Fri·Feb 14, 2020Friday·February 14, 2020

1. 01*

   Probing Early-Time Dynamics and Quark-Gluon Plasma Transport Properties with Photons and Hadrons

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

   We use a hybrid model which relies on QCD effective kinetic theory -- K\oMP\oST -- to dynamically bridge the gap between IP-Glasma initial states and viscous hydrodynamics, for the theoretical interpretation of heavy-ion collision results. The hydrodynamic phase is then followed by dynamical freeze-out handled by UrQMD. It is observed that the new pre-equilibrium/pre-hydro phase does influence the extraction of transport coefficients. We also show how the early dynamics is reflected in photon observables.

   hep-phnucl-exnucl-thNPA(2021)·32 citations
2. 02*

   Sterile neutrino oscillometry with Jinping

   M.V. Smirnov🇨🇳 · Zh.J. Hu🇨🇳 · J.J. Ling🇨🇳 · Yu.N. Novikov🇷🇺 · Z. Wang🇨🇳 · G. Yang🇺🇸

   The existence of sterile neutrino is an open question in neutrino physics up to now. The method of neutrino oscillometry provides a powerful tool to test the common 3+1 sterile neutrino hypothesis, i.e. three active flavors and one sterile falvor. There are several antineutrino sources can be used for this method. One of them is the well known isotope chain of ${}^{144}\mathrm{Ce}-$${}^{144}\mathrm{Pr}$ with initial activity around 50-100 kCi. It has compact size and might be installed either outside or inside the detector. Another one is the short-lived isotope ${}^8\mathrm{Li}$, which can be produced in nuclear reaction of a proton beam hitting beryllium target. The Lithium source has only the out-of-detector option due to its large size. The proposed Jinping water-based liquid scintillator detector will be used as a detection volume. Above experimental setups will allow us to cover the current best fit values of oscillation parameters with 90% C.L. At the same time, it is sensitive to the region of Neutrino-4 result.

   hep-phhep-exEPJC(2020)·6 citations
3. 03*

   Probing the top-Higgs boson FCNC couplings via the $h\to \gamma \gamma$ channel at the HE-LHC and FCC-hh

   Yao-Bei Liu🇨🇳 · Stefano Moretti🇬🇧

   We investigate the sensitivity of future searches for the top-Higgs boson Flavour Changing Neutral Current (FCNC) couplings $tqh$~($q=u,c$) at the proposed High Energy Large Hadron Collider~(HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh). We perform a full simulation for two processes in the $h\to \gamma \gamma$ decay channel (where $h$ is the discovered Higgs state): single top quark FCNC production in association with the Higgs boson (plus a jet) and top quark pair production with FCNC decays $t\to qh$. All the relevant backgrounds are considered in a cut based analysis to obtain the limits on the Branching Ratios (BRs) of $t\to uh$ and $t\to ch$. It is shown that, at the HE-LHC with an integrated luminosity of 15 ab${}^{-1}$ and at the FCC-hh with an integrated luminosity of 30 ab${}^{-1}$, {{the BR($t\to uh$) (BR($t\to ch$)) can be probed, respectively, to $7.0(8.5)\times 10^{-5}$ and $2.3(3.0)\times 10^{-5}$ at the 95\% Confidence Level (CL) (assuming a 10\% systematic uncertainty on the background), which is almost two orders of magnitude better than the current 13 TeV LHC experimental results.

   hep-phPRD(2020)·19 citations
4. 04*

   The stochastic model of neutrino oscillation

   Xiao-Yan Wang🇨🇳 · Xiang-Jun Chen🇨🇳

   Neutrino oscillation is phenomenon of random transition from a flavor state of neutrino to another, and should obey quantum statistics theory, and constitutes Markoffian process. The process is depicted by method of CTRW (continuous time random walk), and the time-evolution formula of flavor distribution of neutrino beam has been established. The simulation with Markoffian model for solar and cosmic ray neutrino indicates neutrino oscillation will arrive at equilibrium flavor distribution of three-fold maximum if propagation time is long enough, which is consistent to the data of SK and SNO experiments.

   hep-ph1 citation
5. 05*

   Estimation of ${\rm Y}$(1S) production in ep process near threshold

   Yu Xu🇨🇳 · Yaping Xie🇨🇳 · Rong Wang🇨🇳 · Xurong Chen🇨🇳

   The near-threshold photo-productions of heavy quarkonia are important ways to test the QCD-inspired models and to constrain the gluon distribution of nucleon in the large x region. Investigating the various models, we choose a photon-gluon fusion model and a pomeron exchange model for J/$\Psi$ photo-production near threshold, emphasising on the explanation of the recent experimental measurement by GlueX at JLab. We find that these two models are not only valid in a wide range of the center-of-mass energy of $\gamma$ and proton, but also can be generalized to describe the ${\rm Y}$(1S) photo-production. Using these two models, we predict the electro-production cross-sections of ${\rm Y}$(1S) at EicC to be 48 fb to 85 fb at the center-of-mass energy of 16.75 GeV.

   hep-phEPJC(2020)·14 citations
6. 06*

   New physics at the MUonE experiment at CERN

   A. Masiero🇮🇹 · P. Paradisi🇮🇹 · M. Passera🇮🇹

   A confirmation of the long-standing muon $g$-2 discrepancy requires both experimental and theoretical progress. On the theory side, the hadronic corrections are under close scrutiny, as they induce the leading uncertainty of the Standard Model prediction. Recently, the MUonE experiment has been proposed at CERN to provide a new determination of the leading hadronic contribution to the muon $g$-2 via the measurement of the differential cross section of muon-electron scattering. The precision expected at this experiment raises the question whether possible new-physics (NP) could affect its measurements. We address this issue studying possible NP signals in muon-electron collisions due to heavy or light mediators, depending on whether their mass is higher or lower than $\mathcal{O}(1\mathrm{GeV})$. We analyze the former in a model-independent way via an effective field theory approach, whereas for the latter we focus on scenarios with light scalar and vector bosons. Using existing experimental bounds, we show that possible NP effects in muon-electron collisions are expected to lie below MUonE's sensitivity. This result confirms and reinforces the physics case of the MUonE proposal.

   hep-phhep-exPRD(2020)·61 citations
7. 07*

   Two-loop corrections to the Higgs trilinear coupling in models with extended scalar sectors

   Johannes Braathen🇯🇵 · Shinya Kanemura🇯🇵

   The Higgs trilinear coupling ${\lambda }_{hhh}$ is of great importance to understand the structure of the Higgs sector and allows searching for indirect signs of Beyond-the-Standard-Model (BSM) physics, even if new states are somehow hidden. In particular, in models with extended Higgs sectors, it is known that non-decouplings effects in BSM-scalar contributions at one loop can cause ${\lambda }_{hhh}$ to deviate significantly from its SM prediction, raising the question of what happens at two loops. We review here our calculation of the leading two-loop corrections to ${\lambda }_{hhh}$ in an aligned scenario of a Two-Higgs-Doublet Model. We find their typical size to be 10-20% of the one-loop corrections, meaning that they do not modify significantly the one-loop non-decoupling effects, but are not entirely negligible either.

   hep-ph1 citation
8. 08*

   Breaking the Grossman-Nir Bound in Kaon Decays

   Xiao-Gang He🇹🇼 · Xiao-Dong Ma🇹🇼 · Jusak Tandean🇹🇼 · German Valencia🇦🇺

   The ratio $\mathcal{B}(K_L\to {\pi }^0\nu \bar{\nu })/\mathcal{B}(K^{+}\to {\pi }^{+}\nu \bar{\nu })$ of the branching fractions of kaon decays $K_L\to {\pi }^0\nu \bar{\nu }$ and $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ has a maximum of about 4.3 under the assumption that the underlying interactions change isospin by $\Delta I=1/2$. This is referred to as the Grossman-Nir (GN) bound, which is respected by the standard model (SM) and by many scenarios beyond it. Recent preliminary results of the KOTO and NA62 Collaborations searching for these kaon modes seem to imply a violation of this bound. The KOTO findings also suggest that $\mathcal{B}(K_L\to {\pi }^0\nu \bar{\nu })$ could be much larger, by nearly two orders of magnitude, than that predicted in the SM. In this work we study the possibility of violating the GN bound in an effective field theory approach with only SM fields. We show that the bound holds, in addition to the original GN scenarios, whether or not the kaon decays conserve lepton number. We demonstrate that the inclusion of $\Delta I=3/2$ operators can lead to a violation of the GN bound and illustrate with an example of how the KOTO numbers may be reached with a new physics scale of order tens of GeV.

   hep-phhep-exJHEP(2020)·25 citations
9. 09*

   Anomalous electromagnetic moments of $\tau$ lepton in $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ reaction in Pb+Pb collisions at the LHC

   Mateusz Dyndal🇨🇭 · Mariola Klusek-Gawenda🇵🇱 · Matthias Schott🇩🇪 · Antoni Szczurek🇵🇱

   We discuss the sensitivity of the $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ process in ultraperipheral Pb+Pb collisions on the anomalous magnetic ($a_{\tau }$) and electric ($d_{\tau }$) moments of $\tau$ lepton at LHC energies. We derive the corresponding cross sections by folding the elementary cross section with the heavy-ion photon fluxes and considering semi-leptonic decays of both $\tau$ leptons in the fiducial volume of ATLAS and CMS detectors. We present predictions for total and differential cross sections, and for the ratios to $\gamma \gamma \to e^{+}{e}^{-}({\mu }^{+}{\mu }^{-}$) process. These ratios allow to cancel theoretical and experimental uncertainties when performing precision measurement of $a_{\tau }$ at the LHC. The expected limits on $a_{\tau }$ with existing Pb+Pb dataset are found to be better by a factor of two comparing to current best experimental limits and can be further improved by another factor of two at High Luminosity LHC.

   hep-phPLB(2020)·95 citations
10. 10*

    A Novel Scenario in the Semi-constrained NMSSM

    Kun Wang🇨🇳 · Jingya Zhu🇨🇳

    In this work, we develop a novel efficient scan method, combining the Heuristically Search (HS) and the Generative Adversarial Network (GAN), where the HS can shift marginal samples to perfect samples, and the GAN can generate a huge amount of recommended samples from noise in a short time. With this efficient method, we find a new scenario in the semi-constrained Next-to Minimal Supersymmetric Standard Model (scNMSSM), or NMSSM with non-universal Higgs masses. In this scenario, (i) Both muon g-2 and right relic density can be satisfied, along with the high mass bound of gluino, etc. As far as we know, that had not been realized in the scNMSSM before this work. (ii) With the right relic density, the lightest neutralinos are singlino-dominated, and can be as light as 0-12 GeV. (iii) The future direct detections XENONnT and LUX-ZEPLIN (LZ-7 2T) can give strong constraints to this scenario. (iv) The current indirect constraints to Higgs invisible decay $h_2\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^0$ are weak, but the direct detection of Higgs invisible decay at the future HL-LHC may cover half of the samples, and that of the CEPC may cover most. (v) The branching ratio of Higgs exotic decay $h_2\to h_1{h}_1,a_1{a}_1$ can be over 20 percent, while their contributions to the invisible decay $h_2\to 4{\chi }_1^0$ are very small.

    hep-phJHEP(2020)·18 citations
11. 11*

    $gg\to ZZ$: analytic two-loop results for the low- and high-energy regions

    Joshua Davies🇩🇪 · Go Mishima🇩🇪 · Matthias Steinhauser🇩🇪 · David Wellmann🇩🇪

    We compute next-to-leading order virtual two-loop corrections to the process $gg\to ZZ$ in the low- and high-energy limits, considering the contributions with virtual top quarks. Analytic results for all 20 form factors are presented including expansion terms up to $1/m_t^{12}$ and $m_t^{32}$. We use a Padé approximation procedure to extend the radius of convergence of the high-energy expansion and apply this approach to the fini\ te virtual next-to-leading order corrections.

    hep-phJHEP(2020)·35 citations
12. 12*

    A possible shortcut for neutron-antineutron oscillation through mirror world

    Zurab Berezhiani🇮🇹

    Existing bounds on the neutron-antineutron mass mixing, ${ϵ}_{n\bar{n}}<\mathrm{few}\times 10^{-24}$ eV, impose a severe upper limit on $n-\bar{n}$ transition probability, $P_{n\bar{n}}(t)<(t/0.1\mathrm{s}{)}^2\times 10^{-18}$ or so, where $t$ is the neutron flight time. Here we propose a new mechanism of $n-\bar{n}$ transition which is not induced by direct mass mixing ${ϵ}_{n\bar{n}}$ but is mediated instead by the neutron mixings with the hypothetical states of mirror neutron $n^{\prime }$ and mirror antineutron ${\bar{n}}^{\prime }$. The latter can be as large as ${ϵ}_{n{n}^{\prime }},{ϵ}_{n{\bar{n}}^{\prime }}\sim 10^{-15}$ eV or so, without contradicting present experimental limits and nuclear stability bounds. The probabilities of $n-n^{\prime }$ and $n-{\bar{n}}^{\prime }$ transitions, $P_{n{n}^{\prime }}$ and $P_{n{\bar{n}}^{\prime }}$, depend on environmental conditions in mirror sector, and they can be resonantly amplified by applying the magnetic field of the proper value. This opens up a possibility of $n-\bar{n}$ transition with the probability $P_{n\bar{n}}\simeq P_{n{n}^{\prime }}{P}_{n{\bar{n}}^{\prime }}$ which can reach the values $\sim 10^{-8}$ or even larger. For finding this effect in real experiments, the magnetic field should not be suppressed but properly varied. These mixings can be induced by new physics at the scale of few TeV which may also originate a new low scale co-baryogenesis mechanism between ordinary and mirror sectors.

    hep-phnucl-thEPJC(2021)·37 citations
13. 13*

    On leptonic width of $X(4260)$

    Qin-Fang Cao🇨🇳 · Hong-Rong Qi🇨🇳 · Guang-Yi Tang🇨🇳 · Yun-Feng Xue🇨🇳 · Han-Qing Zheng🇨🇳

    New measurements on cross sections in $e^{+}{e}^{-}\to J/\psi {\pi }^{+}{\pi }^{-}$, $h_c{\pi }^{+}{\pi }^{-}$, $D^0{D}^{\ast -}{\pi }^{+}+c.c.$, $\psi (2S){\pi }^{+}{\pi }^{-}$, $\omega {\chi }_{c0}$ and $J/\psi \eta$ channels have been carried out by BESIII, Belle and BABAR collaborations, and also in the $D_s^{\ast }{\bar{D}}_s^{\ast }$ channel. We perform extensive numerical analyses by combining all these data available, together with those in $D{\bar{D}}^{\ast }$ and $D^{\ast }{\bar{D}}^{\ast }$ channels. Though the latter show no evident peak around $\sqrt{s}=4.230$ GeV, the missing $X(4260)$ is explained as that it is concealed by the interference effects of the well established charmonia $\psi (4040)$, $\psi (4160)$ and $\psi (4415)$. Our analyses reveal that the leptonic decay width of $X(4260)$ ranges from $O(10^2)$ eV to $O(1)$ keV, and hence may be explained in the conventional quark model picture. That is, the $X(4260)$ may well be interpreted as a mixture of $4^3{S}_1$ and $3^3{D}_1$ states.

    hep-phEPJC(2021)·14 citations
14. 14*

    Lepton Flavor Violation and Dilepton Tails at the LHC

    Andrei Angelescu🇺🇸 · Darius A. Faroughy🇨🇭 · Olcyr Sumensari🇮🇹

    Starting from a general effective Lagrangian for lepton flavor violation (LFV) in quark-lepton transitions, we derive constraints on the effective coefficients from the high-mass tails of the dilepton processes $pp\to {\ell }_k{\ell }_l$ (with $k\ne l$). The current (projected) limits derived in this paper from LHC data with $36{\mathrm{fb}}^{-1}$ ($3{\mathrm{ab}}^{-1}$) can be applied to generic new physics scenarios, including the ones with scalar, vector and tensor effective operators. For purely left-handed operators, we explicitly compare these LHC constraints with the ones derived from flavor-physics observables, illustrating the complementarity of these different probes. While flavor physics is typically more constraining for quark-flavor violating operators, we find that LHC provides the most stringent limits on several flavor-conserving ones. Furthermore, we show that dilepton tails offer the best probes for charm-quark transitions at current luminosities and that they provide competitive limits for tauonic $b\to d$ transitions at the high-luminosity LHC phase. As a by-product, we also provide general numerical expressions for several low-energy LFV processes, such as the semi-leptonic decays $K\to \pi {\ell }_k^{\pm }{\ell }_l^{\mp }$, $B\to \pi {\ell }_k^{\pm }{\ell }_l^{\mp }$ and $B\to K^{(\ast )}{\ell }_k^{\pm }{\ell }_l^{\mp }$.

    hep-phhep-exEPJC(2020)·92 citations
15. 15*

    Updates on SM predictions of $|V_{cb}|$ and $R(D^{\ast })$ in $B\to D^{\ast }\ell {\nu }_{\ell }$ decays

    Sneha Jaiswal🇮🇳 · Soumitra Nandi🇮🇳 · Sunando Kumar Patra🇮🇳

    We update the standard model (SM) predictions of $R(D^{\ast })$ using the latest results on the decay distributions in $B\to D^{\ast }\ell {\nu }_{\ell }$ ($\ell =\mu ,e$) by Belle collaboration, while extracting $|V_{cb}|$ at the same time. Depending on the inputs used in the analysis, we define various fit scenarios. Although the central values of the predicted $R(D^{\ast })$ in all the scenarios have reduced from its earlier predictions in 2017, the results are consistent with each other within the uncertainties. In this analysis, our prediction of $R(D^{\ast })$ is consistent with the respective world average at $\sim 3\sigma$. We have also predicted several angular observables associated with $B\to D^{\ast }\tau {\nu }_{\tau }$ decays. We note that the predicted $F_L(D^{\ast })$ is consistent with the corresponding measurement at 2$\sigma$. Utilizing these new results, we fit the Wilson coefficients appearing beyond the standard model of particle physics (BSM). To see the trend of SM predictions, we have utilized the recently published preliminary results on the form-factors at non-zero recoil by the lattice groups like Fermilab-MILC and JLQCD and predicted the observables in $B\to D^{\ast }\ell {\nu }_{\ell }$, and $B\to D^{\ast }\tau {\nu }_{\tau }$ decays.

    hep-phhep-exhep-latJHEP(2020)·48 citations
16. 16*

    Two- and Three-Loop Data for Groomed Jet Mass

    Adam Kardos🇭🇺 · Andrew J. Larkoski🇺🇸 · Zoltán Trócsányi🇭🇺

    We discuss the status of resummation of large logarithmic contributions to groomed event shapes of hadronic final states in electron-positron annihilation. We identify the missing ingredients needed for next-to-next-to-next-to-leading logarithmic (NNNLL) resummation of the mMDT groomed jet mass in $e^{+}{e}^{-}$ collisions: the low-scale collinear-soft constants at two-loop accuracy, $c_{S_c}^{(2)}$, and the three-loop non-cusp anomalous dimension of the global soft function, ${\gamma }_S^{(2)}$. We present a method for extracting those constants using fixed-order codes: the EVENT2 program to obtain the color coefficients of $c_{S_c}^{(2)}$, and MCCSM for extracting ${\gamma }_S^{(2)}$. We present all necessary formulae for resummation of the mMDT groomed heavy jet mass distribution at NNNLL accuracy.

    hep-phhep-exPRD(2020)·22 citations
17. 17*

    Production of axionlike particles in $PbPb$ collisions at the LHC, HE -- LHC and FCC: A phenomenological analysis

    R. O. Coelho🇧🇷 · V. P. Goncalves🇧🇷 · D. E. Martins🇧🇷 · M. S. Rangel🇧🇷

    The production of axionlike particles (ALP) in ultraperipheral $PbPb$ collisions (UPHIC) is investigated considering the energies of the next run of the Large Hadron Collider (LHC) and of the future High Energy -- LHC (HE -- LHC) and Future Circular Collider (FCC). Assuming four different combinations for the ALP mass and coupling and the typical exclusivity cuts for central and forward detectors, we estimate the cross section and invariant mass, rapidity, transverse momentum and {acoplanarity} distributions associated to the diphoton final state produced in the $\gamma \gamma \to a\to \gamma \gamma$ subprocesses. A detailed analysis of the backgrounds is performed. We demonstrate that the backgrounds can be strongly reduced by the exclusivity cuts and that a forward detector, as the LHCb, is ideal to probe an ALP with small mass. Finally, our results indicate that a future experimental analysis of the diphoton final state in UPHIC can probe the existence and properties of axionlike particles.

    hep-phhep-exPLB(2020)·25 citations
18. 18*

    Early thermalization and shear viscosity to entropy ratio in heavy-ion collisions at energies of BES, FAIR and NICA

    E. Zabrodin🇳🇴 · L. Bravina🇳🇴 · M. Teslyk🇳🇴 · O. Vitiuk🇺🇦

    Equilibration of highly excited baryon-rich matter is studied within the microscopic model calculations in A+A collisions at energies of BES, FAIR and NICA. It is shown that the system evolution from the very beginning of the collision can be approximated by relativistic hydrodynamics, although the hot and dense nuclear matter is not in local equilibrium yet. During the evolution of the fireball the extracted values of energy density, net baryon and net strangeness densities are used as an input to Statistical Model (SM) in order to calculate temperature $T$, chemical potentials ${\mu }_B$ and ${\mu }_S$, and entropy density $s$ of the system. Also, they are used as an input for the box with periodic boundary conditions to investigate the momentum correlators in the infinite nuclear matter. Shear viscosity $\eta$ is calculated according to the Green-Kubo formalism. At all energies, shear viscosity to entropy density ratio shows minimum at time corresponding to maximum baryon density. The ratio dependence on $T,{\mu }_B,{\mu }_S$ is investigated for both in- and out of equilibrium cases.

    ↳ nucl-thhep-phnucl-exNPA(2021)·5 citations
19. 19*

    Revisiting Bayesian constraints on the transport coefficients of QCD

    J.-F. Paquet🇺🇸 · A. Angerami🇺🇸 · S. A. Bass🇺🇸 · S. Cao · Y. Chen🇺🇸 · J. Coleman🇺🇸 · L. Cunqueiro🇺🇸 · T. Dai🇺🇸 · L. Du🇺🇸 · R. Ehlers🇺🇸 · H. Elfner🇩🇪 · D. Everett🇺🇸 and 38 other authors

    Multistage models based on relativistic viscous hydrodynamics have proven successful in describing hadron measurements from relativistic nuclear collisions. These measurements are sensitive to the shear and the bulk viscosities of QCD and provide a unique opportunity to constrain these transport coefficients. Bayesian analyses can be used to obtain systematic constraints on the viscosities of QCD, through methodical model-to-data comparisons. In this manuscript, we discuss recent developments in Bayesian analyses of heavy ion collision data. We highlight the essential role of closure tests in validating a Bayesian analysis before comparison with measurements. We discuss the role of the emulator that is used as proxy for the multistage theoretical model. We use an ongoing Bayesian analysis of soft hadron measurements by the JETSCAPE Collaboration as context for the discussion.

    ↳ nucl-thhep-phNPA(2021)·26 citations
20. 20*

    On Boundaries, Charges and Fermi Fields

    J. Mourad🇫🇷 · A. Sagnotti🇮🇹

    We address some general issues related to torsion and Noether currents for Fermi fields in the presence of boundaries, with emphasis on the conditions that guarantee charge conservation. We also describe exact solutions of these boundary conditions and some implications for string vacua with broken supersymmetry.

    ↳ hep-thgr-qchep-phmath-ph+1PLB(2020)·10 citations
21. 21*

    Non-perturbative path integral quantization of the electroweak model: the Maxwell integration

    M. P. Fry🇮🇪

    The non-perturbative path integral quantization of the electroweak model is confronted with an apparent instability when integrating over the Maxwell potential $A_{\mu }$ due to the fast growth of the box graphs $AAAA$ and $AAAZ$ for large amplitude variations of $A_{\mu }$. $Z_{\mu }$ is from the vector part of the weak neutral current. These graphs are unavoidable because they are conditionally convergent and have to be isolated in the model's exact Euclidean one-loop effective action arising from its fermion determinants. A previous QED calculation of the large amplitude variation of its fermion determinant for a class of random potentials showed that the $AAAA$ box graph cancels in this limit. Using this result it is shown that within the electroweak model large amplitude variations of $A_{\mu }$ for fixed $Z_{\mu }$ in a superposition of these fields cancel the $AAAA$ and $AAAZ$ graphs, thereby removing an apparent obstacle to the model's non-perturbative quantization. A negative paramagnetic term in the remainder opposes the effective action's growth for such variations. Its calculation requires knowledge of the degeneracy of the bound states of a charged fermion in the four-dimensional magnetic fields generated by the functional measure of $A_{\mu }$.

    ↳ hep-thhep-phPRD(2020)·1 citation
22. 22*

    Topological thermalization via vortex formation in ultra-fast quenches

    Marcos Tello-Fraile🇪🇸 · Andrés Cano🇫🇷 · Manuel Donaire🇪🇸

    We investigate the thermalization of a two-component scalar field across a second-order phase transition under extremely fast quenches. We find that vortices start developing at the final temperature of the quench, i.e., below the critical point. Specifically, we find that vortices emerge once the fluctuating field departures from its symmetric state and evolves towards a metastable and inhomogenous configuration. The density of primordial vortices at the relaxation time is a decreasing function of the final temperature of the quench. Subsequently, vortices and antivortices annihilate at a rate that eventually determines the total thermalization time. This rate decreases if the theory contains a discrete anisotropy, which otherwise leaves the primordial vortex density unaffected. Our results thus establish a link between the topological processes involved in the vortex dynamics and the delay in the thermalization of the system.

    ↳ cond-mat.stat-mechcond-mat.mtrl-scihep-phPRE(2020)·0 citations
23. 23*

    Transition Probabilities for Flavor Eigenstates of Non-Hermitian Hamiltonians in the PT-Broken Phase

    Tommy Ohlsson🇸🇪 · Shun Zhou🇨🇳

    We investigate the transition probabilities for the "flavor" eigenstates in the two-level quantum system, which is described by a non-Hermitian Hamiltonian with the parity and time-reversal (PT) symmetry. Particularly, we concentrate on the so-called PT-broken phase, where two eigenvalues of the non-Hermitian Hamiltonian turn out to be a complex conjugate pair. In this case, we find that the transition probabilities will be unbounded in the limit of infinite time $t\to +\infty$. However, after performing a connection between a non-Hermitian system, which exhibits passive PT-symmetry and global decay, and the neutral-meson system in particle physics, we observe that the diverging behavior of the transition probabilities is actually applicable to the gauge-transformed neutral-meson states, whereas the transition probabilities for physical states are exponentially suppressed by the global decay. We also present a brief review on the situation at the so-called exceptional point, where both the eigenvalues and eigenvectors of the Hamiltonian coalesce.

    ↳ quant-phhep-phhep-thmath-ph+1J.Math.Phys.(2021)·7 citations
24. 24*

    Gravitational-Wave Implications for the Parity Symmetry of Gravity at GeV Scale

    Yi-Fan Wang🇩🇪 · Rui Niu🇨🇳 · Tao Zhu🇨🇳 · Wen Zhao🇨🇳

    Einstein's general relativity, as the most successful theory of gravity, is one of the cornerstones of modern physics. However, the experimental tests for gravity in the high energy region are limited. The emerging gravitational-wave astronomy has opened an avenue for probing the fundamental properties of gravity in strong and dynamical field, and in particular, high energy regime. In this work, we test the parity conservation of gravity with gravitational waves. If the parity symmetry is broken, the left- and right-handed modes of gravitational waves would follow different equations of motion, dubbed as birefringence. We perform full Bayesian inference by comparing the state-of-the-art waveform with parity violation with the compact binary coalescence data released by LIGO and Virgo collaboration. We do not find any violations of general relativity, thus constrain the lower bound of the parity-violating energy scale to be $0.09$ GeV through the velocity birefringence of gravitational waves. This provides the most stringent experimental test of gravitational parity symmetry up to date. We also find third generation gravitational-wave detectors can enhance this bound to $\mathcal{O}(10^2)$ GeV if there is still no violation, comparable to the current LHC energy scale in particle physics, which indicates gravitational-wave astronomy can usher in a new era of testing the ultraviolet behavior of gravity in the high energy region.

    ↳ gr-qcastro-ph.HEhep-phApJ(2021)·65 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.