Wed·Nov 25, 2015Wednesday·November 25, 2015

1. 01*

   Dark Matter from Unification of Color and Baryon Number

   Bartosz Fornal🇺🇸 · Tim M. P. Tait🇺🇸

   We analyze a recently proposed extension of the Standard Model based on the SU(4) x SU(2)_L x U(1)_X gauge group, in which baryon number is interpreted as the fourth color and dark matter emerges as a neutral partner of the ordinary quarks under SU(4). We show that under well-motivated minimal flavor-violating assumptions the particle spectrum contains a heavy dark matter candidate which is dominantly the partner of the right-handed top quark. Assuming a standard cosmology, the correct thermal relic density through freeze-out is obtained for dark matter masses around 2 - 3 TeV. We examine the constraints and future prospects for direct and indirect searches for dark matter. We also briefly discuss the LHC phenomenology, which is rich in top quark signatures, and investigate the prospects for discovery at a 100 TeV hadron collider.

   hep-phPRD(2016)·11 citations
2. 02*

   Anisotropic pressure in the quark core of a strongly magnetized hybrid star

   A. A. Isayev🇺🇦

   The impact of a strong magnetic field, varying with the total baryon number density, on thermodynamic properties of strange quark matter (SQM) in the core of a magnetized hybrid star is considered at zero temperature within the framework of the Massachusetts Institute of Technology (MIT) bag model. It is clarified that the central magnetic field strength is bound from above by the value at which the derivative of the longitudinal pressure with respect to the baryon number density vanishes first somewhere in the quark core under varying the central field. Above this upper bound, the instability along the magnetic field is developed in magnetized SQM. The total energy density, longitudinal and transverse pressures are found as functions of the total baryon number density.

   hep-phastro-ph.HEJ.Phys.Conf.Ser.(2015)·5 citations
3. 03*

   A novel Randall-Sundrum model with $S_3$ flavor symmetry

   A. E. Cárcamo Hernández🇨🇱 · I. de Medeiros Varzielas🇬🇧 · Nicolás A. Neill🇺🇸

   We propose a simple and predictive model of fermion masses and mixing in a warped extra dimension, with the smallest discrete non-Abelian group $S_3$ and the discrete symmetries $Z_2\otimes Z_4$. Standard Model fields propagate in the bulk and the mass hierarchies and mixing angles are accounted for the fermion zero modes localization profiles, similarly to the the Randall-Sundrum (RS) model. To the best of our knowledge, this model is the first implementation of an $S_3$ flavor symmetry in this type of warped extra dimension framework. Our model successfully describes the fermion masses and mixing pattern and is consistent with the current low energy fermion flavor data. The discrete flavor symmetry in our model leads to predictive mixing inspired textures, where the Cabbibo mixing arises from the down type quark sector whereas up type quark sector contributes to the remaining mixing angles.

   hep-phPRD(2016)·30 citations
4. 04*

   Dark Matter Annihilation Decay at The LHC

   Yuhsin Tsai🇺🇸 · Lian-Tao Wang🇺🇸 · Yue Zhao🇺🇸

   Collider experiments provide an opportunity to shed light on dark matter (DM) self-interactions. In this work, we study the possibility of generating DM bound states -- the Darkonium -- at the LHC and discuss how the annihilation decay of the Darkonium produces force carriers. We focus on two popular scenarios that contain large DM self-couplings: the Higgsinos in the $\lambda$-SUSY model, and self-interacting DM (SIDM) framework. After forming bound states, the DM particles annihilate into force mediators, which decay into the standard model particles either through a prompt or displaced process. This generates interesting signals for the heavy resonance search. We calculate the production rate of bound states and study the projected future constraints from the existing heavy resonance searches.

   hep-phhep-exPRD(2016)·24 citations
5. 05*

   Model independent constraints on four-lepton operators

   Adam Falkowski🇫🇷 · Kin Mimouni🇨🇭

   We obtain constraints on four-lepton interactions in the effective field theory with dimension-6 operators. To this end, we combine the experimental input from Z boson measurements in LEP-1, W boson mass and decays, muon and tau decays, lepton pair production in LEP-2, neutrino scattering on electrons, and parity violating electron scattering. The analysis does not rely on any assumptions about the flavor structure of the dimension-6 operators. Our main results are the confidence intervals for Wilson coefficients of 16 lepton-flavor conserving four-lepton operators, together with the full correlation matrix. Consequences for leptophilic models beyond the Standard Model are discussed.

   hep-phJHEP(2016)·96 citations
6. 06*

   R-Parity Violation and Light Neutralinos at SHiP and the LHC

   Jordy de Vries🇩🇪 · Herbi K. Dreiner🇩🇪 · Daniel Schmeier🇩🇪

   We study the sensitivity of the proposed SHiP experiment to the LQD operator in R-parity violating supersymmetric theories. We focus on single neutralino production via rare meson decays and the observation of downstream neutralino decays into charged mesons inside the SHiP decay chamber. We provide a generic list of effective operators and decay width formulae for any LQD coupling and show the resulting expected SHiP sensitivity for a widespread list of benchmark scenarios via numerical simulations. We compare this sensitivity to expected limits from testing the same decay topology at the LHC with ATLAS.

   hep-phPRD(2016)·47 citations
7. 07*

   Z' models for the LHCb and g-2 muon anomalies

   Ben Allanach🇬🇧 · Farinaldo S. Queiroz🇩🇪 · Alessandro Strumia🇮🇹 · Sichun Sun🇨🇳

   We revisit a class of Z' explanations of the anomalies found by the LHCb collaboration in $B$ decays, and show that the scenario is tightly constrained by a combination of constraints: (i) LHC searches for di-muon resonances, (ii) pertubativity of the Z' couplings; (iii) the $B_s$ mass difference, and (iv) and electro-weak precision data. Solutions are found by suppressing the Z' coupling to electrons and to light quarks and/or by allowing for a Z' decay width into dark matter. We also present a simplified framework where a TeV-scale Z' gauge boson that couples to standard leptons as well as to new heavy vector-like leptons, can simultaneously accommodate the LHCb anomalies and the muon g-2 anomaly.

   hep-phPRD(2016)·178 citations
8. 08*

   Diffractive Dijet Production in Deep Inelastic Scattering and Photon-Hadron Collisions in the Color Glass Condensate

   Tolga Altinoluk🇪🇸 · Néstor Armesto🇪🇸 · Guillaume Beuf🇮🇱 · Amir H. Rezaeian🇨🇱

   We study exclusive dijet production in coherent diffractive processes in deep inelastic scattering and real (and virtual) photon-hadron (${\gamma }^{(\ast )}$-h) collisions in the Color Glass Condensate formalism at leading order. We show that the diffractive dijet cross section is sensitive to the color-dipole orientation in the transverse plane, and is a good probe of possible correlations between the $q\bar{q}$-dipole transverse separation vector \r and the dipole impact parameter $\text{b}$. We also investigate the diffractive dijet azimuthal angle correlations and $t$-distributions in ${\gamma }^{(\ast )}$-h collisions and show that they are sensitive to gluon saturation effects in the small-$x$ region. In particular, we show that the $t$-distribution of diffractive dijet photo-production off a proton target exhibits a dip-type structure in the saturation region. This effect is similar to diffractive vector meson production. Besides, at variance with the inclusive case, the effect of saturation leads to stronger azimuthal correlations between the jets.

   hep-phhep-exnucl-thPLB(2016)·105 citations
9. 09*

   Verifiable Associated Processes from Radiative Lepton Masses with Dark Matter

   Sean Fraser🇺🇸 · Ernest Ma🇺🇸 · Mohammadreza Zakeri🇺🇸

   If leptons do not couple directly to the one Higgs doublet of the standard model of particle interactions, they must still do so somehow indirectly to acquire mass, as proposed recently in several models where it happens in one loop through dark matter. We analyze the important consequences of this scenario in a specific model, including Higgs decay, muon anomalous magnetic moment, $\mu \to e\gamma$, $\mu \to eee$, and the proposed dark sector.

   hep-phPRD(2016)·33 citations
10. 10*

    Signatures of top flavour-changing dark matter

    Jorgen D'Hondt🇧🇪 · Alberto Mariotti🇧🇪 · Kentarou Mawatari🇫🇷 · Seth Moortgat🇧🇪 · Pantelis Tziveloglou🇧🇪 · Gerrit Van Onsem🇧🇪

    We develop the phenomenology of scenarios in which a dark matter candidate interacts with a top quark through flavour-changing couplings, employing a simplified dark matter model with an s-channel vector-like mediator. We study in detail the top-charm flavour-changing interaction, by investigating the single top plus large missing energy signature at the LHC as well as constraints from the relic density and direct and indirect dark matter detection experiments. We present strategies to distinguish between the top-charm and top-up flavour-changing models by taking advantage of the lepton charge asymmetry as well as by using charm-tagging techniques on an extra jet. We also show the complementarity between the LHC and canonical dark matter experiments in exploring the viable parameter space of the models.

    hep-phJHEP(2016)·15 citations
11. 11*

    On the electric charge of the observable Universe

    Cody Goolsby-Cole🇺🇸 · Lorenzo Sorbo🇺🇸

    Light fields get large scale fluctuations during inflation. If some of them are electrically charged, then large scale fluctuations of the electric charge will be generated. As a consequence, any finite portion of the Universe, including our observable one, will carry a net electric charge. This fact does not require any form of breaking of the gauge symmetry at any time. We discuss under which conditions such a charge is maintained until the end of inflation, and we estimate its expected magnitude both in the case of charged fermions and of charged scalars. While one charged fermion species yields a charge density that is several orders of magnitude below the observational constraints, extremely light charged scalars can exceed those constraints.

    hep-phastro-ph.COhep-th7 citations
12. 12*

    The physics of antineutrinos in DUNE and determination of octant and ${\delta }_{CP}$

    Newton Nath🇮🇳 · Monojit Ghosh🇮🇳 · Srubabati Goswami🇮🇳

    The octant of ${\theta }_{23}$ and ${\delta }_{CP}$ are the two major unknowns in neutrino oscillation physics. The precise determination of octant and ${\delta }_{CP}$ is interlinked through the octant-${\delta }_{CP}$ degeneracy. In this paper we study the proficiency of the DUNE experiment to determine these parameters, in particular, the role played by the antineutrinos, the broadband nature of the beam and the matter effect. For $P_{\mu e}$ and $P_{\bar{\mu }\bar{e}}$ the octant-${\delta }_{CP}$ degeneracy occurs at different values of ${\delta }_{CP}$, combination of neutrino and antineutrino runs help to resolve this. However, in regions where neutrinos do not have octant degeneracy adding antineutrino data is expected to decrease the sensitivity because of the degeneracy and reduced statistics. However we find that in case of DUNE baseline, the antineutrino runs help even in parameter space where the antineutrino probabilities suffer from degeneracies. We explore this point in detail and point out that this happens because of the (i) broad-band nature of the beam so that even if there is degeneracy at a particular energy bin, over the whole spectrum the degeneracy may not be there; (ii) the enhanced matter effect due to the comparatively longer baseline which creates an increased tension between the neutrino and the antineutrino probabilities which raises the overall ${\chi }^2$ in case of combined runs. This feature is more prominent for IH since the antineutrino probabilities in this case are much higher than the neutrino probabilities due to matter effects. The main role of antineutrinos in enhancing CP sensitivity is their ability to remove the octant-${\delta }_{CP}$ degeneracy. However even if one assumes octant to be known the addition of antineutrinos can give enhanced CP sensitivity in some parameter regions due to the tension between the neutrino and antineutrino ${\chi }^2$s.

    hep-phNPB(2016)·51 citations
13. 13*

    Trail of the Higgs in the primordial spectrum

    Jinn-Ouk Gong🇰🇷 · Chengcheng Han🇯🇵 · Shi Pi🇰🇷

    We study the effects of the Higgs directly coupled to the inflaton on the primordial power spectrum. The quadratic coupling between the Higgs and the inflaton stabilizes the Higgs in the electroweak vacuum during inflation by inducing a large effective mass for the Higgs, which also leads to oscillatory features in the primordial power spectrum due to the oscillating classical background. Meanwhile, the features from quantum fluctuations exhibit simple monotonic k-dependence and are subleading compared to the classical contributions. We also comment on the collider searches.

    hep-phastro-ph.COgr-qc2 citations
14. 14*

    Strong-Field Breit-Wheeler Pair Production in Short Laser Pulses: Identifying Multiphoton Interference and Carrier-Envelope-Phase Effects

    Martin J. A. Jansen🇩🇪 · Carsten Müller🇩🇪

    The creation of electron-positron pairs by the strong-field Breit-Wheeler process in intense short laser pulses is investigated in the framework of laser-dressed quantum electrodynamics. Regarding laser field parameters in the multiphoton regime, special attention is brought to the energy spectrum of the created particles, which can be reproduced and explained by means of an intuitive model. The model is based on the probabilities of multiphoton events driven by the spectral components of the laser pulse. It allows, in particular, to identify interferences between different pair production channels which exhibit a characteristic dependence on the laser carrier-envelope phase.

    hep-phphysics.atom-phPRD(2016)·35 citations
15. 15*

    Bottom production in Photon and Pomeron -- induced interactions at the LHC

    V. P. Goncalves🇧🇷 · C. Potterat🇧🇷 · M. S. Rangel🇧🇷

    In this paper we present a detailed comparison of the bottom production in gluon -- gluon, photon -- gluon, photon -- photon, pomeron -- gluon, pomeron -- pomeron and pomeron -- photon interactions at the LHC. The transverse momentum, pseudo -- rapidity and $\xi$ dependencies of the cross sections are calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which allows to obtain realistic predictions for the bottom production with one or two leading intact protons. Moreover, predictions for the the kinematical range probed by the LHCb Collaboration are also presented. Our results indicate that the analysis of the single diffractive events is feasible using the Run I LHCb data.

    hep-phhep-exPRD(2016)·16 citations
16. 16*

    Leptons from heavy-quark semileptonic decay in pA collisions within the CGC framework

    Hirotsugu Fujii🇯🇵 · Kazuhiro Watanabe🇨🇳

    We study single lepton production from semileptonic decays of heavy flavor hadrons ($D,B\to l$) in pp and p$A$ collisions at RHIC and the LHC within the saturation/Color-Glass-Condensate (CGC) framework. Using the gluon distribution function obtained with the dipole amplitude, whose energy dependence is described by the Balitsky-Kovchegov equation with running coupling effect, we compute the transverse-momentum ($p_{\perp }$) spectra of the lepton yields at mid and forward rapidities. We find that a large fraction of leptons at low $p_{\perp }$ stems from the saturation regime of the incoming gluons in the target, especially in p$A$ collisions at the LHC. The resultant $p_{\perp }$ spectra is slightly harder than the data, but the nuclear modification factor seems consistent with the data within some uncertainty. We also update the nuclear modification factors for J/$\psi$ and $D$ meson at the LHC energy.

    hep-phnucl-thNPA(2016)·19 citations
17. 17*

    Improved effective vector boson approximation revisited

    Werner Bernreuther🇩🇪 · Long Chen🇩🇪

    We reexamine the improved effective vector boson approximation which is based on two-vector-boson luminosities ${\mathbf{L}}_{\mathrm{pol}}$ for the computation of weak gauge-boson hard scattering subprocesses $V_1{V}_2\to \mathcal{W}$ in high-energy hadron-hadron or $e^{-}{e}^{+}$ collisions. We calculate these luminosities for the nine combinations of the transverse and longitudinal polarizations of $V_1$ and $V_2$ in the unitary and axial gauge. For these two gauge choices the quality of this approach is investigated for the reactions $e^{-}{e}^{+}\to W^{-}{W}^{+}{\nu }_e{\bar{\nu }}_e$ and $e^{-}{e}^{+}\to t\bar{t}{\nu }_e{\bar{\nu }}_e$ using appropriate phase-space cuts.

    hep-phPRD(2016)·9 citations
18. 18*

    Freeze-in production of Fermionic Dark Matter with Pseudo-scalar and Phenomenological Aspects

    Seyed Yaser Ayazi🇮🇷 · S. Mahdi Firouzabadi🇮🇷 · S. Peyman Zakeri🇮🇷

    In this paper, we study freeze-in production of fermionic dark matter with a pseudo scalar as the mediator between dark sector and Standard Model (SM). While the fermionic DM is non-thermal, we will explain two scenarios in which production of pseudo-scalar particles are either thermal or non thermal. We'll present elaborate discussion to derive yield quantity and relic density and illustrate these values for the different range of model parameters. We'll investigate constraints on parameters space coming from invisible Higgs decay at LHC. For the case of extremely small couplings and zero mixing between SM Higgs field with pseudo scalar field which pseudo scalar boson can play role of DM, we will justify recent observation of merging galaxies with a case of self-interacting DM. We'll show that influence of DM annihilation in this case, would provide a better fit to the AMS-02 data of positron flux.

    hep-phJ.Phys.G(2016)·22 citations
19. 19*

    Complex Masses of Resonances in the Potential Approach

    M.N. Sergeenko🇧🇾

    Quarkonium resonances in the complex-mass scale are studied. Relativistic quark potential model is used to describe the quark-antiquark system. The complex-mass formula is obtained from two exact asymptotic solutions for the QCD motivated potential with the distance-dependent value of the strong coupling in QCD. The centered masses and total widths of some meson resonances are calculated. A possible origin of the ``dark matter'' and the ``Missing Mass''is discussed.

    hep-phNonlin. Phen. Compl. Syst. 17 (2014) 433-…·1 citation
20. 20*

    Dual representation for the generating functional of the Feynman path-integral

    Marco Matone🇮🇹

    The generating functional for scalar theories admits a representation which is dual with respect to the one introduced by Schwinger, interchanging the role of the free and interacting terms. It maps $\int V({\delta }_J)$ and $J\Delta J$ to ${\delta }_{{\varphi }_c}\Delta {\delta }_{{\varphi }_c}$ and $\int V({\varphi }_c)$, respectively, with ${\varphi }_c=\int J\Delta$ and $\Delta$ the Feynman propagator. Comparing the Schwinger representation with its dual version one gets a little known relation that we prove to be a particular case of a more general operatorial relation. We then derive a new representation of the generating functional $T[{\varphi }_c]=W[J]$ expressed in terms of covariant derivatives acting on 1 $$T[{\varphi }_c]=\frac{N}{N_0}\exp (-U_0[{\varphi }_c])\exp (-\int V({\mathcal{D}}_{{\varphi }_c}^{-}))\cdot 1$$ where ${\mathcal{D}}_{\varphi }^{\pm }(x)=\mp \Delta \frac{\delta }{\delta \varphi }(x)+\varphi (x)$. The dual representation, which is deeply related to the Hermite polynomials, is the key to express the generating functional associated to a sum of potentials in terms of factorized generating functionals. This is applied to renormalization, leading to a factorization of the counterterms of the interaction. We investigate the structure of the functional generator for normal ordered potentials and derive an infinite set of relations in the case of the potential $\frac{\lambda }{n!}:{\varphi }^n:$. Such relations are explicitly derived by using the Faà di Bruno formula. This also yields the explicit expression of the generating functional of connected Green's functions.

    ↳ hep-thcond-mat.stat-mechhep-phmath-ph+2NPB(2016)·4 citations
21. 21*

    Infinite-Dimensional Fermionic Symmetry in Supersymmetric Gauge Theories

    Thomas T. Dumitrescu🇺🇸 · Temple He🇺🇸 · Prahar Mitra🇺🇸 · Andrew Strominger🇺🇸

    We establish the existence of an infinite-dimensional fermionic symmetry in four-dimensional supersymmetric gauge theories by analyzing semiclassical photino dynamics in abelian $\mathcal{N}=1$ theories with charged matter. The symmetry is parametrized by a spinor-valued function on an asymptotic $S^2$ at null infinity. It is not manifest at the level of the Lagrangian, but acts non-trivially on physical states, and its Ward identity is the soft photino theorem. The infinite-dimensional fermionic symmetry resides in the same $\mathcal{N}=1$ supermultiplet as the physically non-trivial large gauge symmetries associated with the soft photon theorem.

    ↳ hep-thhep-phJHEP(2021)·92 citations
22. 22*

    Probing a panoply of curvaton-decay scenarios using CMB data

    Tristan L. Smith (Swarthmore College)🇺🇸 · Daniel Grin (University of Chicago)🇺🇸

    In the curvaton scenario, primordial curvature perturbations are produced by a second field that is sub-dominant during inflation. Depending on how the curvaton decays [possibly producing baryon number, lepton number, or cold dark matter (CDM)], mixtures of correlated isocurvature perturbations are produced, allowing the curvaton scenario to be tested using cosmic microwave background (CMB) data. Here, a full range of 27 curvaton-decay scenarios is compared with CMB data, placing limits on the curvaton fraction at decay, $r_D$, and the lepton asymmetry, ${\xi }_{\mathrm{lep}}$. If baryon number is generated by curvaton decay and CDM before (or vice-versa), these limits imply specific predictions for non-Gaussian signatures testable by future CMB experiments and upcoming large-scale-structure surveys.

    ↳ astro-ph.COgr-qchep-phPRD(2016)·17 citations
23. 23*

    On the Evolution of Jet Energy and Opening Angle in Strongly Coupled Plasma

    Paul M. Chesler🇺🇸 · Krishna Rajagopal🇺🇸

    We calculate how the energy and the opening angle of jets in $\mathcal{N}=4$ SYM theory evolve as they propagate through the strongly coupled plasma of that theory. We define the rate of energy loss $d{E}_{\mathrm{jet}}/dx$ and the jet opening angle in a straightforward fashion directly in the gauge theory before calculating both holographically, in the dual gravitational description. In this way, we rederive the previously known result for $d{E}_{\mathrm{jet}}/dx$ without the need to introduce a finite slab of plasma. We obtain a striking relationship between the initial opening angle of the jet, which is to say the opening angle that it would have had if it had found itself in vacuum instead of in plasma, and the thermalization distance of the jet. Via this relationship, we show that $\mathcal{N}=4$ SYM jets with any initial energy that have the same initial opening angle and the same trajectory through the plasma experience the same fractional energy loss. We also provide an expansion that describes how the opening angle of the $\mathcal{N}=4$ SYM jets increases slowly as they lose energy, over the fraction of their lifetime when their fractional energy loss is not yet large. We close by looking ahead toward potential qualitative lessons from our results for QCD jets produced in heavy collisions and propagating through quark-gluon plasma.

    ↳ hep-thhep-phnucl-thJHEP(2016)·64 citations
24. 24*

    f(T) teleparallel gravity and cosmology

    Yi-Fu Cai🇨🇳 · Salvatore Capozziello🇮🇹 · Mariafelicia De Laurentis🇩🇪 · Emmanuel N. Saridakis🇬🇷

    Over the past decades, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description. Here we review various torsional constructions, from teleparallel, to Einstein-Cartan, and metric-affine gauge theories, resulting in extending torsional gravity in the paradigm of f(T) gravity, where f(T) is an arbitrary function of the torsion scalar. Based on this theory, we further review the corresponding cosmological and astrophysical applications. In particular, we study cosmological solutions arising from f(T) gravity, both at the background and perturbation levels, in different eras along the cosmic expansion. The f(T) gravity construction can provide a theoretical interpretation of the late-time universe acceleration, and it can easily accommodate with the regular thermal expanding history including the radiation and cold dark matter dominated phases. Furthermore, if one traces back to very early times, a sufficiently long period of inflation can be achieved and hence can be investigated by cosmic microwave background observations, or alternatively, the Big Bang singularity can be avoided due to the appearance of non-singular bounces. Various observational constraints, especially the bounds coming from the large-scale structure data in the case of f(T) cosmology, as well as the behavior of gravitational waves, are described in detail. Moreover, the spherically symmetric and black hole solutions of the theory are reviewed. Additionally, we discuss various extensions of the f(T) paradigm. Finally, we consider the relation with other modified gravitational theories, such as those based on curvature, like f(R) gravity, trying to enlighten the subject of which formulation might be more suitable for quantization ventures and cosmological applications.

    ↳ gr-qcastro-ph.COhep-phhep-thRept.Prog.Phys.(2016)·1662 citations
25. 25*

    Holographic thermalization with initial long range correlation

    Shu Lin🇺🇸

    We studied the evolution of Wightman correlator in a thermalizing state modeled by AdS_3-Vaidya background. We gave a prescription for calculating Wightman correlator in coordinate space without using any approximation. For equal-time correlator $⟨O(v,x)O(v,0)⟩$, we obtained an enhancement factor $v^2$ due to long range correlation present in the initial state. This was missed by previous studies based on geodesic approximation. We found that the long range correlation in initial state does not lead to significant modification to thermalization time as compared to known results with generic initial state. We also studied spatially integrated Wightman correlator and showed evidence on the distinction between long distance and small momentum physics for an out-of-equilibrium state. We also calculated radiation spectrum of particle weakly coupled to $O$ and found lower frequency mode approaches thermal spectrum faster than high frequency mode.

    ↳ hep-thhep-phnucl-thPRD(2016)·4 citations
26. 26*

    Two-loop study of the deconfinement transition in Yang-Mills theories: SU(3) and beyond

    U. Reinosa🇫🇷 · J. Serreau🇫🇷 · M. Tissier🇫🇷 · N. Wschebor🇺🇾

    We study the confinement-deconfinement phase transition of pure Yang-Mills theories at finite temperature using a simple massive extension of standard background field methods. We generalize our recent next-to-leading-order perturbative calculation of the Polyakov loop and of the related background field effective potential for the SU(2) theory to any compact and connex Lie group with a simple Lie algebra. We discuss in detail the SU(3) theory, where the two-loop corrections yield improved values for the first-order transition temperature as compared to the one-loop result. We also show that certain one-loop artifacts of thermodynamical observables disappear at two-loop order, as was already the case for the SU(2) theory. In particular, the entropy and the pressure are positive for all temperatures. Finally, we discuss the groups SU(4) and Sp(2) which shed interesting light, respectively, on the relation between the (de)confinement of static matter sources in the various representations of the gauge group and on the use of the background field itself as an order parameter for confinement. In both cases, we obtain first-order transitions, in agreement with lattice simulations and other continuum approaches.

    ↳ hep-thhep-lathep-phnucl-thPRD(2016)·69 citations
27. 27*

    Recent developments in the theory of electromagnetic probes in relativistic heavy-ion collisions

    Chun Shen (McGill U.)🇨🇦

    The theoretical developments in the study of electromagnetic radiation in relativistic heavy-ion collisions are reviewed. The recent progress in the rates for photon and lepton pair production is discussed. Together with the improvements in the hydrodynamic descriptions of the bulk medium, the combined effort is discussed to resolve the "direct photon flow puzzle" in the RHIC and the LHC experiments. Further prediction of the direct photon production in high multiplicity proton-nucleus collisions at the LHC energy can serve as a signature of the quark gluon plasma formation in these small systems. Phenomenological study of dilepton production at finite net baryon density is highlighted at the collision energies available for the RHIC beam energy scan program.

    ↳ nucl-thhep-phnucl-exNucl.Part.Phys.Proc.(2016)·14 citations
28. 28*

    The Gamma Factory proposal for CERN

    Mieczyslaw Witold Krasny🇫🇷

    This year, 2015, marks the centenary of the publication of Einsteins Theory of General Relativity and it has been named the International Year of Light and light-based technologies by the UN General Assembly. It is thus timely to discuss the possibility of broadening the present CERN research program by including a new component based on a novel concept of the light source which could pave a way towards a multipurpose Gamma Factory. The proposed light source could be realized at CERN by using the infrastructure of the existing accelerators. It could push the intensity limits of the presently operating light-sources by at least 7 orders of magnitude, reaching the flux of the order of 10^17 photons/s, in the particularly interesting gamma-ray energy domain of 1 < Ephoton < 400 MeV. This domain is out of reach for the FEL-based light sources. The energy-tuned, quasi-monochromatic gamma beams, together with the gamma-beam-driven, high intensity secondary beams of polarized positrons, polarized muons, neutrons and radioactive ions would constitute the basic research tools of the proposed Gamma Factory. The Gamma Factory could open new research opportunities in a vast domain of uncharted fundamental physics and industrial application territories. It could strengthen the leading role of CERN in the high energy frontier research territory by providing the unprecedented-brilliance secondary beams of polarized muons for the TeV-energy-scale muon collider and the polarized- muon-beam based neutrino factory.

    ↳ hep-exhep-phphysics.acc-ph85 citations
29. 29*

    Galileon Higgs Vortices

    Javier Chagoya🇲🇽 · Gianmassimo Tasinato🇬🇧

    Vortex solutions are topologically stable field configurations that can play an important role in condensed matter, field theory, and cosmology. We investigate vortex configuration in a 2+1 dimensional Abelian Higgs theory supplemented by higher order derivative self-interactions, related with Galileons. Our vortex solutions have features that make them qualitatively different from well-known Abrikosov-Nielsen-Olesen configurations, since the derivative interactions turn on gauge invariant field profiles that break axial symmetry. By promoting the system to a 3+1 dimensional string configuration, we study its gravitational backreaction. Our results are all derived within a specific, analytically manageable system, and might offer indications for understanding Galileonic interactions and screening mechanisms around configurations that are not spherically symmetric, but only at most cylindrically symmetric.

    ↳ hep-thgr-qchep-phJHEP(2016)·9 citations
30. 30*

    Effective Low-Energy Potential for Slow Dirac Fermions in Einstein-Cartan Gravity with Torsion and Chameleon

    A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹

    We derive the most general effective low-energy potential to order O(1/m) for slow Dirac fermions with mass m, coupled to gravitational, chameleon and torsion fields in the Einstein-Cartan gravity. The obtained results can be applied to the experimental analysis of gravitational, chameleon and torsion interactions in terrestrial laboratories. We discuss the use of rotating coordinate systems, caused by rotations of devices, for measurements of the torsion vector and tensor components, caused by minimal torsion--fermion couplings (Ivanov and Wellenzohn, Phys. Rev. D92, 065006 (2015)). Using the most general form of a metric tensor of curved spacetimes in rotating coordinate systems, proposed by Obukhov, Silenko, and Teryaev (Phys. Rev. D84, 024025 (2011)), we extend this metric by the inclusion of the chameleon field and calculate the set of vierbein fields, in terms of which Dirac fermions couple to torsion vector and tensor components through minimal torsion-fermion couplings. For such a set of vierbein fields we discuss a part of the effective low-energy potential for slow Dirac fermions, coupled to gravitational, chameleon and torsion fields to order O(1) in the large fermion mass expansion.

    ↳ gr-qchep-phPRD(2015)·6 citations

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