Tue·Jun 22, 2021Tuesday·June 22, 2021

1. 01*

   The photon PDF within the CT18 global analysis

   Keping Xie🇺🇸 · T. J. Hobbs🇺🇸 · Tie-Jiun Hou🇨🇳 · Carl Schmidt🇺🇸 · Mengshi Yan🇨🇳 · C.-P. Yuan🇺🇸

   Building upon the most recent CT18 global fit, we present a new calculation of the photon content of the proton based on an application of the LUX formalism. In this work, we explore two principal variations of the LUX ansatz. In one approach, which we designate "CT18lux," the photon PDF is calculated directly using the LUX formula for all scales, $\mu$. In an alternative realization, "CT18qed," we instead initialize the photon PDF in terms of the LUX formulation at a lower scale, $\mu \sim {\mu }_0$, and evolve to higher scales with a combined QED+QCD kernel at $\mathcal{O}(\alpha ),\mathcal{O}(\alpha {\alpha }_s)$ and $\mathcal{O}({\alpha }^2)$. While we find these two approaches generally agree, especially at intermediate $x$ ($10^{-3}\lesssim x\lesssim 0.3$), we discuss some moderate discrepancies that can occur toward the end-point regions at very high or low $x$. We also study effects that follow from variations of the inputs to the LUX calculation originating outside the pure deeply-inelastic scattering (DIS) region, including from elastic form factors and other contributions to the photon PDF. Finally, we investigate the phenomenological implications of these photon PDFs for the LHC, including high-mass Drell-Yan, vector-boson pair, top-quark pair, and Higgs associated with vector-boson production.

   hep-phhep-exnucl-thPRD(2022)·55 citations
2. 02*

   Feeble DM-SM Interaction via New Scalar and Vector Mediators in Rotating Neutron Stars

   Atanu Guha🇮🇳 · Debashree Sen🇮🇳

   We investigate the possible presence of dark matter (DM) in massive and rotating neutron stars (NSs). For the purpose we extend our previous work [1] to introduce a light new physics vector mediator besides a scalar one in order to ensure feeble interaction between fermionic DM and $\beta$ stable hadronic matter in NSs. The masses of DM fermion, the mediators and the couplings are chosen consistent with the self-interaction constraint from Bullet cluster and from present day relic abundance. Assuming that both the scalar and vector mediators contribute equally to the relic abundance, we compute the equation of state (EoS) of the DM admixed NSs to find that the present consideration of the vector new physics mediator do not bring any significant change to the EoS and static NS properties of DM admixed NSs compared to the case where only the scalar mediator was considered [1]. However, the obtained structural properties in static conditions are in good agreement with the various constraints on them from massive pulsars like PSR J0348+0432 and PSR J0740+6620, the gravitational wave (GW170817) data and the recently obtained results of NICER experiments for PSR J0030+0451 and PSR J0740+6620. We also extended our work to compute the rotational properties of DM admixed NSs rotating at different angular velocities. The present results in this regard suggest that the secondary component of GW190814 may be a rapidly rotating massive DM admixed NS. The constraints on rotational frequency from pulsars like PSR B1937+21 and PSR J1748-2446ad are also satisfied by our present results. Also, the constraints on moment of inertia are satisfied considering slow rotation. The universality relation in terms of normalized moment of inertia also holds good with our DM admixed EoS.

   hep-phastro-ph.COastro-ph.HEnucl-thJCAP(2021)·39 citations
3. 03*

   A Radiative Neutrino Mass Model in Dark Non-Abelian Gauge Symmetry

   Takaaki Nomura🇨🇳 · Hiroshi Okada🇰🇷

   We discuss a model based on dark sector described by non-Abelian $SU(2{)}_D$ gauge symmetry where we introduce $SU(2{)}_L\times SU(2{)}_D$ bi-doublet vector-like leptons to generate active neutrino masses and kinetic mixing between $SU(2{)}_D$ and $U(1{)}_Y$ gauge fields at one-loop level. After spontaneous symmetry breaking of $SU(2{)}_D$, we have remnant $Z_4$ symmetry guaranteeing stability of dark matter candidates. We formulate neutrino mass matrix and related lepton flavor violating processes and discus dark matter physics estimating relic density. It is found that our model realize multicomponent dark matter scenario due to the $Z_4$ symmetry and relic density can be explained by gauge interactions with kinetic mixing effect.

   hep-phPRD(2022)·11 citations
4. 04*

   Is two-poles' $\Lambda (1405)$ one state or two?

   Zhong-Yu Wang🇨🇳 · Hiwa A. Ahmed🇨🇳 · C. W. Xiao🇨🇳

   To understand the nature of two poles for the $\Lambda (1405)$ state, we revisit the interactions of $\bar{K}N$ and $\pi \Sigma$ with their coupled channels, where two-poles structure is found in the second Riemann sheet. We also dynamically generate two poles in the single channel interaction of $\bar{K}N$ and $\pi \Sigma$, respectively. Moreover, we make a further study of two poles' properties by evaluating the couplings, the compositeness, the wave functions, and the radii for the interactions of four coupled channels, two coupled channels and the single channel. Our results show that the nature of two poles is unique. The higher-mass pole is a pure $\bar{K}N$ molecule, and the lower-mass one is a compositeness of mainly $\pi \Sigma$ with tiny component $\bar{K}N$. From our results, one can conclude that the $\Lambda (1405)$ state would be overlapped with two different states of the same quantum number.

   hep-phnucl-thEPJC(2021)·11 citations
5. 05*

   Study of $N(1440)$ structure via ${\gamma }^{\ast }p\to N(1440)$ transition

   A. Kaewsnod🇹🇭 · K. Xu🇹🇭 · Z. Zhao🇹🇭 · X. Y. Liu🇹🇭 · S. Srisuphaphon🇹🇭 · A. Limphirat🇹🇭 · Y. Yan🇹🇭

   We study the photoproduction of the $N(1440)$ resonance in ${\gamma }^{\ast }p\to N^{\ast }$ process in quark models, where the $N(1440)$ takes different wave functions: first radial excitation of the nucleon imported from low-lying baryon mass spectrum calculations, a general radial excitation of the nucleon, and a $q^3$ state with positive parity. The comparison between the theoretical results and experimental data on the helicity amplitudes $A_{1/2}$ and $S_{1/2}$ and the analysis of the spatial wave function of the $N(1440)$ resonance reveal that the $N(1440)$ resonance is mainly the $q^3$ first radial excitation.

   hep-phnucl-thPRD(2022)·6 citations
6. 06*

   W exchange contributions in hadronic decays of charmed baryons

   Fayyazuddin🇵🇰

   The nonleptonic decays of ${\Xi }_c^0$ and ${\Lambda }_c^{+}$ that are dominated by $W$-exchange are studied. In particular, we anlayse the decay modes ${\Xi }_c^0\to {\Xi }^{\ast -}{\pi }^{+},{\Sigma }^{\ast +}{K}^{-},{\Omega }^{-}{K}^{+}$ and ${\Lambda }_c^{+}\to {\Sigma }^0{\pi }^{+},{\Xi }^0{K}^{+}$, ${\Xi }_c^0\to {\Sigma }^{+}{K}^{-}$.

   hep-ph0 citations
7. 07*

   Searching for possible evidences of new physics in $B\to V_1{V}_2$

   C.Q. Geng🇨🇳 · Chia-Wei Liu🇨🇳

   We explore the decays of $B\to V_1{V}_2$ ($V_{1,2}=(\rho ,\omega ,K^{\ast },\varphi )$ and $B=(B^0,B^{+},B_s)$) with transverse polarizations. We explicitly evaluate the eigenstates of T-odd scalar operators involving spins for the first time, which offer physical insight among the T violating observables. Based on the helicity suppression of tree operators for transverse polarizations in the standard model (SM), we deduce that $\Delta {\varphi }_p=\Delta {\varphi }_{\parallel }-\Delta {\varphi }_{\perp }=0$ with $\Delta {\varphi }_{\perp ,\parallel }$ the weak phases of the transverse amplitudes. In contrast, the experiments show that $\Delta {\varphi }_p(B^0\to K^{\ast 0}\omega )=-0.84\pm 0.54$, which could be a signal of new physics. There is also a discrepancy between our result in the SM and the experimental data for the transverse polarized branching ratio in $B^0\to K^{\ast 0}\omega$. In addition, by counting the helicity flips, we argue that $\sin ({\varphi }_{\parallel }-{\varphi }_{\perp })\approx 0$, which meets well with most of the experiments except for the ones with $B^0\to K^{\ast 0}\omega$, where ${\varphi }_{\parallel ,\perp }$ are the strong phases in the transverse amplitudes.

   hep-phhep-exPLB(2022)·8 citations
8. 08*

   Semileptonic decays $D\to \eta \pi e^{+}{\nu }_e$ in the $a_0(980)$ region

   N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺 · G.N. Shestakov🇷🇺

   The mechanism of the four-quark production of the light scalar isovector four-quark state $a_0(980)$ in the $D\to \eta \pi e^{+}{\nu }_e$ decays is discussed. It is shown that the characteristic features of the shape of the $\eta \pi$ mass spectra expected in our scheme can serve as the indicator of the production mechanism and internal structure of the $a_0(980)$ resonance.

   hep-phhep-exnucl-thPRD(2021)·13 citations
9. 09*

   Spectra of glueballs and oddballs and the equation of state from holographic QCD

   Lin Zhang🇨🇳 · Chutian Chen🇨🇳 · Yidian Chen🇨🇳 · Mei Huang🇨🇳

   We study the spectra of two-gluon glueballs and three-gluon oddballs and corresponding equation of state in $5$-dimensional deformed holographic QCD models in the graviton-dilaton system, where the metric, the dilaton field and dilaton potential are self-consistently solved from each other through the Einstein field equations and the equation of motion of the dilaton field. We compare the models by inputting the dilaton field, inputting the deformed metric and inputting the dilaton potential, and find that with only 2 parameters, the $5$-dimensional holographic QCD model predictions on glueballs/oddballs spectra in general are in good agreement with lattice results except two oddballs $0^{+-}$ and $2^{+-}$. From the results of glueballs/oddballs spectra at zero temperature and the equation of state at finite temperature, we observe that the model with quadratic dilaton field can simultaneously describe glueballs/oddballs spectra as well as equation of state of pure gluon system. The model with quadratic $A_E(z)$ can describe glueballs/oddballs spectra, but its corresponding equation of state behaves more like $N_f=2+1$ quark matter. These are consistent with dimension analysis at UV boundary.

   hep-phPRD(2022)·27 citations
10. 10*

    nonlocal quark condensate from Dyson-Schwinger Equation and its contributions to the gluon vacuum polarization based on OPE approach

    Jing-Hui Huang🇨🇳 · Xue-Ying Duan🇨🇳 · Chen Huan🇨🇳 · Guang-Jun Wang🇨🇳 · Xiang-Yun Hu🇨🇳

    The operator-product expansion(OPE) could be employed to obtain the lowest-order, nonlocal quark scalar condensate component of gluon vacuum polarization. In particular, nonlocal quark scalar condensate can be calculated by solving Dyson-Schwinger Equation(DSE) of QCD. Then, field-theoretic aspects of the gluon vacuum polarization and nonperturbative gluon propagator will be considered in the Landau gauge of the Lorentz gauge fixing. The gluon propagator we obtained is finite in the infrared domain where the single gluon mass $m_g$ can be determined. Our results of the ratio $m_g/{\Lambda }_{QCD}$ the range of that from 1.33 to 1.39 agree with previous determinations for this ratio. Besides, the analytic structure of the gluon propagators from the OPE's result is explored. Our numerical analysis of the gluon' Schwinger function finds clear evidence of the positivity violations in the gluon propagator. In addition, a new method for obtaining the chemical potential dependence of the gluon vacuum polarization and the dressed gluon propagator is developed.

    hep-phMod.Phys.Lett.A(2022)·0 citations
11. 11*

    TeV-scale Lepton Number Violation: Connecting Leptogenesis, Neutrinoless Double Beta Decay, and Colliders

    Julia Harz🇩🇪 · Michael J. Ramsey-Musolf🇨🇳 · Tianyang Shen🇺🇸 · Sebastián Urrutia Quiroga🇺🇸

    In the context of TeV-scale lepton number violating (LNV) interactions, we illustrate the interplay between leptogenesis, neutrinoless double beta ($0\nu \beta \beta$) decay, and LNV searches at proton-proton colliders. Using a concrete model for illustration, we identify the parameter space where standard thermal leptogenesis is rendered unviable due to washout processes and show how $0\nu \beta \beta$ decay and $pp$ collisions provide complementary probes. We find that the new particle spectrum can have a decisive impact on the relative sensitivity of these two probes.

    hep-phPRD(2024)·24 citations
12. 12*

    Accessing Topological Fluctuations of Gauge Fields with Chiral Magnetic Effect

    Anping Huang🇨🇳 · Shuzhe Shi🇨🇦 · Shu Lin🇨🇳 · Xingyu Guo🇨🇳 · Jinfeng Liao🇺🇸

    Gauge fields provide the fundamental interactions in the Standard Model of particle physics. Gauge field configurations with nontrivial topological windings are known to play crucial roles in many important phenomena, from matter-anti-matter asymmetry of today's universe to spontaneous chiral symmetry breaking in strong interaction. Their presence is however elusive for direct detection in experiments. Here we show that measurements of the chiral magnetic effect (CME) in heavy ion collisions can be used for accessing the topological fluctuations of the non-Abelian gauge fields in the Quantum Chromodynamics (QCD). To achieve this, we implemented a key ingredient, the stochastic dynamics of gauge field topological fluctuations, into a state-of-the-art framework for simulating the CME in these collisions. This new framework provides the necessary tool to quantify initial topological fluctuations from any definitive CME signal to be extracted from experimental data. It also reveals a universal scaling relation between initial topological fluctuations and particle multiplicity produced in the corresponding collision events.

    hep-phhep-thnucl-exnucl-thPRD(2023)·3 citations
13. 13*

    Mixing of X and Y states from QCD Sum Rules analysis

    Ze-Sheng Chen🇨🇳 · Zhuo-Ran Huang🇨🇳 · Hong-Ying Jin🇨🇳 · T.G. Steele🇨🇦 · Zhu-Feng Zhang🇨🇳

    We study $\bar{Q}Q\bar{q}q$ and $\bar{Q}qQ\bar{q}$ states as mixed states in QCD sum rules. By calculating the two-point correlation functions of pure states of their corresponding currents, we review the mass and coupling constant predictions of $J^{PC}=1^{++}$, $1^{--}$, $1^{-+}$ states. By calculating the two-point mixed correlation functions of $\bar{Q}Q\bar{q}q$ and $\bar{Q}qQ\bar{q}$ currents, and we estimate the mass and coupling constants of the corresponding `"physical state" that couples to both $\bar{Q}Q\bar{q}q$ and $\bar{Q}qQ\bar{q}$ currents. Our results suggest that $1^{++}$ states are more likely mixing from $\bar{Q}Q\bar{q}q$ and $\bar{Q}qQ\bar{q}$ components, while for $1^{--}$ and $1^{-+}$ states, there is less mixing between $\bar{Q}Q\bar{q}q$ and $\bar{Q}qQ\bar{q}$. Our results suggest the $Y$ series of states have more complicated components.

    hep-phCPC(2022)·3 citations
14. 14*

    Electron EDM arising from modulus $\tau$ in the supersymmetric modular invariant flavor models

    Morimitsu Tanimoto🇯🇵 · Kei Yamamoto🇯🇵

    The electric dipole moment (EDM) of electron is studied in the supersymmetric ${\mathrm{A}}_4$ modular invariant theory of flavors with CP invariance. The CP symmetry of the lepton sector is broken by fixing the modulus $\tau$. Lepton mass matrices are completely consistent with observed lepton masses and mixing angles in our model. In this framework, a fixed $\tau$ also causes the CP violation in the soft SUSY breaking terms. The elecrton EDM arises from the CP non-conserved soft SUSY breaking terms. The experimental upper bound of the electron EDM excludes the SUSY mass scale below $2-6$ TeV for five cases of the lepton mass matrices. In order to see the effect of CP phase of the modulus $\tau$, we examine the correlation between the electron EDM and the decay rate of the $\mu \to e\gamma$ decay, which is also predicted by the soft SUSY breaking terms. The correlations are clearly predicted in contrast to models of the conventional flavor symmetry. The SUSY mass scale will be constrained by the future sensitivity of the electron EDM, $|d_e/e|\simeq 10^{-30}$. Indeed, it could probe the SUSY mass range of $10-20$ TeV in our model. Thus, the electron EDM provides a severe test of the CP violation via the modulus $\tau$ in the supersymmetric modular invariant theory of flavors.

    hep-phJHEP(2021)·25 citations
15. 15*

    A deuterated liquid scintillator for supernova neutrino detection

    Bhavesh Chauhan🇮🇳 · Basudeb Dasgupta🇮🇳 · Vivek Datar🇮🇳

    For the next galactic supernova, operational neutrino telescopes will measure the neutrino flux several hours before their optical counterparts. Existing detectors, relying mostly on charged current interactions, are mostly sensitive to ${\bar{\nu }}_e$ and to a lesser extent to ${\nu }_e$. In order to measure the flux of other flavors (${\nu }_{\mu },{\bar{\nu }}_{\mu },{\nu }_{\tau },\text{and}{\bar{\nu }}_{\tau }$), we need to observe their neutral current interactions with the detector. Such a measurement is not only crucial for overall normalization of the supernova neutrino flux but also for understanding the intricate neutrino oscillation physics. A deuterium based detector will be sensitive to all neutrino flavors. In this paper, we propose a 1 kton deuterated liquid scintillator (DLS) based detector that will see about 435 neutral current events and 170 (108) charged current ${\nu }_e$ (${\bar{\nu }}_e$) events from a fiducial supernova at a distance of 10 kpc from Earth. We explore the possibility of extracting spectral information from the neutral current channel $\stackrel{(-)}{\nu }d\to \stackrel{(-)}{\nu }np$ by measuring the quenched kinetic energy of the proton in the final state, where the neutron in the final state is tagged and used to reduce backgrounds. We also discuss the secondary interactions of the recoil neutrons in the detector.

    hep-phastro-ph.SRhep-exJCAP(2021)·8 citations
16. 16*

    Transverse charge distributions of the nucleon and their Abel images

    June-Young Kim🇩🇪 · Hyun-Chul Kim🇰🇷

    We investigate the two-dimensional transverse charge distributions of the transversely polarized nucleon. As the longitudinal momentum ($P_z$) of the nucleon increases, the electric dipole moment is induced, which causes the displacement of the transverse charge and magnetization distributions of the nucleon. The induced dipole moment of the proton reaches its maximum value at around $P_z\approx 3.2$ GeV due to the kinematical reason. We also investigate how the Abel transformations map the three-dimensional charge and magnetization distributions in the Breit frame on to the transverse charge and magnetization ones in the infinite momentum frame.

    hep-phhep-exhep-latPRD(2021)·22 citations
17. 17*

    A Study of QCD Radiation in VBF Higgs Production with Vincia and Pythia

    Stefan Höche🇺🇸 · Stephen Mrenna🇺🇸 · Shay Payne🇦🇺 · Christian T Preuss🇦🇺 · Peter Skands🇦🇺

    We discuss and illustrate the properties of several parton-shower algorithms available in Pythia and Vincia, in the context of Higgs production via vector boson fusion (VBF). In particular, the distinctive colour topology of VBF processes allows to define observables sensitive to the coherent radiation pattern of additional jets. We study a set of such observables, using the Vincia sector-antenna shower as our main reference, and contrast it to Pythia's transverse-momentum-ordered DGLAP shower as well as Pythia's dipole-improved shower. We then investigate the robustness of these predictions as successive levels of higher-order perturbative matrix elements are incorporated, including next-to-leading-order matched and tree-level merged calculations, using Powheg Box and Sherpa respectively to generate the hard events.

    hep-phhep-exSciPost Phys.(2022)·71 citations
18. 18*

    Strong decays of the low-lying doubly bottom baryons

    Hui-Zhen He🇨🇳 · Wei Liang🇨🇳 · Qi-Fang Lü🇨🇳

    In this work, we adopt the ${}^3{P}_0$ model to investigate the strong decays of the low-lying doubly bottom baryons in the $j-j$ coupling scheme systematically. In this scheme, we construct the formulism of ${}^3{P}_0$ model under the spectator assumption, and then the heavy diquark symmetry is preserved automatically. Our results show that some of the $\lambda$-mode ${\Xi }_{bb}(1P)$ and ${\Omega }_{bb}(1P)$ states are narrow, which have good potentials to be observed by future experiments. For the low-lying $\rho$-mode and $\rho$-$\lambda$ hybrid states, the Okubo-Zweig-Iizuka-allowed strong decays are highly suppressed and they should be extremely narrow. Future experiments can test our phenomenological predictions at the quark level.

    hep-phhep-exnucl-thPRD(2022)·12 citations
19. 19*

    Gravitational waves from the phase transition in the B-LSSM

    Xing-Xing Dong🇨🇳 · Tai-Fu Feng🇨🇳 · Hai-Bin Zhang🇨🇳 · Shu-Min Zhao🇨🇳 · Jin-Lei Yang🇨🇳

    Based on the gauge symmetry group $SU(3{)}_C\otimes SU(2{)}_L\otimes U(1{)}_Y\otimes U(1{)}_{B-L}$, the minimal supersymmetric extension of the SM with local B-L gauge symmetry(B-LSSM) has been introduced. In this model, we study the Higgs masses with the one-loop zero temperature effective potential corrections. Besides, the finite temperature effective potentials connected with two $U(1{)}_{B-L}$ Higgs singlets are deduced specifically. Then we can obtain the gravitational wave spectrums generated from the strong first-order phase transition. In the B-LSSM, the gravitational wave signals can be as strong as $h^2{\Omega }_{GW}\sim 10^{-11}$, which may be detectable in the future experiments.

    hep-phJHEP(2021)·5 citations
20. 20*

    Radiative corrections to the lepton current in unpolarized elastic $lp$-interaction for fixed $Q^2$ and scattering angle

    A. Afanasev🇺🇸 · A. Ilyichev🇧🇾

    The kinematical difference between the description of radiative effects for fixed $Q^2$ vs a fixed scattering angle in the elastic lepton-proton ($lp$)-scattering is discussed. The technique of calculation as well as explicit expressions for radiative corrections to the lepton current in unpolarized elastic $lp$-scattering for these two cases are presented without using an ultrarelativistic approximation. A comparative numerical analysis within kinematic conditions of Jefferson Lab measurements and MUSE experiment in PSI is performed.

    hep-phEPJA(2021)·11 citations
21. 21*

    Sensitivity to Triple Higgs Couplings via Di-Higgs Production in the 2HDM at e+e- Colliders

    F. Arco🇪🇸 · S. Heinemeyer🇪🇸 · M.J. Herrero🇪🇸

    An important task at future colliders is the investigation of the Higgs-boson sector. Here the measurement of the triple Higgs coupling(s) plays a special role. Based on previous analyses, within the framework of Two Higgs Doublet Models (2HDM) type~I and~II, we define and analyze several two-dimensional benchmark planes, that are over large parts in agreement with all theoretical and experimental constraints. For these planes we evaluate di-Higgs production cross sections at future high-energy $e^{+}{e}^{-}$ colliders, such as ILC or CLIC. We consider two different channels for the neutral di-Higgs pairs $h_i{h}_j=hh,hH,HH,AA$: $e^{+}{e}^{-}\to h_i{h}_{j}Z$ and $e^{+}{e}^{-}\to h_i{h}_j\nu \bar{\nu }$. In both channels the various triple Higgs-boson couplings contribute substantially. We find regions with a strong enhancement of the production channel of two SM-like light Higgs bosons and/or with very large production cross sections involving one light and one heavy or two heavy 2HDM Higgs bosons, offering interesting prospects for the ILC or CLIC. The mechanisms leading to these enhanced production cross sections are analyzed in detail. We propose the use of cross section distributions with the invariant mass of the two final Higgs bosons where the contributions from intermediate resonant and non-resonant BSM Higgs bosons play a crucial role. We outline which process at which center-of-mass energy would be best suited to probe the corresponding triple Higgs-boson couplings.

    hep-phEPJC(2021)·19 citations
22. 22*

    Dark Moments for the Standard Model ?

    Thomas G. Rizzo🇺🇸

    If dark matter (DM) interacts with the Standard Model (SM) via the kinetic mixing (KM) portal, it necessitates the existence of portal matter (PM) particles which carry both dark and SM quantum numbers that will appear in vacuum polarization-like loop graphs. In addition to the familiar $\sim eϵQ$ strength, QED-like interaction for the dark photon (DP), in some setups different loop graphs of these PM states can also induce other coupling structures for the SM fermions that may come to dominate in at least some regions of parameter space regions and which can take the form of `dark' moments, eg, magnetic dipole-type interactions in the IR, associated with a large mass scale, $\Lambda$. In this paper, motivated by a simple toy model, we perform a phenomenological investigation of a possible loop-induced dark magnetic dipole moment for SM fermions, in particular, for the electron. We show that at the phenomenological level such a scenario can not only be made compatible with existing experimental constraints for a significant range of correlated values for $\Lambda$ and the dark $U(1{)}_D$ gauge coupling, $g_D$, but can also lead to quantitatively different signatures once the DP is discovered. In this setup, assuming complex scalar DM to satisfy CMB constraints, parameter space regions where the DP decays invisibly are found to be somewhat preferred if PM mass limits from direct searches at the LHC and our toy model setup are all taken seriously. High precision searches for, or measurements of, the $e^{+}{e}^{-}\to \gamma +\mathrm{DP}$ process at Belle II are shown to provide some of the strongest future constraints on this scenario.

    hep-phJHEP(2021)·18 citations
23. 23*

    Average minijet rapidity ratios in Mueller-Navelet jets

    Nauzet Bethencourt de León🇪🇸 · Grigorios Chachamis🇵🇹 · Agustín Sabio Vera🇪🇸

    We investigate different final state features in Mueller-Navelet jets events at hadron colliders. The focus lies on the average rapidity ratio between subsequent minijet emissions which has been investigated in previous works but now is modified to also incorporate the transverse momenta together with the rapidities of the emitted jets. We study the dependence of this observable on a lower transverse momentum veto which does affect the typical minijet multiplicity of the events under scrutiny. We find that this observable is stable when including higher order quantum corrections, also when collinear terms are resummed to all orders.

    hep-phEPJC(2021)·26 citations
24. 24*

    The $q_T$ and $\Delta \varphi$ spectra in W and Z production at the LHC at N${}^3$LL'+N${}^2$LO

    Wan-Li Ju🇬🇧 · Marek Schönherr🇬🇧

    The production of weak gauge bosons, $W^{\pm }$ and $Z$, are at the core of the LHC precision measurement program. Their transverse momentum spectra as well as their pairwise ratios are key theoretical inputs to many high-precision analyses, ranging from the $W$ mass measurement to the determination of parton distribution functions. Owing to the different properties of the $W$ and $Z$ boson and the different accessible fiducial regions for their measurement, a simple one-dimensional correlation is insufficient to capture the differing vector and axial-vector dynamics of the produced lepton pair. We propose to correlate them in two observables, the transverse momentum $q_T$ of the lepton pair and its azimuthal separation $\Delta \varphi$. Both quantities are purely transverse and therefore accessible in all three processes, either directly or by utilising the missing transverse momentum of the event. We calculate all the single-differential $q_T$ and $\Delta \varphi$ as well as the double-differential $(q_T,\Delta \varphi )$ spectra for all three processes at N${}^3$LL'+N${}^2$LO accuracy, resumming small transverse momentum logarithms in the soft-collinear effective theory approach and including all singlet and non-singlet contributions. Using the double-differential cross sections we build the pairwise ratios ${\mathcal{R}}_{W^{+}/Z},{\mathcal{R}}_{W^{-}/Z},{\mathcal{R}}_{W^{+}/W^{-}}$ and determine their uncertainties assuming fully correlated, partially correlated, and uncorrelated uncertainties in the respective numerators and denominators. In the preferred partially correlated case we find uncertainties of less than 1% in most phase space regions and up to 3% in the lowest $q_T$ region.

    hep-phhep-exJHEP(2021)·59 citations
25. 25*

    W+charm production with massive c quarks in PowHel

    G. Bevilacqua🇭🇺 · M.V. Garzelli🇩🇪 · A. Kardos🇭🇺 · L.Toth🇭🇺

    The hadroproduction of a $W$ boson in association with a charm quark at the Large Hadron Collider is at the centre of current investigations due to its potential to probe the strangeness content of the proton. In this paper we present an implementation of the $W+c$ production process in the PowHel event generator matched to the PYTHIA8 parton shower approach, allowing to obtain predictions for differential cross-sections with NLO QCD accuracy matched to the accuracy of the Shower Monte Carlo event generator. Effects of non-diagonal CKM matrix elements, finite charm quark mass and off-shell $W$ decays including spin correlations are taken into account. We investigate the production of a leptonically decaying $W$ boson in association with either a charmed meson ($W^{\pm }+D^{\ast \mp }$) or a charmed jet ($W^{\pm }+j_c$) and compare our predictions with particle-level measurements by the ATLAS and CMS collaborations at $\sqrt{s}=$ 7 and 13 TeV. Considering the level of agreement between theory predictions and experimental data in the light of present theoretical and experimental uncertainties, our results do not point to the need of extensive modifications of the strange and antistrange distribution functions in the NLO PDF fits that we used, although collider $W+c$ production data have not been included yet in these fits.

    hep-phJHEP(2022)·20 citations
26. 26*

    Jet tomography in heavy ion collisions with deep learning

    Yi-Lun Du🇳🇴 · Daniel Pablos🇮🇹 · Konrad Tywoniuk🇳🇴

    Deep learning techniques have the power to identify the degree of modification of high energy jets traversing deconfined QCD matter on a jet-by-jet basis. Such knowledge allows us to study jets based on their initial, rather than final energy. We show how this new technique provides unique access to the genuine configuration profile of jets over the transverse plane of the nuclear collision, both with respect to their production point and their orientation. Effectively removing the selection biases induced by final-state interactions, one can in this way analyse the potential azimuthal anisotropies of jet production associated to initial-state effects. Additionally, we demonstrate the capability of our new method to locate with precision the production point of a dijet pair in the nuclear overlap region, in what constitutes an important step forward towards the long term quest of using jets as tomographic probes of the quark-gluon plasma.

    hep-phPRL(2022)·51 citations
27. 27*

    General Remarks on the One-loop Contributions to the Muon Anomalous Magnetic Moment

    Bingrong Yu🇨🇳 · Shun Zhou🇨🇳

    The latest measurement of the muon anomalous magnetic moment $a_{\mu }^{}\equiv (g_{\mu }^{}-2)/2$ at the Fermi Laboratory has found a $4.2\sigma$ discrepancy with the theoretical prediction of the Standard Model (SM). Motivated by this exciting progress, we investigate in the present paper the general one-loop contributions to $a_{\mu }^{}$ within the SM and beyond. First, different from previous works, the analytical formulae of relevant loop functions after integration are now derived and put into compact forms with the help of the Passarino-Veltman functions. Second, given the interactions of muon with new particles running in the loop, we clarify when the one-loop contribution to $a_{\mu }^{}$ could take the correct positive sign as desired. Third, possible divergences in the zero- and infinite-mass limits are examined, and the absence of any divergences in the calculations leads to some consistency conditions for the construction of ultraviolet complete models. Applications of our general formulae to specific models, such as the SM, seesaw models, $Z^{\prime }$ and leptoquark models, are also discussed.

    hep-phNPB(2022)·14 citations
28. 28*

    The importance of kinematic twists and genuine saturation effects in dijet production at the Electron-Ion Collider

    Renaud Boussarie🇫🇷 · Heikki Mäntysaari🇫🇮 · Farid Salazar🇺🇸 · Björn Schenke🇺🇸

    We compute the differential yield for quark anti-quark dijet production in high-energy electron-proton and electron-nucleus collisions at small $x$ as a function of the relative momentum ${\mathbf{P}}_{\perp }$ and momentum imbalance ${\mathbf{k}}_{\perp }$ of the dijet system for different photon virtualities $Q^2$, and study the elliptic and quadrangular anisotropies in the relative angle between ${\mathbf{P}}_{\perp }$ and ${\mathbf{k}}_{\perp }$. We review and extend the analysis in [1], which compared the results of the Color Glass Condensate (CGC) with those obtained using the transverse momentum dependent (TMD) framework. In particular, we include in our comparison the improved TMD (ITMD) framework, which resums kinematic power corrections of the ratio $k_{\perp }$ over the hard scale $Q_{\perp }$. By comparing ITMD and CGC results we are able to isolate genuine higher saturation contributions in the ratio $Q_s/Q_{\perp }$ which are resummed only in the CGC. These saturation contributions are in addition to those in the WeizsäckerWilliams gluon TMD that appear in powers of $Q_s/k_{\perp }$. We provide numerical estimates of these contributions for inclusive dijet production at the future Electron-Ion Collider, and identify kinematic windows where they can become relevant in the measurement of dijet and dihadron azimuthal correlations. We argue that such measurements will allow the detailed experimental study of both kinematic power corrections and genuine gluon saturation effects.

    hep-phnucl-thJHEP(2021)·74 citations
29. 29*

    Spectral function of fermions in a highly occupied non-Abelian plasma

    Kirill Boguslavski🇦🇹 · Tuomas Lappi🇫🇮 · Mark Mace🇫🇮 · Sören Schlichting🇩🇪

    We develop a method to obtain fermion spectral functions non-perturbatively in a non-Abelian gauge theory with high occupation numbers of gauge fields. After recovering the free field case, we extract the spectral function of fermions in a highly occupied non-Abelian plasma close to its non-thermal fixed point, i.e., in a self-similar regime of the non-equilibrium dynamics. We find good agreement with hard loop perturbation theory for medium-induced masses, dispersion relations and quasiparticle residues. We also extract the full momentum dependence of the damping rate of the collective excitations.

    hep-phhep-latnucl-thPLB(2022)·19 citations
30. 30*

    Runaway Relaxion from Finite Density

    Reuven Balkin🇮🇱 · Javi Serra🇩🇪 · Konstantin Springmann🇩🇪 · Stefan Stelzl🇩🇪 · Andreas Weiler🇩🇪

    Finite density effects can destabilize the metastable vacua in relaxion models. Focusing on stars as nucleation seeds, we derive the conditions that lead to the formation and runaway of a relaxion bubble of a lower energy minimum than in vacuum. The resulting late-time phase transition in the universe allows us to set new constraints on the parameter space of relaxion models. We also find that similar instabilities can be triggered by the large electromagnetic fields around rotating neutron stars.

    hep-phastro-ph.COastro-ph.HEJHEP(2022)·28 citations
31. 31*

    Threshold resummation of transverse momentum distributions beyond next-to-leading log

    Stefano Forte🇮🇹 · Giovanni Ridolfi🇮🇹 · Simone Rota🇮🇹

    We derive a general expression for the threshold resummation of transverse momentum distributions for processes with a colorless final state, by suitably generalizing the renormalization-group based approach to threshold resummation previously pursued by two of us. The ensuing expression holds to all logarithmic orders, and it can be used to extend available results in the literature, which only hold up to the next-to-leading log (NLL) level. We check agreement of our result with the existing NLL result, as well as against the known fixed next-to-leading order results for the Higgs transverse momentum distribution in gluon fusion, and we provide explicit expressions at the next-to-next-to-leading log level.

    hep-phJHEP(2021)·17 citations
32. 32*

    A model-agnostic analysis of hybrid stars with reactive interfaces

    Germán Lugones🇧🇷 · Mauro Mariani🇦🇷 · Ignacio F. Ranea-Sandoval🇦🇷

    We study hybrid stars considering the effects on stellar stability of the hadron-quark conversion speed at the sharp interface. The equation of state is constructed by combining a model-agnostic hadronic description with a constant speed of sound model for quark matter. We show that current LIGO/Virgo, NICER, low-density nuclear and high-density perturbative QCD constraints can be satisfied in two scenarios, with low and high transition pressures. If the conversion speed at the interface is slow, a new class of dynamically stable hybrid objects is possible and very stiff hadronic equations of state cannot be discarded. Densities tens of times larger than the nuclear saturation density are possible at the center of these objects. We discuss possible formation mechanisms for the new class of hybrid stars and smoking guns for their observational identification.

    ↳ nucl-thastro-ph.HEastro-ph.SRhep-phJCAP(2023)·38 citations
33. 33*

    Constraining Dark Matter Microphysics with the Annihilation Signal from Subhalos

    Jack Runburg🇺🇸 · Eric J. Baxter🇺🇸 · Jason Kumar🇺🇸

    In the cold dark matter scenario, galactic dark matter halos are populated with a large number of smaller subhalos. Previous work has shown that dark matter annihilations in subhalos can generate a distinctive, non-Poisson signal in the gamma-ray photon counts probability distribution function (PDF). Here we show that the gamma-ray PDF also carries information about the velocity dependence of the dark matter annihilation cross section. After calculating the PDF assuming $s$-wave and Sommerfeld-enhanced annihilation, we perform a mock data analysis to illustrate how current and future observations can constrain the microphysics of the dark matter annihilation. We find that, with current Fermi data, and assuming a dark matter annihilation cross section roughly at the limit of current bounds from annihilation in dwarf spheroidal galaxies, one can potentially distinguish the non-Poissonian fluctuations expected from dark matter annihilation in subhalos from Poisson sources, as well as from dark matter models with an incorrect velocity-dependence. We explore how robust these results are to assumptions about the modeling of astrophysical backgrounds. We also point out a four-parameter degeneracy between the velocity dependence of the dark matter annihilation, the minimum subhalo mass, the power law index of the subhalo mass function, and the normalization of the dark matter signal. This degeneracy can be broken with priors from N-body simulations or from observational constraints on the subhalo mass function.

    ↳ astro-ph.COhep-phJCAP(2022)·8 citations
34. 34*

    On attractor and fixed points in Bjorken flows

    Jean-Paul Blaizot🇫🇷 · Li Yan🇨🇳

    We consider a plasma of massless particles undergoing Bjorken expansion, mimicking the matter created in ultra-relativistic heavy ion collisions. We study the transition to hydrodynamics using kinetic theory in the relaxation time approximation. By allowing the relaxation time to depend on time, we can monitor the speed of the transition from the collisionless regime to hydrodynamics. By using a special set of moments of the momentum distribution, we reduce the kinetic equation to a coupled mode problem which encompasses all versions of second order viscous hydrodynamics for Bjorken flows. This coupled mode problem is analysed first using techniques of linear algebra. Then we transform this two mode problem into a single non linear differential equation and proceed to a fixed point analysis. We identify an attractor solution as the particular solution of this non linear equation that joins two fixed points: one corresponding to the collisionless, early time regime, the other corresponding to late time hydrodynamics. We exploit the analytic solution of this equation in order to test several approximations and to identify generic features of the transition to hydrodynamics. We argue that extending the accuracy of hydrodynamics to early time, i.e. to the region of large gradients, amounts essentially to improve the accuracy of the location of the collisionless fixed point. This is demonstrated by showing that a simple renormalisation of a second order transport coefficient puts the free streaming fixed point at the right location, and allows us to reproduce accurately the full solution of the kinetic equation within second order viscous hydrodynamics, even in regimes far from local equilibrium.

    ↳ nucl-thhep-phPRC(2021)·53 citations
35. 35*

    A Causal Framework for Non-Linear Quantum Mechanics

    David E. Kaplan🇺🇸 · Surjeet Rajendran🇺🇸

    We add non-linear and state-dependent terms to quantum field theory. We show that the resulting low-energy theory, non-linear quantum mechanics, is causal, preserves probability and permits a consistent description of the process of measurement. We explore the consequences of such terms and show that non-linear quantum effects can be observed in macroscopic systems even in the presence of de-coherence. We find that current experimental bounds on these non-linearities are weak and propose several experimental methods to significantly probe these effects. The locally exploitable effects of these non-linearities have enormous technological implications. For example, they would allow large scale parallelization of computing (in fact, any other effort) and enable quantum sensing beyond the standard quantum limit. We also expose a fundamental vulnerability of any non-linear modification of quantum mechanics - these modifications are highly sensitive to cosmic history and their locally exploitable effects can dynamically disappear if the observed universe has a tiny overlap with the overall quantum state of the universe, as is predicted in conventional inflationary cosmology. We identify observables that persist in this case and discuss opportunities to detect them in cosmic ray experiments, tests of strong field general relativity and current probes of the equation of state of the universe. Non-linear quantum mechanics also enables novel gravitational phenomena and may open new directions to solve the black hole information problem and uncover the theory underlying quantum field theory and gravitation.

    ↳ hep-thgr-qchep-phquant-phPRD(2022)·46 citations
36. 36*

    Gauge Symmetry Enhancement by Wilson Lines in Twisted Compactification

    H. Itoyama🇯🇵 · Yuichi Koga🇯🇵 · Sota Nakajima🇯🇵

    We point out a simple realization of gauge symmetry enhancement by Wilson lines in QFT with twisted compactification in extra dimensions. We illustrate this in the field contents taken from heterotic supergravity in arbitrary dimensions toroidally compactified.

    ↳ hep-thhep-ph4 citations
37. 37*

    Standardizing reverberation-measured Mg II time-lag quasars, by using the radius-luminosity relation, and constraining cosmological model parameters

    Narayan Khadka🇺🇸 · Zhefu Yu🇺🇸 · Michal Zajaček🇨🇿 · Mary Loli Martinez-Aldama🇵🇱 · Bożena Czerny🇵🇱 · Bharat Ratra🇺🇸

    We use 78 reverberation-measured Mg II time-lag quasars (QSOs) in the redshift range $0.0033\le z\le 1.89$ to constrain cosmological parameters in six different cosmological models. The basis of our method is the use of the radius-luminosity or $R-L$ relation to standardize these 78 Mg II QSOs. In each cosmological model we simultaneously determine $R-L$ relation and cosmological model parameters, thus avoiding the circularity problem. We find that the $R-L$ relation parameter values are independent of the cosmological model used in the analysis thus establishing that current Mg II QSOs are standardizable candles. Cosmological constraints obtained using these QSOs are significantly weaker than, but consistent with, those obtained from a joint analysis of baryon acoustic oscillation (BAO) observations and Hubble parameter [$H(z)$] measurements. So, we also analyse these QSOs in conjunction with the BAO + $H(z)$ data and find cosmological constraints consistent with the standard spatially-flat $\Lambda$CDM model as well as with mild dark energy dynamics and a little spatial curvature. A larger sample of higher-quality reverberation-measured QSOs should have a smaller intrinsic dispersion and so should provide tighter constraints on cosmological parameters.

    ↳ astro-ph.COgr-qchep-phhep-thMNRAS(2021)·44 citations
38. 38*

    Antistars or antimatter cores in mirror neutron stars?

    Zurab Berezhiani🇮🇹

    The oscillation of the neutron $n$ into mirror neutron $n^{\prime }$, its partner from dark mirror sector, can gradually transform an ordinary neutron star into a mixed star consisting in part of mirror dark matter. The implications of the reverse process taking place in the mirror neutron stars depend on the sign of baryon asymmetry in mirror sector. Namely, if it is negative, as predicted by certain baryogenesis scenarios, then ${\bar{n}}^{\prime }-\bar{n}$ transitions create a core of our antimatter gravitationally trapped in the mirror star interior. The annihilation of accreted gas on such antimatter cores could explain the origin $\gamma$-source candidates, with unusual spectrum compatible to baryon-antibaryon annihilation, recently identified in the Fermi LAT catalog, In addition, some part of this antimatter escaping after the mergers of mirror neutron stars can produce the flux of cosmic antihelium and also heavier antinuclei which are hunted in the AMS-02 experiment.

    ↳ astro-ph.HEastro-ph.COhep-phnucl-thUniverse(2022)·17 citations
39. 39*

    Multi-messenger heavy-ion collision physics

    Charles Gale🇨🇦 · Jean-François Paquet🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸

    This work studies the production of direct photons in relativistic nuclear collisions, along with the production of hadrons. Radiation from the very first instants to the final moments of the evolution is included. The hybrid model used here describes all stages of relativistic heavy-ion collisions. Chronologically, those are an initial state reflecting the collision of nuclei described within the Color Glass Condensate effective theory; a pre-equilibrium phase based on non-equilibrium linear response; relativistic viscous hydrodynamics, and a hadronic afterburner. The effect of the pre-equilibrium phase on both photonic and hadronic observables is highlighted for the first time. The potential of photon observables -- spectrum, differential elliptic and triangular flow -- to reveal the chemical equilibration time is studied. Finally, we consider "small collision systems", including proton+nucleus collisions and collisions of light nuclei, as probed by hadronic and electromagnetic observables. We demonstrate how photon production can signal the formation of quark-gluon plasma in such small systems.

    ↳ nucl-thhep-phnucl-exPRC(2022)·122 citations
40. 40*

    Studying VLOCV twin compact stars with binary mergers

    Z. Sharifi🇮🇷 · M. Bigdeli🇮🇷 · D. Alvarez-Castillo🇵🇱

    GW170817 has provided valuable constraints on the equations of state of merging binary neutron stars, which can be considered as the most probable candidate for the source of gravitational waves. On the other hand, these natural laboratories of extreme temperature and density may lead to the estimation of some exotic matter like {deconfined quark matter in their cores}. In this paper, we investigate the neutron star matter equation of state (EoS) with the lowest order constrained variational (LOCV) method considering the excluded volume effect (VLOCV) for nucleons {to} compute the tidal deformability of binary neutron star mergers (BNSMs). Within this approach, the size of nucleons makes the EoS {so} stiff that requires a phase transition in order to avoid causality violation. Therefore, this phase transition {may lead} to the appearance of the third family of compact stars {including} ``twin star'' configurations. {Our EoS models are confronted with observations from GW170817, GW190814, GW190425, and also NICER. We find out that regarding all these constraints, the EoS models having the {transition} pressure$\approx$30-100 MeV/fm${}^3$ and the energy density discontinuity $\Delta \epsilon$$\lesssim$300 MeV/fm${}^3$ are preferable.

    ↳ astro-ph.HEhep-phnucl-thPRD(2021)·17 citations
41. 41*

    Probing elastic interactions in the dark sector and the role of $S_8$

    Jose Beltrán Jiménez🇪🇸 · Dario Bettoni🇪🇸 · David Figueruelo🇪🇸 · Florencia Anabella Teppa Pannia🇪🇸 · Shinji Tsujikawa🇯🇵

    We place observational constraints on two models within a class of scenarios featuring an elastic interaction between dark energy and dark matter that only produces momentum exchange up to first order in cosmological perturbations. The first one corresponds to a perfect-fluid model of the dark components with an explicit interacting Lagrangian, where dark energy acts as a dark radiation at early times and behaves as a cosmological constant at late times. The second one is a dynamical dark energy model with a dark radiation component, where the momentum exchange covariantly modifies the conservation equations in the dark sector. Using Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations (BAO), and Supernovae type Ia (SnIa) data, we show that the Hubble tension can be alleviated due to the additional radiation, while the ${\sigma }_8$ tension present in the $\Lambda$-Cold-Dark-Matter model can be eased by the weaker galaxy clustering that occurs in these interacting models. Furthermore, we show that, while CMB+BAO+SnIa data put only upper bounds on the coupling strength, adding low-redshift data in the form of a constraint on the parameter $S_8$ strongly favours nonvanishing values of the interaction parameters. Our findings are in line with other results in the literature that could signal a universal trend of the momentum exchange among the dark sector.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2021)·65 citations
42. 42*

    Unraveling the Flux-Averaged Neutrino-Nucleus Cross Section

    Omar Benhar🇮🇹

    The interpretation of the nuclear cross sections measured using accelerator neutrino beams involve severe difficulties, arising primarily from the average over the incoming neutrino flux. The broad energy distribution of the beam particles hampers the determination of the energy transfer to the nuclear target, the knowledge of which is needed to pin down the dominant reaction mechanism. Overcoming this problem requires the development of a theoretical approach suitable to describe neutrino interactions at energies ranging from hundreds of MeV to few GeV. In this paper, it is argued that the approach based on the factorisation of the nuclear cross section provides a consistent framework for the calculation of neutrino-nucleus interactions in both the quasi elastic and inelastic channels. The near-degeneracy between theoretical models based on different assumptions, and the use of electron scattering data to advance the understanding of neutrino-nucleus cross sections are also discussed.

    ↳ nucl-thhep-phEur.Phys.J.ST(2021)·0 citations
43. 43*

    Searches for beyond-Riemann gravity

    Alan Kostelecky🇺🇸 · Zonghao Li🇺🇸

    Many effective field theories describing gravity cannot arise from an underlying theory based on Riemann geometry or its extensions to include torsion and nonmetricity but may instead emerge from another geometry or may have a nongeometric basis. The Lagrange density for a broad class of such theories is investigated. The action for fermions coupled to gravity is linearized about a Minkowski background and is found to include terms describing small deviations from Lorentz invariance and gravitational gauge invariance. The corresponding nonrelativistic hamiltonian is derived at second order in the fermion momentum. The implications for laboratory experiments and astrophysical observations with fermions are studied, with primary focus on anomalous spin-gravity couplings. First constraints on some coefficients are extracted from existing data obtained via measurements at different potentials, comparisons of gravitational accelerations, interferometric methods, and investigations of gravitational bound states. Some prospects for future experimental studies are discussed.

    ↳ gr-qchep-phPRD(2021)·47 citations
44. 44*

    Symmetry breaking at high temperatures in large N gauge theories

    Soumyadeep Chaudhuri🇮🇱 · Eliezer Rabinovici🇮🇱

    Considering marginally relevant and relevant deformations of the weakly coupled $(3+1)$-dimensional large $N$ conformal gauge theories introduced in arXiv:2011.13981, we study the patterns of phase transitions in these systems that lead to a symmetry-broken phase in the high temperature limit. These deformations involve only the scalar fields in the models. The marginally relevant deformations are obtained by varying certain double trace quartic couplings between the scalar fields. The relevant deformations, on the other hand, are obtained by adding masses to the scalar fields while keeping all the couplings frozen at their fixed point values. At the $N\to \infty$ limit, the RG flows triggered by these deformations approach the aforementioned weakly coupled CFTs in the UV regime. These UV fixed points lie on a conformal manifold with the shape of a circle in the space of couplings. In certain parameter regimes a subset of points on this manifold exhibits thermal order characterized by the spontaneous breaking of a global ${\mathbb{Z}}_2$ or $U(1)$ symmetry and Higgsing of a subset of gauge bosons at all nonzero temperatures. We show that the RG flows triggered by the marginally relevant deformations lead to a weakly coupled IR fixed point which lacks the thermal order. Thus, the systems defined by these RG flows undergo a transition from a disordered phase at low temperatures to an ordered phase at high temperatures. This provides examples of both inverse symmetry breaking and symmetry nonrestoration. For the relevant deformations, we demonstrate that a variety of phase transitions are possible depending on the signs and magnitudes of the masses (squared) added to the scalar fields. Using thermal perturbation theory, we derive the approximate values of the critical temperatures for all these phase transitions. All the results are obtained at the $N\to \infty$ limit.

    ↳ hep-thcond-mat.str-elhep-phJHEP(2021)·24 citations
45. 45*

    Beyond the relaxation time approximation

    Grzegorz Wilk🇵🇱 · Zbigniew Włodarczyk🇵🇱

    The relaxation time approximation (RTA) is a well known method of describing the time evolution of a statistical ensemble by linking distributions of the variables of interest at different stages of their temporal evolution. We show that if all the distributions occurring in the RTA have the same functional form of a quasi-power Tsallis distribution the time evolution of which depends on the time evolution of its control parameter, nonextensivity $q(t)$, then it is more convenient to consider only the time evolution of this control parameter.

    ↳ cond-mat.stat-mechhep-phnucl-thEPJA(2021)·4 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.