. The light neutrino masses are generated
via a type I seesaw mechanism with three heavy Majorana neutrinos. The model has in total 17
effective free parameters, from which 2 are fixed and 15 are fitted to reproduce the experimental
values of the 18 physical parameters in the quark and lepton sectors. The model predictions for
both quark and lepton sectors are in excellent agreement with the experimental data.
I.
INTRODUCTION
In spite of the Standard Model (SM) great success in describing electroweak phenomena, recently confirmed with the
LHC discovery of a 126 GeV Higgs boson [1], it has many open questions [2, 3]. Among the most pressing are the
smallness of neutrino masses, the fermion mass and mixing hierarchy, and the existence of the three generations of
fermions. The existing pattern of fermion masses goes over a range of five orders of magnitude in the quark sector
and a much wider range when neutrinos are included. While the mixing angles in the quark sector are very small,
in the lepton sector two of the mixing angles are large, and one mixing angle is small. This suggests a different kind
of New Physics for the neutrino sector from the one present in the quark mass and mixing pattern. Experiments
with solar, atmospheric and reactor neutrinos have brought clear evidence of neutrino oscillations from the measured
non vanishing neutrino mass squared splittings. This brings compelling and indubitable evidence that at least two of
the neutrinos have non vanishing masses, much smaller, by many orders of magnitude, than the SM charged fermion
masses, and that the three neutrino flavors mix.
The global fits of the available data from neutrino oscillation experiments Daya Bay [4], T2K [5], MINOS [6], Double
CHOOZ [7] and RENO [8], constrain the neutrino mass squared splittings and mixing parameters, as shown in Tables
I and II (based on Ref. [9]) for the normal (NH) and inverted (IH) hierarchies of the neutrino mass spectrum. These
facts might suggest that the tiny neutrino masses can be related to a scale of New Physics that, in general, is not
related to the scale of Electroweak Symmetry Breaking (EWSB) v = 246 GeV.
Parameter ∆m221 (10−5 eV2 ) ∆m231 (10−3 eV2 )
Best fit
1σ range
2σ range
3σ range
7.60
7.42 − 7.79
7.26 − 7.99
7.11 − 8.11
2.48
2.41 − 2.53
2.35 − 2.59
2.30 − 2.65
sin2 θ12
exp
sin2 θ23
exp
sin2 θ13
exp
0.323
0.567
0.0234
0.307 − 0.339 0.439 − 0.599 0.0214 − 0.0254
0.292 − 0.357 0.413 − 0.623 0.0195 − 0.0274
0.278 − 0.375 0.392 − 0.643 0.0183 − 0.0297
Table I: Range for experimental values of neutrino mass squared splittings and leptonic mixing parameters, taken from Ref.
[9], for the case of normal hierarchy.
The flavour puzzle of the SM indicates that New Physics has to be advocated to explain the prevailing patterm of
fermion masses and mixings. To tackle the limitations of the SM, various extensions of the SM including larger scalar
and/or fermion sector as well as extended gauge group with additional flavor symmetries, have been proposed in the
∗ Electronic
address: [email protected]
address: [email protected]
‡ Electronic address: [email protected]
† Electronic
arXiv:1411.2912v1 [hep-ph] 11 Nov 2014
Nonlinear evolution of density and flow perturbations
on a Bjorken background
Nikolaos Brouzakisa , Stefan Floerchingerb , Nikolaos Tetradisa,b , Urs Achim
Wiedemannb
a
b
Department of Physics, University of Athens, Zographou 157 84, Greece
Physics Department, Theory Unit, CERN, CH-1211 Gen`eve 23, Switzerland
E-mail: [email protected], [email protected],
[email protected], [email protected]
Abstract: Density perturbations and their dynamic evolution from early to late times
can be used for an improved understanding of interesting physical phenomena both in cosmology and in the context of heavy-ion collisions. We discuss the spectrum and bispectrum
of these perturbations around a longitudinally expanding fireball after a heavy-ion collision.
The time-evolution equations couple the spectrum and bispectrum to each other, as well
as to higher-order correlation functions through nonlinear terms. A non-trivial bispectrum
is thus always generated, even if absent initially. For initial conditions corresponding to
a model of independent sources, we discuss the linear and nonlinear evolution is detail.
We show that, if the initial conditions are sufficiently smooth for fluid dynamics to be
applicable, the nonlinear effects are relatively small.
Single-inclusive particle production in proton-nucleus collisions at next-to-leading
order in the hybrid formalism
Tolga Altinoluk1 , N´estor Armesto1 , Guillaume Beuf1,2 , Alex Kovner3 and Michael Lublinsky2
arXiv:1411.2869v1 [hep-ph] 11 Nov 2014
1
Departamento de F´ısica de Part´ıculas and IGFAE,
Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Galicia-Spain
2
Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
3
Physics Department, University of Connecticut,
2152 Hillside Road, Storrs, CT 06269-3046, USA
We reconsider the perturbative next-to-leading calculation of the single inclusive hadron production in the framework of the hybrid formalism, applied to hadron production in proton-nucleus
collisions. Our analysis, performed in the wave function approach, differs from the previous works
in three points. First, we are careful to specify unambiguously the rapidity interval that has to
be included in the evolution of the leading-order eikonal scattering amplitude. This is important,
since varying this interval by a number of order unity changes the next-to-leading order correction
that the calculation is meant to determine. Second, we introduce the explicit requirement that fast
fluctuations in the projectile wave function which only exist for a short time are not resolved by
the target. This Ioffe time cutoff also strongly affects the next-to-leading order terms. Third, our
result does not employ the approximation of a large number of colors. Our final expressions are
unambiguous and do not coincide at next-to-leading order with the results available in the literature.
I.
INTRODUCTION AND CONCLUSIONS
It has been suggested thirty years ago [1], that at high energies hadronic structure is considerably different from that
at lower energies as hadrons exhibit perturbative saturation. Observation of saturation is of course a very interesting
possibility, as it would open a door for exploring a qualitative new regime of QCD - the regime of dense saturated
states, which is nevertheless perturbative in the sense that the relevant coupling constant remains small.
There has been a lot of activity in the last 20 years to try to better understand this regime theoretically. With
the advent of the Relativistic Heavy Ion Collider and, later, the Large Hadron Collider, many attempts to describe
available data in the framework of saturation have also been made.
It is fair to say that at the moment we do not have a clear understanding, whether effects of saturation (or
Color Glass Condensate (CGC), as its weak coupling implementation [2–7]) have already been seen in the current
experiments, although some saturation-based calculations provide good description of data (e.g. [8–13]). One of
the major reasons for this, is that the calculational precision of the saturation based approaches is still far from
satisfactory. For example, only a small (although important) part of next-to-leading order corrections (the running
coupling effects) is presently included in numerical implementations of high-energy evolution [14] even if the full result
is already available [15–18]. Calculation of various observables, like inclusive hadroproduction [19], photoproduction
[20], etc. has also been mostly confined to leading order in the strong coupling constant αs .
There is therefore an urgent need to improve the accuracy of the CGC-based calculations. Efforts in this direction
have been made in recent years, with the calculation of NLO corrections to several observables, like deep inelastic
scattering [21, 22], or single hadroproduction cross section at forward rapidities [23, 24] in the so called ”hybrid”
formalism [25]. However, numerical studies have yet been performed only in the latter case, and indicate very strong
effects of the NLO corrections, with cross sections even becoming negative at moderate transverse momenta [26, 27].
The recent followup [28] to [27] underscores the problem even more, since a change which is supposed to affect the
result only at next-to-next-to-leading order, modifies the NLO results significantly. There is also an ongoing discussion
on the correct choice of the factorization scale for the high-energy evolution [29, 30], and on the eventual relevance of
additional collinear resummations at small x [31].
The purpose of this paper is to reanalyze the NLO calculation of inclusive hadron production using the wave
function approach employed in [23]. Such an analysis is necessary, since the calculations of [23] and [24] are not quite
complete. The most important element missing in [23, 24] is a treatment of the limitation on the phase space of
emissions due to finite life time of the low-x fluctuations, the so-called Ioffe time [32]. We rectify this deficiency of
the previous calculations and provide formulae which explicitly take into account this constraint.
We also address the question what is the rapidity to which the eikonal scattering amplitudes have to be evolved.
This point has not been addressed explicitly in [23], while [24] uses an heuristic argument based on the kinematics of
2 → 1 processes and [29] proposes a different solution.
The result of this work is a complete set of formulae for hadron production in the hybrid formalism, at NLO
accuracy, including all channels. We implement in our formulae the Ioffe time restriction which ensures that only
TTP14-030,
SFB/CPP-14-87
Standard Model beta-functions to
three-loop order and vacuum stability
Max F. Zoller a,1 ,
arXiv:1411.2843v1 [hep-ph] 11 Nov 2014
a
Institut für Theoretische Teilchenphysik (TTP), Karlsruhe Institute for Technology
1: [email protected]
Abstract
Since the discovery of a Higgs particle [1, 2] the effective Higgs potential of the Standard
Model or extensions and the stability of the ground state corresponding to its minimum
at the electroweak scale have been subject to a lot of investigation. The vacuum
expectation value of the scalar SU(2) doublet field in the Standard Model, which is
responsible for the masses of elementary particles, may in fact not be at the global
minimum of the effective Higgs potential. The question whether there is a deeper
minimum at some large scale is closely linked to the behaviour of the running quartic
Higgs self-interaction λ(µ). In this talk an update on the analysis of the evolution
of this coupling is given. We use three-loop beta-functions for the Standard Model
couplings, two-loop matching between on-shell and MS quantities and compare the
theoretical precision achieved in this way to the precision in the latest experimental
values for the key parameters.
1
Introduction: The stability of the Standard Model
ground state
In the Standard Model (SM) of particle physics fermions interact via the exchange of
gauge bosons. The strength of these interactions is given by the coupling constants
gs for the QCD
partand g2 , g1 for the electroweak part. Furthermore, a scalar SU(2)
Φ1
doublet Φ =
is introduced which couples to the SU(2) gauge bosons via the
Φ2
coupling g2 and to the fermions via Yukawa couplings, the top-Yukawa coupling yt
being the strongest. The quartic self-coupling λ of the field Φ appears in the classical
Higgs potential
2
V (Φ) = m2 Φ† Φ + λ Φ† Φ .
(1)
0
For m2 < 0 the doublet Φ aquires a vacuum expectation value (VEV) hΦi = √12
v
in the minimum of the classical Higgs potential (Fig. 1 (a)). The masses of the quarks,
1
arXiv:1411.2840v1 [hep-ph] 11 Nov 2014
HEPHY-PUB 942/14
UWThPh-2014-26
h0 → c¯c as a test case for quark flavor violation in the
MSSM
A. Bartl1 , H. Eberl2 , E. Ginina2 , K. Hidaka3,4 ,
W. Majerotto2
1
2
Universit¨
at Wien, Fakult¨
at f¨
ur Physik, A-1090 Vienna, Austria
¨
Institut f¨
ur Hochenergiephysik der Osterreichischen
Akademie der Wissenschaften, A-1050
Vienna, Austria
3 Department of Physics, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan
4 RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
Abstract
We compute the decay width of h0 → c¯
c in the MSSM with quark flavor violation
(QFV) at full one-loop level adopting the DR renormalisation scheme. We study the
effects of c˜ − t˜ mixing, taking into account the constraints from the B meson data.
We show that the full one-loop corrected decay width Γ(h0 → c¯
c) is very sensitive to
the MSSM QFV parameters. In a scenario with large c˜L,R − t˜L,R mixing Γ(h0 → c¯
c)
can differ up to ∼ ±35% from its SM value. After estimating the uncertainties of
the width, we conclude that an observation of these SUSY QFV effects is possible
at an e+ e− collider (ILC).
arXiv:1411.2834v1 [hep-ph] 11 Nov 2014
TUM-HEP-967-14
Phenomenology of Baryogenesis from
Lepton-Doublet Mixing
Bj¨orn Garbrecht1 and Ignacio Izaguirre1,2
1
Physik Department T70, James-Franck-Straße,
Technische Universit¨at M¨
unchen, 85748 Garching, Germany
2
Max-Planck-Institut f¨
ur Physik (Werner-Heisenberg-Institut), F¨ohringer Ring 6,
80805 M¨
unchen, Germany
Abstract
Mixing lepton doublets of the Standard Model can lead to lepton flavour asymmetries in the Early Universe. We present a diagrammatic representation of this
recently identified source of CP violation and elaborate in detail on the correlations between the lepton flavours at different temperatures. For a model where
two sterile right-handed neutrinos generate the light neutrino masses through the
see-saw mechanism, the lower bound on reheat temperatures in accordance with
9
the observed baryon asymmetry turns out to be >
∼ 1.2 × 10 GeV. With three
right-handed neutrinos, substantially smaller values are viable. This requires however a tuning of the Yukawa couplings, such that there are cancellations between
the individual contributions to the masses of the light neutrinos.
1
Introduction
Observational and theoretical studies of mixing and oscillations are typically concerned
with neutral particle states. Important examples are neutral meson mixing, the oscillations of Standard Model (SM) neutrinos [1] and Leptogenesis through the mixing of sterile right-handed neutrinos (RHNs) in the early Universe [2–5]. In contrast, for charged
particles in the SM at vanishing temperature, mass degeneracies between different states
are not strong enough to produce observable phenomena of mixing and oscillations. This
does however not preclude the fact that these effects are present in principle. Moreover,
it has been demonstrated that the mixing of lepton doublets (which are gauged) can
be of importance for Leptogenesis [6–10]: At high temperatures, the asymmetries are in
general produced as superpositions of the lepton doublet flavour eigenstates of the SM.
In the SM flavour basis, this can be described in terms of off-diagonal correlations in the
Muon anomalous magnetic moment in a SU (4) ⊗ U (1)N model without exotic electric charges.
D. Cogolloa∗
a
Departamento de Fisica, Universidade Federal de Campina Grande,
Caixa Postal 10071, 58109-970, Campina Grande, PB, Brazil
arXiv:1411.2810v1 [hep-ph] 11 Nov 2014
We study an electroweak gauge extension of the standard model, so called 3-4-1 model, which does not
contain exotic electric charges and it is anomaly free. We discuss phenomenological constraints of the model
and compute all the corrections to the muon magnetic moment. Mainly, we discuss different mass regimes and
their impact on this correction, deriving for the first time direct limits on the masses of the neutral fermions and
charged vector bosons. Interestingly, the model could address the reported muon anomalous magnetic moment
excess, however it would demands a rather low scale of symmetry breaking, far below the current electroweak
constraints on the model. Thus, if this excess is confirmed in the foreseeable future by the g-2 experiment at
FERMILAB, this 3-4-1 model can be decisively ruled out since the model cannot reproduce a sizeable and
positive contribution to the muon anomalous magnetic moment consistent with current electroweak limits.
∗
[email protected]
2
I.
INTRODUCTION
The unified description of the electromagnetic and weak interactions by a single theory, so called Standard Model (SM),
certainly is one of the major achievements in this century. The model proposed by Glashow, Salam, and Weinberg in the middle
sixties, has been extensively tested during the last decades with tremendous success. The discovery of neutral weak interactions
and the production of intermediate vector bosons with the predicted properties increased our confidence in the model. Besides,
now the Higgs discovery has anchored, the Standard Model is undoubtedly the best particle physics model we have at our
disposal. However, neutrino masses and dark matter are robust experimental and observational indications that the SM must be
extended. Furthermore, the excess over the SM prediction on the muon magnetic moment, which is the most precisely measured
quantity in particle physics, provides a compelling case for physics beyond the SM. Such issues, have triggered a multitude of
extensions of the standard model trying to fully or partially address those matters.
In this work we will focus on the muon magnetic moment in the context of an electroweak extension of the SM, called
3-4-1 for short, which is based on the SU (3)c SU (4)L U (1)X gauge symmetry. In general, 3-4-1 models have been proposed to
provide an elegant solution to the neutrinos masses, by placing the leptons ν, e, ν c and ec in the same multiplet of a SU (4)L [1].
As in the case of the gauge symmetry SU (3)c SU (3)L U (1)N , here the number of fermion families must be an integral multiple
of fundamental color which is three, in order to the required anomaly cancellation [2]. All these result in an exact family number
of three, coinciding with the observation. Since the third family of quarks transforms under SU (4)L differently from the first
two, this could possibly be the reason to why top quark is so heavy. The SU (4)L extension can also provide some insights
of electric charge quantization observed in the nature [3]. The 3-4-1 model is a natural gauge extension of the so called 3-3-1
models, which are based on the SU (3)c ⊗ SU (3)L ⊗ U (1)N gauge symmetry. Some of those models provide plausible dark
matter candidates in the context of Higgs Portal [4] and Z 0 portal [5], despite the direct dark matter detection controversy [6],
also explaining possibly the Galactic Center excess observed in the Fermi-LAT data [7], address the dark radiation non-thermal
dark matter production [8], and even reproducing the mild Hγγ excess [9], among others [10, 11].
There are several versions of 3-4-1 models, and each of them inherits the features of their respective 3-3-1 models and
therefore such models are in principle indistinguishable from the 3-3-1 models at low scale. Similarly, if the scale of symmetry
breaking of the 3-4-1 model is high enough, at sufficiently low energies 3-4-1 model are equivalent to the SM as well. Albeit,
there are remnants in the spectrum that might be important to observables such the muon magnetic moment, which is one of the
most precisely measured quantities in particle physics. Differently from other observables the muon magnetic moment might be
sensitive to new physics effects at very high energy scales. Several works have been put forth in this direction concerning 3-3-1
models [12], but there is lack of results in the context of 3-4-1 frameworks [13].
Our goal here is to assess whether a 3-4-1 model without exotic electric charges and heavy neutral fermions is capable of
addressing the excess reported in the muon magnetic moment with respect to the SM prediction, and obtain robust limits in the
model in light of the upcoming g-2 experiment at Fermilab, which might reach a 5σ deviation from the SM. We will not dwell
on unnecessary details. Thus we briefly discuss the key aspects of this model relevant for our reasoning and then present our
results.
II.
MODEL SU (4)L ⊗ U (1)N
A.
Fermionic Content
The lepton representations in this model are [14],


να
 e 
fαL =  α  ∼ (1, 4∗ , −1/2)
N
α
Nα0
(eαR ) ∼ (1, 1, −2) ,
(1)
L
with α = 1, 2, 3. In order to cancel all the quirial anomalies two left handed quark families must transform as 4-plets, and the
other one as an anti-4-plet


ui
 d 
QiL =  i  ∼ (3, 4, −1/6)
Di
Di0 L


d3
u 
Q3L =  3  ∼ (3, 4∗ , 5/6)
U
U0 L
(2)
Electroweak Corrections to Photon Scattering, Polarization and Lensing
in a Gravitational Background and the Near Horizon Limit
arXiv:1411.2804v1 [hep-ph] 11 Nov 2014
(1) Claudio
Corian`
o,
(1) Dipartimento
(1) Luigi
(1) Matteo
Delle Rose,
Maria Maglio and
(1,2) Mirko
Serino
di Matematica e Fisica ”Ennio De Giorgi”, Universit`
a del Salento and
INFN-Lecce, Via Arnesano, 73100 Lecce, Italy
(2) Institute
of Nuclear Physics
Polish Academy of Sciences, ul. Radzikowskiego 152 31-342 Krakow, Poland
Abstract
We investigate the semiclassical approach to the lensing of photons in a spherically symmetric
gravitational background, starting from Born level and include in our analysis the radiative corrections
obtained from the electroweak theory for the graviton/photon/photon vertex. In this approach, the
cross section is related to the angular variation of the impact parameter (b), which is then solved for b as
a function of the angle of deflection, and measured in horizon units (bh ≡ b/(2GM )). Exact numerical
solutions for the angular deflection are presented. The numerical analysis shows that perturbation
theory in a weak background agrees with the classical Einstein formula for the deflection already at
distances of the order of 20 horizon units (∼ 20 bh ) and it is optimal in the description both of very
strong and weak lensings. We show that the electroweak corrections to the cross section are sizeable,
becoming very significant for high energy gamma rays. Our analysis covers in energy most of the
photon spectrum, from the cosmic microwave background up to very high energy gamma rays, and
scatterings with any value of the photon impact parameter. We also study the helicity-flip photon
amplitude, which is of O(α2 ) in the weak coupling α, and its massless fermion limit, which involves the
exchange of a conformal anomaly pole. The corresponding cross section is proportional to the Born
level result and brings to a simple renormalization of Einsten’s formula.
1
[email protected], [email protected], [email protected], [email protected]
1
1
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–6
Signs for new physics in the recent LHCb data?I
Tobias Hurth
arXiv:1411.2786v1 [hep-ph] 11 Nov 2014
PRISMA Cluster of Excellence, Institute for Physics (THEP)
Johannes Gutenberg University, D-55099 Mainz, Germany
Farvah Mahmoudi
Universit´e de Lyon, Universit´e Lyon 1, F-69622 Villeurbanne Cedex, France;
Centre de Recherche Astrophysique de Lyon, Saint Genis Laval Cedex, F-69561, France;
CNRS, UMR 5574; Ecole Normale Sup´erieure de Lyon, France
CERN Theory Division, Physics Department, CH-1211 Geneva 23, Switzerland
Abstract
We comment on some tensions with the Standard Model predictions in the recent LHCb data.
1. Introduction
With the first measurement of new angular observables in the exclusive decay B → K ∗ µ+ µ− based on the
1 fb−1 dataset, LHCb has found a 4.0σ local discrepancy in one of the q2 bins for one of the angular observables [1], namely in the bin q2 ∈ [4.3, 8.63] GeV2
0
of the observable P5 . The latter belongs to the set of
optimised observables in which form factor dependence
cancels out to first order. LHCb results are compared
here with the theoretical predictions in Ref. [2]. Intriguingly, other smaller but consistent deviations are also
present in other observables [1].
In the low-q2 region, the up-to-date description of
exclusive heavy-to-light B → K ∗ µ+ µ− decays is the
method of QCD-improved Factorisation (QCDF) and
its field-theoretical formulation of Soft-Collinear Effective Theory (SCET). In the combined limit of a heavy
b-quark and of an energetic K ∗ meson, the decay amplitude factorises to leading order in Λ/mb and to all
I Based on talks given by T.H. at the Fifth Workshop on Theory,
Phenomenology and Experiments in Flavour Physics, Capri, 23-25
May 2014 and at the FPCP 2014 conference on Flavor Physics and
CP Violation, Marseille, 25-30 May 2014.
Email addresses: [email protected] (Tobias Hurth),
[email protected] (Farvah Mahmoudi)
orders in α s into process-independent non-perturbative
quantities like B → K ∗ form factors and light-cone
distribution amplitudes (LCDAs) of the heavy (light)
mesons and perturbatively calculable quantities, which
are known to O(α1s ) [3, 4]. Further, the seven a priori independent B → K ∗ QCD form factors reduce to
two universal soft form factors ξ⊥,k [5]. The factorisation formula applies well in the dilepton mass range
1 GeV2 < q2 < 6 GeV2 .
Taking into account all these simplifications the various K ∗ spin amplitudes at leading order in ΛQCD /mb
and αS turn out to be linear in the soft form factors ξ⊥,k
and also in the short-distance Wilson coefficients. As
was explicitly shown in Refs. [6, 7], these simplifications allow to design a set of optimised observables, in
which any soft form factor dependence (and its corresponding uncertainty) cancels out for all low dilepton
mass squared q2 at leading order in αS and ΛQCD /mb .
An optimised set of independent observables was constructed in Refs. [2, 8], in which almost all observables
are free from hadronic uncertainties which are related to
the form factors.
However, the soft form factors are not the only source
of hadronic uncertainties in these angular observables.
It is well-known that within the QCDF/SCET approach,
arXiv:1411.2780v1 [hep-ph] 11 Nov 2014
Properties of effective massive Yang-Mills theory in the limit of
vanishing vector boson mass
J. Gegelia1, 2 and U.-G. Meißner3, 4
1
Institut f¨
ur Theoretische Physik II,
Ruhr-Universit¨at Bochum, D-44780 Bochum, Germany
2
Tbilisi State University, 0186 Tbilisi, Georgia
3
Helmholtz Institut f¨
ur Strahlen- und Kernphysik and Bethe Center for Theoretical Physics,
Universit¨at Bonn, D-53115 Bonn, Germany
4
Institute for Advanced Simulation,
Institut f¨
ur Kernphysik and J¨
ulich Center for Hadron Physics,
Forschungszentrum J¨
ulich, D-52425 J¨
ulich, Germany
(Dated: 26 September, 2014)
Abstract
Two-loop corrections to the pole mass of the vector boson and the pole masses and the magnetic
moments of fermions are calculated in the framework of an effective field theory of massive YangMills fields interacting with fermions. It is shown that the limit of vanishing vector boson mass is
finite for all these quantities. Implications of the obtained results are discussed.
PACS numbers: 03.70.+k,11.25.Db,11.15.-q
1
FImP Miracle of Sterile Neutrino Dark Matter by Scale Invariance
Zhaofeng Kang1, ∗
arXiv:1411.2773v1 [hep-ph] 11 Nov 2014
1
School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Korea
(Dated: November 12, 2014)
The standard model (SM) with sterile neutrinos provides the simplest idea to understand nonzero
neutrino masses. As a bonus, the lightest sterile neutrino N1 , even in the absence of a protective
symmetry, can be a dark matter (DM) candidate provided that it is as light as the keV scale. We
observe that if this idea is realized in the scale invariant SM, which may address the hierarchy
problem, extra singlet scalars S with nonzero vacuum expected value (VEV) should be introduced
to give Majorana masses for the sterile neutrinos. Such a fact yields an attractive picture: Given
hSi ∼TeV via the Coleman-Weinberg mechanism, which is strongly favored by Higgs phenomenologies, the correct orders of DM mass (by dynamics instead of hand) and DM relic density (by freeze-in
instead of oscillation) are surprisingly addressed by the same vertex SN1 N1 . This coincidence is
an even stronger version of the WIMP miracle and dubbed as FImP miracle. Interestingly, a 7.1
keV N1 with correct relic density, that can explain the recent 3.55 keV X−ray line, lies in the bulk
parameter space of our model.
I.
INTRODUCTION AND MOTIVATION
Developments of particle physics are both theoretically and experimentally oriented. Therefore, when we are blindly
exploring new physics beyond the standard model (SM), we should try our best to keep eyes on guidelines from both
sides. Thus far, the hierarchy problem and existence of dark matter (DM), nonzero neutrino masses respectively
provide the strongest guidelines from each side. A framework that could address them unifiedly, out of question, must
be of special interest. But usually they are not inherently related. Supersymmetry (SUSY) is a famous example. It
can elegantly solve the hierarchy problem and at the same time present a DM candidate, but it is not a theory of
neutrinos. In this article we will follow another line, i.e., the (classical) scale invariance (SI) that is potential to be a
protecting symmetry on the weak scale [1] and inspires a number of studies [3–10]. Along this line, we will find that
those three aspects can be closely related.
We start from some thoughts about DM, from which we will spell out how they are related. Despite of a lot
of experimental efforts, people still have not acquired much confirmative information about the particle natural of
DM. Since the DM (in)direct detections are mainly based on the weakly interacting massive particle (WIMP) DM
hypothesis, the null results [2] begin to challenge this paradigm. Now it is at the right time to reexamine the theoretical
basis of WIMP DM. Or more ambitious, we may should figure out what kind of DM is theoretically preferred and
accordingly suggest new focus of DM detections. We would like to follow the ensuing basic questions about DM.
• Firstly, why is it there? Obviously, a DM candidate that is predicted rather than introduced would be more
attractive. A good case in point is the lightest sparticle (LSP) in SUSY and axion from the Pecci-Quinn models
aiming at solving the strong CP-problem. Another example is the core of this paper, the lightest right-handed
neutrino (RHN) N1 , or sterile neutrino [11]. RHNs are originally introduced to explain the nonzero neutrino
masses, but they are neutral and thus potential to provide a DM candidate.
• Secondly, why is it stable (or at least sufficiently stable)? Again, we advocate a mechanism that naturally
guarantees DM stability rather than imposing a protective symmetry like Z2 by hand. For instance, such a
Z2 may be an accidental symmetry due to the field content along with the space-time and gauge symmetries
of the model, see an example based on SI [10] 1 . In this sense even the LSP, the most promising WIMP DM
candidate, is criticized for its demand for the so-called R−parity. By contrast, the sterile neutrino N1 , given a
mass ∼ O(keV), can have lifetime at cosmic time scale even in the absence of an exact protective symmetry.
Note that in this way of understanding DM stability, DM is expected to be decaying, and DM lightness (far
below the weak scale) plays the key role in suppressing the decay rate.
∗ E-mail:
1
[email protected]
(Under some reasonable assumptions) it concludes that the only viable accidental DM (aDM) must be a singlet scalar. But this paper
is restricted to WIMP. Beyond it, a singlet fermion N is also viable, provided that its coupling to the visible sector is sufficiently weak,
¯
namely yN ℓΦN
with yN ≪ 1. For N introduced in this way is naturally identified with the lightest RHN.
b-τ Unification by Neutrinos
Takanao Tsuyuki
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan
arXiv:1411.2769v1 [hep-ph] 11 Nov 2014
Abstract
We show that Yukawa couplings of bottom quark and tau lepton can be unified at the grand
unification scale without supersymmetry. We consider arbitrary number of right-handed neutrinos.
Their masses and Yukawa couplings which satisfy the unification condition are shown.
Introduction.—Neutrino oscillations, which mean neutrinos have masses, are evidences for physics
beyond the Standard Model (SM). We know that at least two flavors of neutrinos have O(0.01-0.1)eV
masses. Their Majorana masses can be written as v 2 /M (v = 174.1GeV). We need M to be in the
desert between electroweak and planck scales, O(1015) GeV (seesaw scale). The neutrino masses can be
induced by singlet, right-handed neutrinos (type-I [1]), an SU(2) triplet scalar (type-II [2]) or SU(2)
triplet fermions (type-III seesaw [3]).
Near the seesaw scale, there may be another interesting phenomenon; unification of elementary
forces [4, 5]. If the SM gauge group GSM ≡ SU(3) × SU(2) × U(1) is embedded into one nonabelian
group, we can explain the charge quantization of quarks and leptons. The simplest grand unification
theory (GUT) is the model based on SU(5) gauge group [5], which is broken to GSM in one step.
By solving renormalization group equations (RGEs), the three gauge couplings indeed evolve toward
unification, but do not exactly meet at one scale. If some fields charged under GSM exist between
the electroweak scale and the GUT scale (MG ), unification is still possible. The cases of a scalar
representation 15H [6] and a fermion representation 24F [7–9] are especially interesting since they can
also explain the neutrino masses by type-II or type-I+III seesaw mechanisms.
In the SU(5) model, not only gauge couplings, but also eigenvalues of Yukawa coupling matrices of
down-type quarks and charged leptons are unified at MG . This unification condition cannot be satisfied
if we use known fields only [10]. In previous studies, dimension five operator is assumed for this
problem [11–13]. The contribution of the operator is . vMG /Λ. MG is bounded from below by nucleon
decay search [14], naively MG & 1015.4 GeV [9]. The GUT scale near this bound is phenomenologically
interesting and natural, because it may be tested by nucleon decay search [15] and is close to the
seesaw scale. If the GUT scale is 1015.5−16.0 GeV, and Λ ∼ 1019 GeV, the higher dimensional term gives
. 0.1GeV. This is suitable to adjust the first and the second generation Yukawa coupling unifications,
but too small for that of the third generation. We need some mechanism for yb = yτ , i.e., b-τ unification.
If there are right-handed neutrinos, the Yukawa couplings of neutrinos yν changes the RGEs of
Yukawa couplings of quarks and charged leptons [16]. In this paper, we show that if the yν = O(1), b-τ
unification is possible. This is not able in the cases of type-II and type-III seesaw because an SU(2)
triplet scalar and triplet fermions contribute to the running of yτ in the positive direction [13, 17]. We
consider 1-loop beta functions throughout this paper mainly for a large experimental error of mb . The
gauge couplings are assumed to be unified by adjoint fermions and a scalar, but the details of gauge
coupling unification does not essentially change our analysis of b-τ unification.
Gauge and Yukawa coupling unifications.—For gauge coupling unification, we assume that three
multiplets TF , TH ≡ (1, 3, 0), OF ≡ (8, 1, 0) (indicating representations under GSM and F (H) means
fermionic (Higgs) field) are much lighter than MG . These fields can be embedded into adjoint rep-
1
arXiv:1411.2766v1 [hep-ph] 11 Nov 2014
Neutrino Masses and Mixings from Continuous
Symmetries
Luca Merlo∗
Istituto de Física Teórica UAM/CSIC and Departamento de Física Teórica,
Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
E-mail: [email protected]
Flavour symmetries are fundamental tools in the search for an explanation to the flavour puzzle:
fermion mass hierarchies, the neutrino mass ordering, the differences between the mixing matrices in the quark and lepton sector, can all find an explanation in models where the fermion
generations undergo specific geometric relations. An overview on the implementation of continuous symmetries in the flavour sector is presented here, focussing on the lepton sector.
16th International Workshop on Neutrino Factories and Future Neutrino Beam Facilities - NUFACT2014,
25 -30 August, 2014
University of Glasgow, United Kingdom
∗ I acknowledge partial support by European Union FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011289442), by the Juan de la Cierva programme (JCI-2011-09244) and by the Spanish MINECOs “Centro de Excelencia
Severo Ochoa” Programme under grant SEV-2012-0249. Finally, I thank the organisers and the conveners of the NUFACT 2014 conference for the kind invitation and for their efforts in organising this enjoyable meeting.
c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
http://pos.sissa.it/
Continuous Flavour Symmetries
1. Introduction
Before the discovery of a non-vanishing reactor angle [1–5], discrete symmetries were deeply
implemented in the construction of flavour models to explain the flavour puzzle. In particular, it
was a common feature of this class of models the prediction in first approximation of the PMNS
matrix with a vanishing reactor angle and a maximal atmospheric one [6–10].
With a sizable reactor angle [11,12], these models underwent to a severe loss of attractiveness.
To achieve a model in agreement with the new data, a few strategies have been followed [13]: introduction of additional parameters in preexisting minimal models; implementation of features that
allow next order corrections only in specific directions in the flavour space; search for alternative
mixing patterns or flavour symmetries that lead already in first approximation to θ13 6= 0◦ (see for
example Refs. [14–22] and references therein). In summary, the latest neutrino data can still be
described in the context of discrete symmetries, but at the prize of fine-tunings and/or eccentric
mechanisms.
Sum rules among neutrino masses and mixing angles are usually present in these models
and are useful as tests at experiments [23–25]. Furthermore, studies on flavour violating observables [26–32], on the connection with astroparticle physics [33–35], on the parameter running [36–38] and on the role of the CP symmetry [39–43] have been performed to fully workout
this framework. On the other side, the scalar and messenger sectors of these models are in general very complicated [44–48], it is not easy to provide a successful description of the quark sector [49–52], and the selection of a specific discrete symmetry usually does not follow from a more
general criterium [53], but it is just a matter of taste.
Even if it is still worth to search for a realistic model based on discrete symmetries, the many
drawbacks suggest to investigate alternative approaches: here the focus will be on continuous symmetries such as the simplest Abelian U(1) or non-Abelian groups.
2. Abelian models
Models based on the Abelian U(1) group are sometimes preferred with respect to those based
on discrete symmetries for a series of reasons. First of all, the Abelian U(1) group is an element
already present in the Standard Model (SM) and in many beyond SM (BSM) theories. Furthermore,
it has been shown much time ago that the quark sector [54] is easily described in this context. In
addition, the formulation of a model based on the U(1) symmetry, in the supersymmetric context
as the holomorphicity of the superpotential simplifies the construction of the Yukawa interactions,
is simple and elegant:
- The flavour symmetry acts horizontally on leptons and the charges can be written as ec ∼
(nR1 , nR2 , 0) for the SU(2)L lepton singlets and as ` ∼ (nL1 , nL2 , 0) for the SU(2)L lepton doublets. The third lepton charges can be set to zero as only charge differences have an impact on mass hierarchies and on mixing angles. Furthermore, it is not restrictive to assume
nR1 > nR2 > 0 to fix the ordering of the charged leptons. The Higgs fields Hu,d are not charged
under U(1) to prevent flavour-violating Higgs couplings.
- Once leptons have U(1) charges, the Yukawa terms are no longer invariant under the action
of the flavour symmetry. To formally recover the invariance, a new scalar field (or more than
2
Shear Viscosity and Phase Diagram from Polyakov−Nambu−Jona-Lasinio model
Sanjay K. Ghosh,∗ Sibaji Raha,† Rajarshi Ray,‡ Kinkar Saha,§ and Sudipa Upadhaya¶
arXiv:1411.2765v1 [hep-ph] 11 Nov 2014
Center for Astroparticle Physics & Space Science,
Block-EN, Sector-V, Salt Lake, Kolkata-700091, INDIA
&
Department of Physics, Bose Institute,
93/1, A. P. C Road, Kolkata - 700009, INDIA
We discuss a detailed study of the variation of shear viscosity, η, with temperature and baryon
chemical potential within the framework of Polyakov−Nambu−Jona-Lasinio model. η is found to
depend strongly on the spectral width of the quasi-particles present in the model. The variation of η
across the phase diagram has distinctive features for different kinds of transitions. These variations
have been used to study the possible location of the Critical End Point (CEP), and cross-checked
with similar studies of variation of specific heat. Finally using a parameterization of freeze-out
surface in heavy-ion collision experiments, the variation of shear viscosity to entropy ratio has also
been discussed as a function of the center of mass energy of collisions.
PACS numbers: 12.38.Aw, 12.38.Mh, 12.39.-x
I.
INTRODUCTION
The relativistic heavy ion collision experiments provide us with the unique opportunity to understand the physics
of strongly interacting matter expected to be present in the universe after a few microseconds of the big bang, and
possibly present in the interior of neutron stars. In the experiments, two heavy ions colliding at relativistic energies
are expected to form a fireball consisting of deconfined quarks and gluons, popularly known as the Quark-gluon
plasma (QGP). The search for QGP is continuing for almost last thirty years using several generations of higher
energy accelerators such as BEVALAC, AGS, SPS, RHIC and LHC while covering a large energy range of few AGeV
to few ATeV. Various observables, such as, J/Ψ suppression [1] and strangeness enhancement [2] had been proposed
as signatures of such state of matter. All such proposed signatures are based on medium’s properties which differed
substantially in hadronic and quark phases. Charmonium suppression, for example, was based on the properties
of deconfinement and plasma screening [1], whereas, strangeness enhancement was based on the chiral symmetry
restoration, which may be fully realized in QGP but only partially in a hadron gas [2, 3].
If the main interest lies in the identification of a new form of bulk matter then it is essential to choose observables
corresponding to unique collective properties of this matter. In heavy ion collisions, the primary observables of bulk
collectivity are the radial, azimuthal and longitudinal flow patterns of produced hadrons [4]. The different types of
collective flows are conveniently quantified in terms of the first few azimuthal Fourier components [5], vn (y, pT , Np , h)
of centrality selected triple differential inclusive distribution of hadrons, h. The centrality or impact parameter range
is usually specified by a range of associated multiplicities, from which the average number of participating nucleons,
Np , can be deduced. The azimuthal angle of the hadrons are measured relative to a globally determined estimate for
the collision reaction plane angle φ(M ).
The observation of elliptic flow in non-central heavy-ion collisions at RHIC, may be considered as the most important
evidence for hydrodynamical behavior of QGP. Elliptic flow occurs when the plasma collectively responds to pressure
gradients in the initial state. Hydrodynamic evolution converts the initial pressure gradients to velocity gradients
in the final state. In a heavy-ion collision one cannot control the deformation of the initial state. Instead, the
deformation of the plasma is determined by the shape of the overlapping region of the colliding nuclei. This shape
is governed by the impact parameter b. The impact parameter can be measured on an event-by-event basis using
the azimuthal dependence of the spectra of produced particles. Once the impact parameter direction is known, the
particle distribution can be expanded in Fourier components of the azimuthal angle φ. The Fourier coefficients (v2 ,
∗ Electronic
address:
address:
‡ Electronic address:
§ Electronic address:
¶ Electronic address:
† Electronic
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
arXiv:1411.2717v1 [hep-ph] 11 Nov 2014
Preprint typeset in JHEP style - HYPER VERSION
Contributions of the center vortices and vacuum
domain in potentials between static sources
Seyed Mohsen Hosseini Nejad and Sedigheh Deldar
Department of Physics,
University of Tehran, P.O. Box 14395/547, Tehran 1439955961, Iran
E-mail: [email protected], [email protected]
Abstract: In this paper, we study the role of the domain structure of the Yang Mills
vacuum. The Casimir scaling and N -ality are investigated in the potentials between static
sources in various representations for SU (2) and SU (3) gauge groups based on the domain
structure model using square ansatz for angle αC (x). We also discuss about the contributions of the vacuum domain and center vortices in the static potentials. As a result, the
potentials obtained from vacuum domains agree with Casimir scaling better than the ones
obtained from center vortices. The reasons of these observations are investigated by studying the behavior of the potentials obtained from vacuum domains and center vortices and
the properties of the group factors. Then, the vacuum domains in SU (N ) and G(2) gauge
groups are compared and one argue that the G(2) vacuum is filled with center vortices of
its subgroups.
Keywords: Confinement, domain structure model, Casimir scaling, vacuum domains,
center vortices.
November 12, 2014
1:24
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Xing
page 1
Xing
page 2
Chapter 1
arXiv:1411.2713v1 [hep-ph] 11 Nov 2014
Quark Mass Hierarchy and Flavor Mixing Puzzles
Zhi-zhong Xing∗
1) Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049;
2) Center for High Energy Physics, Peking University, Beijing 100080, P.R. China.
The fact that quarks of the same electric charge possess a mass hierarchy is
a big puzzle in particle physics, and it must be highly correlated with the
hierarchy of quark flavor mixing. This review article is intended to provide
a brief description of some important issues regarding quark masses, flavor
mixing and CP violation. A comparison between the salient features of
quark and lepton flavor mixing structures is also made.
1. A Brief History of Flavors
In the subatomic world the fundamental building blocks of matter are known
as “flavors”, including both quarks and leptons. Fifty years ago, the quark
model was born thanks to the seminal work done by Murray Gell-Mann1 and
George Zweig2 independently; and it turned out to be a great milestone in
the history of particle physics. The phrase “flavor physics” was first coined
by Harald Fritzsch and Murray Gell-Mann in 1971, when they were trying
different flavors of ice cream at one of the Baskin Robbins stores in Pasadena.
Since then quarks and leptons have been flavored.
There are totally twelve different flavors within the Standard Model (SM):
six quarks and six leptons. Table 1 is an incomplete list of the important
discoveries in flavor physics, which can give one a ball-park feeling of a
century of developments in particle physics. The SM contains thirteen free
flavor parameters in its electroweak sector: three charged-lepton masses,
six quark masses, three quark flavor mixing angles and one CP-violating
phase. Since the three neutrinos must be massive beyond the SM, one has
to introduce seven (or nine) extra free parameters to describe their flavor
properties: three neutrino masses, three lepton flavor mixing angles and one
∗ E-mail:
[email protected]
1
November 12, 2014
1:24
World Scientific Review Volume - 9.75in x 6.5in
2
Zhi-zhong Xing
Table 1. An incomplete list of some important discoveries in the 100-year
developments of flavor (quark and lepton) physics.3
Discoveries of lepton flavors, quark flavors and weak CP violation
1897
1919
1932
1933
1937
1947
1956
1962
1964
1974
1975
1977
1995
2001
2001
electron (Thomson4 )
proton (up and down quarks) (Rutherford5 )
neutron (up and down quarks) (Chadwick6 )
positron (Anderson7 )
muon (Neddermeyer and Anderson8 )
Kaon (strange quark) (Rochester and Butler9 )
electron antineutrino (Cowan et al.10 )
muon neutrino (Danby et al.11 )
CP violation in s-quark decays (Christenson et al.12 )
charm quark (Aubert et al.13 and Abrams et al.14 )
tau (Perl et al.15 )
bottom quark (Herb et al.16 )
top quark (Abe et al.17 and Abachi et al.18 )
tau neutrino (Kodama et al.19 )
CP violation in b-quark decays (Aubert et al.20 and Abe et al.21 )
(or three) CP-violating phase(s), corresponding to their Dirac (or Majorana)
nature a . So there are at least twenty flavor parameters at low energies. Why
is the number of degrees of freedom so big in the flavor sector? What is the
fundamental physics behind these parameters? Such puzzles constitute the
flavor problems in modern particle physics.
2. Quark Mass Hierarchy
Quarks are always confined inside hadrons, and hence the values of their
masses cannot be directly measured. The only way to determine the masses
of six quarks is to study their impact on hadron properties based on QCD.
Quark mass parameters in the QCD and electroweak Lagrangians depend
both on the renormalization scheme adopted to define the theory and on
the scale parameter µ — this dependence reflects the fact that a bare
quark is surrounded by a cloud of gluons and quark-antiquark pairs. In the
limit where all the quark masses vanish, the QCD Lagrangian possesses an
SU(3)L × SU(3)R chiral symmetry, under which the left- and right-handed
quarks transform independently. The scale of dynamical chiral symmetry
breaking (i.e., Λχ ≃ 1 GeV) can therefore be used to distinguish between
a In
this connection we have assumed the 3 × 3 lepton flavor mixing matrix U to be unitary for the
sake of simplicity. Whether U is unitary depends on the mechanism of neutrino mass generation.
UH-511-1239-2014
CETUP2014-004
arXiv:1411.2634v1 [hep-ph] 10 Nov 2014
Strange Brew:
Charged Mediators in Dark Matter Scattering with Nuclei
Chris Kelso,1 Jason Kumar,2 Pearl Sandick,3 and Patrick Stengel
2
1
Department of Physics, University of North Florida, Jacksonville, FL 32224, USA
Department of Physics and Astronomy, University of Hawai’i, Honolulu, HI 96822, USA
3
Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
2
Abstract
We consider a scenario, within the framework of the MSSM, in which dark matter is bino-like and
dark matter-nucleon spin-independent scattering occurs via the exchange of light squarks which
exhibit left-right mixing. We show that direct detection experiments such as LUX and SuperCDMS
will be sensitive to a wide class of such models through spin-independent scattering. Moreover,
these models exhibit properties, such as isospin violation, that are not typically observed for the
MSSM LSP if scattering occurs primarily through Higgs exchange. The dominant nuclear physics
uncertainty is the quark content of the nucleon, particularly the strangeness content.
1
NNNLO soft-gluon corrections for the top-quark pT and
rapidity distributions
arXiv:1411.2633v1 [hep-ph] 10 Nov 2014
Nikolaos Kidonakis
Kennesaw State University, Physics #1202,
Kennesaw, GA 30144, USA
Abstract
I present a calculation of next-to-next-to-next-to-leading-order (NNNLO) soft-gluon
corrections for differential distributions in top-antitop pair production in hadronic collisions. Approximate NNNLO (aNNNLO) results are obtained from soft-gluon resummation. Theoretical predictions are shown for the top-quark aNNNLO transverse momentum
(pT ) and rapidity distributions at LHC and Tevatron energies. The aNNNLO corrections
enhance previous results for the distributions but have smaller theoretical uncertainties.
1
Introduction
Top quark physics occupies a central role in particle theory and experiment. The top quark
has a unique position as the most massive elementary particle to have been discovered, and as
the only quark that decays before it can hadronize. Thus understanding the properties and
production rates of the top quark in the Standard Model is crucial for QCD, electroweak and
Higgs physics, and in searches for new physics.
The production of top quarks can happen either via top-antitop pair production or via
single-top production. While the total cross section is the simplest quantity to be calculated
and measured, differential distributions provide more detailed information on the production
processes. The top-quark transverse momentum (pT ) and rapidity distributions are particularly useful for discriminating signals of new physics. They have been measured at the Tevatron
[1, 2] and the LHC [3, 4] and are in excellent agreement with approximate NNLO (aNNLO)
calculations for the pT [5] and rapidity [6] distributions (see also [7] for updates). These aNNLO
calculations are based on the resummation of soft-gluon contributions in the double-differential
cross section at next-to-next-to-leading-logarithm (NNLL) accuracy in the moment-space approach in perturbative QCD [5, 6, 7] (for a review of resummation in various approaches see
the review paper in [8]).
The increasing precision of the measurements at the LHC and the upcoming run at 13 TeV
necessitate ever more precise theoretical calculations. For the total cross section the current
state-of-the-art is approximate NNNLO (aNNNLO) [9]. The purpose of the present paper is to
bring the calculation of the top-quark differential distributions to the same accuracy as the total
cross section in [9]. The resummation formalism for tt¯ production has already been presented
and discussed extensively in Refs. [5-10] and we refer the reader to those papers for more details
and further references. The accuracy, stability, and reliability of the resummation formalism
that we use has been amply demonstrated and discussed in [5, 7]; the soft-gluon corrections
approximate exact results for total cross sections and differential distributions at the per mille
accuracy level.
1
IPMU14-0337
LCTS/2014-45
arXiv:1411.2619v1 [hep-ph] 10 Nov 2014
Non-abelian Dark Matter Solutions for Galactic
Gamma-ray Excess and Perseus 3.5 keV X-ray Line
Kingman Cheung a,b,1 , Wei-Chih Huang c,2 , Yue-Lin Sming Tsai d,3
a
b
Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan
Division of Quantum Phases and Devices, School of Physics, Konkuk University, Seoul
143-701, Republic of Korea
c
d
Department of Physics and Astronomy, University College London, UK
Kavli IPMU (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
Abstract
We attempt to explain simultaneously the Galactic center gamma-ray excess and the 3.5
keV X-ray line from the Perseus cluster based on a class of non-abelian SU (2) DM models, in
which the dark matter and an excited state comprise a “dark” SU (2) doublet. The non-abelian
group kinetically mixes with the standard model gauge group via dimensions-5 operators. The
dark matter particles annihilate into standard model fermions, followed by fragmentation and
bremsstrahlung, and thus producing a continuous spectrum of gamma-rays. On the other
hand, the dark matter particles can annihilate into a pair of excited states, each of which
decays back into the dark matter particle and an X-ray photon, which has an energy equal to
the mass difference between the dark matter and the excited state, which is set to be 3.5 keV.
The large hierarchy between the required X-ray and γ-ray annihilation cross-sections can be
achieved by a very small kinetic mixing between the SM and dark sector, which effectively
suppresses the annihilation into the standard model fermions but not into the excited state.
1
[email protected]
[email protected]
3
[email protected]
2
arXiv:1411.2606v1 [hep-ph] 10 Nov 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
The topological long range order in QCD. Applications to heavy
ion collisions and cosmology.
Ariel R. Zhitnitsky1 , a
1
Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C. V6T 1Z1, Canada
Abstract. We argue that the local violation of P invariance in heavy ion collisions is a
consequence of the long range topological order which is inherent feature of strongly
coupled QCD. A similar phenomenon is known to occur in some topologically ordered
condensed matter systems with a gap. We also discuss possible cosmological applications
of this long range order in strongly coupled gauge theories. In particular, we argue that
the de Sitter behaviour might be dynamically generated as a result of the long range
order. In this framework the inflaton is an auxiliary field which effectively describes the
dynamics of topological sectors in a gauge theory in the expanding universe, rather than
a new dynamical degree of freedom.
1 Introduction
Recently it has become clear that quantum anomalies play very important role in the macroscopic
dynamics of relativistic fluids. Much of this progress is motivated by very interesting ongoing experiments on local P and CP violation in QCD as studied at RHIC [1–3] and, more recently, at the LHC
[4–7]. It is likely that the observed asymmetry is due to charge separation effect [8] as a result of the
chiral anomaly, see recent review [9] as an introduction to the subject. The ideas formulated in [8]
were further developed in follow up papers [10, 11] where the effect was coined as chiral magnetic
effect (CME).
We shall not discuss a number of subtle questions of the CME in the present work by referring to
a recent review [9]. Instead, we concentrate on a single crucial element for CME to be operational.
Namely, the key assumption of the proposal [8, 9] is that the region where the so-called hθ(~x, t)ind i , 0
should be much larger in size than the scale of conventional QCD fluctuations which have typical
correlation lengths of order ∼ Λ−1
x, t)ind parameter enters the effective lagrangian as follows,
QCD . The θ(~
g
aµν aρσ
Lθ = −θind q where q ≡ 64π
G
is the topological density operator, such that local P and
2 µνρσ G
CP invariance of QCD is broken on the scales where correlated state with hθ(~x, t)ind i , 0 is induced.
One should expect a number of P and CP violating effects taking place in a relatively large region
where hθ(~x, t)ind i , 0.
The first question to be addressed in the present work is as follows: what is the physics behind of
this long range order in the system with a gap ∼ ΛQCD ? As it is known, normally, if the system has a
gap, conventional correlation functions decay exponentially fast with a typical scale of order of Λ−1
QCD
2
a e-mail: [email protected]
FERMILAB-PUB-14-411-T
CERN-PH-TH-2014-219
arXiv:1411.2592v1 [hep-ph] 10 Nov 2014
Prepared for submission to JCAP
WIMPs at the Galactic Center
Prateek Agrawal,a Brian Batell,b Patrick J. Foxa and Roni Harnika
a Theoretical
b CERN,
Physics Department, Fermilab, Batavia, Illinois 60510, USA
Theory Division, CH-1211 Geneva 23, Switzerland
E-mail: [email protected], [email protected], [email protected], [email protected]
Abstract.
Simple models of weakly interacting massive particles (WIMPs) predict dark
matter annihilations into pairs of electroweak gauge bosons, Higgses or tops, which through
their subsequent cascade decays produce a spectrum of gamma rays. Intriguingly, an excess
in gamma rays coming from near the Galactic center has been consistently observed in Fermi
data. A recent analysis by the Fermi collaboration confirms these earlier results. Taking into
account the systematic uncertainties in the modelling of the gamma ray backgrounds, we
show for the first time that this excess can be well fit by these final states. In particular, for
annihilations to (W W , ZZ, hh, tt¯), dark matter with mass between threshold and approximately (165, 190, 280, 310) GeV gives an acceptable fit. The fit range for b¯b is also enlarged
to 35 GeV . mχ . 165 GeV. These are to be compared to previous fits that concluded only
much lighter dark matter annihilating into b, τ , and light quark final states could describe the
excess. We demonstrate that simple, well-motivated models of WIMP dark matter including
a thermal-relic neutralino of the MSSM, Higgs portal models, as well as other simplified
models can explain the excess.
PITT-PACC-1405
arXiv:1411.2588v1 [hep-ph] 10 Nov 2014
Top-Quark Initiated Processes
at High-Energy Hadron Colliders
Tao Han, Josh Sayre, and Susanne Westhoff
PITTsburgh Particle-physics Astro-physics & Cosmology Center (PITT-PACC),
Department of Physics & Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
Abstract
In hadronic collisions at high energies, the top-quark may be treated as a parton
inside a hadron. Top-quark initiated processes become increasingly important since
the top-quark luminosity can reach a few percent of the bottom-quark luminosity. In
the production of a heavy particle H with mass mH > mt , treating the top-quark
as a parton allows us to resum large logarithms log(m2H /m2t ) arising from collinear
splitting in the initial state. We quantify the effect of collinear resummation at the
14-TeV LHC and a future 100-TeV hadron collider, focusing on the top-quark openflavor process gg → tt¯H in comparison with tt¯ → H and tg → tH at the leading order
(LO) in QCD. We employ top-quark parton distribution functions with appropriate
collinear subtraction and power counting. We find that (1) Collinear resummation
enhances the inclusive production of a heavy particle with mH ≈ 5 TeV (0.5 TeV) by
more than a factor of two compared to the open-flavor process at a 100-TeV (14-TeV)
collider; (2) Top-quark mass effects are important for scales mH near the top-quark
threshold, where the cross section is largest. We advocate a modification of the ACOT
factorization scheme, dubbed m-ACOT, that consistently treats heavy-quark masses in
hadronic collisions with two initial heavy quarks; (3) The scale uncertainty of the total
cross section in m-ACOT is of about 20% at the LO. While a higher-order calculation
is indispensable for a precise prediction, the LO cross section is well described by the
process tt¯ → H using an effective factorization scale significantly lower than mH . We
illustrate our results by the example of a heavy spin-0 particle. Our main results also
apply to the production of particles with spin-1 and 2.
Activation cross-sections of deuteron induced nuclear reactions on neodymium
up to 50 MeV
F. T´ark´anyia , S. Tak´acsa , F. Ditr´oia,∗, A. Hermanneb , H. Yamazakic , M. Babac , A. Mohammadic , A.V. Ignatyukd
arXiv:1411.2760v1 [nucl-ex] 11 Nov 2014
a Institute
for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), Debrecen, Hungary
b Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), Brussels, Belgium
c Cyclotron Radioisotope Center (CYRIC), Tohoku University, Sendai, Japan
d Institute of Physics and Power Engineering (IPPE), Obninsk, Russia
Abstract
In the frame of a systematic study of activation cross sections of deuteron induced nuclear reactions on rare earths,
the reactions on neodymium for production of therapeutic radionuclides were measured for the first time. The excitation functions of the nat Nd(d,x) 151,150,149,148m,148g,146,144,143 Pm, 149,147,139m Nd, 142 Pr and 139g Ce nuclear reactions were
assessed by using the stacked foil activation technique and high resolution γ-spectrometry. The experimental excitation functions were compared to the theoretical predictions calculated with the modified model codes ALICE-IPPE-D
and EMPIRE-II-D and with the data in the TENDL-2012 library based on latest version of the TALYS code. The
application of the data in the field of medical isotope production and nuclear reaction theory is discussed.
Keywords: Nd target, deuteron activation, Pm, Nd and Ce radioisotopes, yield curves
1. Introduction
Activation cross-sections data of deuteron induced
nuclear reactions on neodymium are important for development of nuclear reaction theory and for different
practical applications. This study was performed in the
frame of the following ongoing research goals:
• To check the predictive power and benchmarking
of the different model codes of the nuclear reaction
theory. To contribute to the improvement of models for description of deuteron induced reactions
and to selection of more appropriate input parameters.
• To investigate the alternative production possibilities of standard and emerging therapeutic and diagnostic lanthanide radionuclides via charged particle induced reactions. In a search for new nuclides suitable for therapeutic purposes [1–8] the
radionuclide 149 Pm (T1/2 = 53.1 h), 141 Nd (T1/2 )
and 140 Nd (T1/2 = 3.37 d), were found to offer
some unique properties suitable for therapy and
the daughter nuclide 140 Pr (T1/2 = 3.4 min) brings
the additional advantage of in-vivo localization via
positron emission tomography (PET).
∗ Corresponding
author: [email protected]
Preprint submitted to NIM B
• To contribute to the extension of the database by
a systematic study of activation cross-sections of
deuteron induced nuclear reactions for biological
and industrial applications (accelerator technology,
thin layer activation, activation in space technology, etc.).
Here we present our results on activation cross-sections
on deuteron induced nuclear reactions on neodymium.
No earlier experimental data on nat Nd were found in
the literature. Only one earlier set of experimental
cross-section data was found on highly enriched 148 Nd
for investigation the isomeric ratios of the (d,2n) reactions [9]. Thick target yield data for production of
143,144,148
Pm at 22 MeV were reported by Dmitriev et al.
at 22 MeV [10].
2. Experiment and data evaluation
For measurements, the well-known activation
method, stacked foil irradiation technique and high
resolution γ-spectrometry was used. Nd metal foils
and NdO pellet targets, interleaved with Al foils for
monitoring of beam characteristics, were stacked
and irradiated at CYRIC (Sendai) and UCL (LLN)
cyclotrons. Complete excitation function was measured
November 12, 2014