Tue·Mar 30, 2021Tuesday·March 30, 2021

1. 01*

   Decaying fermionic warm dark matter and XENON1T electronic recoil excess

   Koushik Dutta🇮🇳 · Avirup Ghosh🇮🇳 · Arpan Kar🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   In the light of the recently observed XENON1T electronic recoil (ER) data, we investigate the possibility of constraining the parameter space of a generic fermionic warm dark matter (WDM), decaying into a standard model (SM) neutrino and a photon. The photon as a decay product, when produced inside the XENON1T chamber, interacts with an electron of a xenon (Xe) atom, leading to a contribution in the observed ER data. We add this dark matter (DM) induced signal over the standard background (${\mathrm{B}}_0$) considered by the XENON1T collaboration and perform a ${\chi }^2$ fit against the XENON1T data to obtain the best-fit values of the DM decay width and the associated $95\%$ confidence level (C.L.) band for DM mass ($m_{\chi }$) varied in the range $2-60$ keV. Additionally, we have extended our analysis by including two other background models available in the literature and in each case, the corresponding limits on the DM decay width are estimated for DM mass ($m_{\chi }$) in the domain $2-18$ keV. By comparing the constraints, obtained by fitting the XENON1T data, with the upper limits arising from various existing astrophysical and cosmological observations, we find that, for the background model ${\mathrm{B}}_0$, a fair amount of the DM parameter space is allowed at $95\%$ C.L. for DM masses outside the range $3.5\mathrm{keV}\lesssim m_{\chi }\lesssim 8.5\mathrm{keV}$. However, in case of other two background models, reasonable parts of the DM parameter space are favoured at $95\%$ C.L. by all astrophysical data for all DM masses in the range $2-18$ keV.

   hep-phastro-ph.HEPhys.Dark Univ.(2021)·9 citations
2. 02*

   Reply to comment on "The $\sigma$-meson: four-quark vs. two-quark components and decay width in a Bethe-Salpeter approach"

   Nico Santowsky🇩🇪 · Gernot Eichmann🇵🇹 · Christian S. Fischer🇩🇪 · Paul C. Wallbott🇩🇪 · Richard Williams🇩🇪

   In a recent comment [1] Blankleider and Kvinikhidze claim that our work [2] is based on a set of inconsistent Bethe-Salpeter equations for the coupling of four-quark to two-quark states. Here we demonstrate that their argument is insubstantial.

   hep-ph4 citations
3. 03*

   Quenching effects in the cumulative jet spectrum

   Adam Takacs🇳🇴 · Konrad Tywoniuk🇳🇴

   The steeply falling jet spectrum induces bias on the medium modifications of jet observables in heavy-ion collisions. To explore this bias, we develop a novel analytic framework to study the quenched jet spectrum, and its cumulative. We include many energy-loss-related effects, such as soft and hard medium induced emissions, broadening, elastic scattering, jet fragmentation, cone size, coherence effects, etc. We show that, different jet spectrum-based observables are connected, e.g., the nuclear modification, spectrum shift, and the quantile procedure. We present the first predictions for the nuclear modification factor and the quantile procedure with cone size dependence. As an example, we compare dijet and boson+jet events to unfold the spectrum bias effects. We improve quark-, and gluon-jet classification using arguments based on the cumulative. Besides pointing out its flexibility, we apply our framework with other energy loss models such as the hybrid weak-, strong-coupling.

   hep-phhep-exhep-thnucl-ex+1JHEP(2021)·36 citations
4. 04*

   Low-scale Resonant Leptogenesis in $SU(5)$ GUT with ${\mathcal{T}}_{13}$ Family Symmetry

   Chee Sheng Fong🇧🇷 · Moinul Hossain Rahat🇺🇸 · Shaikh Saad🇨🇭

   We investigate low-scale resonant leptogenesis in an $SU(5)\times {\mathcal{T}}_{13}$ model where a single high energy phase in the complex Tribimaximal seesaw mixing produces the yet-to-be-observed low energy Dirac and Majorana $CP$ phases. A fourth right-handed neutrino, required to generate viable light neutrino masses within this scenario, also turns out to be necessary for successful resonant leptogenesis where $CP$ asymmetry is produced by the same high energy phase. We derive a lower bound on the right-handed neutrino mass spectrum in the $\mathrm{GeV}$ range, where part of the parameter space, although in tension with Big Bang Nucleosynthesis constrains, can be probed in planned high intensity experiments like DUNE. We also find the existence of a curious upper bound ($\text{TeV}$-scale) on the right-handed neutrino mass spectrum in majority of the parameter space due to significant washout of the resonant asymmetry by lighter right-handed neutrinos. While in most of the parameter space of our model classical Boltzmann equations are sufficient, when right-handed neutrino masses are below the electroweak sphalerons freeze-out temperature we resort to the more general density matrix formalism to take into account decays and oscillations of the right-handed neutrinos as well as their helicities which are relevant when they are relativistic.

   hep-phhep-exPRD(2021)·13 citations
5. 05*

   Production of light flavor and single-charmed hadrons in $pp$ collisions at $\sqrt{s}=5.02$ TeV in an equal-velocity quark combination model

   Hai-hong Li🇨🇳 · Feng-lan Shao🇨🇳 · Jun Song🇨🇳

   We apply an equal-velocity quark combination model to study the production of light-flavor hadrons and single-charmed hadrons at midrapidity in $pp$ collisions at $\sqrt{s}=5.02$ TeV. We find experimental data for $p_T$ spectra of $\Omega$ and $\varphi$ exhibit a quark number scaling property, which is a clear signal of quark combination mechanism at hadronization. Experimental data for $p_T$ spectra of $p$, $\Lambda$, $\Xi$, $\Omega$, $\varphi$ and $K^{\ast 0}$ are systematically described by the model. The non-monotonic $p_T$ dependence of $\Omega /\varphi$ ratio is naturally explained and we find it is closely related to the shape of the logarithm of strange quark $p_T$ distribution. Using $p_T$ spectra of light-flavor quarks obtained from light-flavor hadrons and a $p_T$ spectrum of charm quarks which is consistent with perturbative QCD calculations, the experimental data for differential cross-sections of $D^{0,+}$, $D_s^{+}$ and ${\Lambda }_c^{+}$ as the function of $p_T$ are systematically described. We predict the differential cross-sections of ${\Xi }_c^{0,+}$ and ${\Omega }_c^0$. The ratio ${\Xi }_c^{0,+}/D^0$ in our model is about 0.16 and ${\Omega }_c^0/D^0$ is about 0.012 due to the cascade suppression of strangeness. In addition, the predicted ${\Xi }_c^{0,+}/D^0$ and ${\Omega }_c^0/D^0$ ratios exhibit the non-monotonic dependence on $p_T$ in the low $p_T$ range.

   hep-phCPC(2021)·21 citations
6. 06*

   Naturally Light Dirac Neutrinos from $SO(10)\times U(1{)}_{\psi }$

   Ernest Ma (UC Riverside)🇺🇸

   A new solution is presented where the right-handed neutrino ${\nu }_R$ in $SO(10)$ pairs up with ${\nu }_L$ to form a naturally light Dirac neutrino. It is based on the framework of $E_6\to SO(10)\times U(1{)}_{\psi }$, then $SO(10)\to SU(5)\times U(1{)}_{\chi }$.

   hep-phPLB(2021)·3 citations
7. 07*

   Quasi-two-body $B_{(s)}\to V\pi \pi$ Decays with Resonance $f_0(980)$ in PQCD Approach

   Lei Yang🇨🇳 · Zhi-Tian Zou🇨🇳 · Ying Li🇨🇳 · Xin Liu🇨🇳 · Cui-Hua Li🇨🇳

   Motivated by the measurements of branching fractions of the quasi-two-body decays $B^0\to K^{\ast 0}(f_0(980)\to ){\pi }^{+}{\pi }^{-}$ and $B^0\to {\rho }^0(f_0(980)\to ){\pi }^{+}{\pi }^{-}$, we study the charmless $B\to V(f_0(980)\to ){\pi }^{+}{\pi }^{-}$ decays in the perturbative QCD approach. Supposing that $f_0(980)$ is a two-quark state and mixture of $n\bar{n}=(u\bar{u}+d\bar{d})/\sqrt{2}$ and $s\bar{s}$ with the mixing angle $\theta$, we calculate the branching fractions of these decays with the new introduced $s$-wave ${\pi }^{+}{\pi }^{-}$-pair wave function. When the mixing angle $\theta$ lies in the range $[135^{\circ },155^{\circ }]$, the calculated branching fractions of the $B^0\to K^{\ast 0}{f}_0(980)\to K^{\ast 0}{\pi }^{+}{\pi }^{-}$ and $B^0\to {\rho }^0{f}_0(980)\to {\rho }^0{\pi }^{+}{\pi }^{-}$ decays are in agreement with the experimental data. The branching fractions of other decays could be measured in the current LHCb and Belle II experiments. Considering the isospin symmetry, we also estimate the branching fractions of the quasi-two-body decays $B\to V{f}_0(980)\to V{\pi }^0{\pi }^0$, which are half of those the corresponding decays $B\to V{f}_0(980)\to V{\pi }^{+}{\pi }^{-}$. Moreover, the direct $CP$ asymmetries of these decays are also calculated, and some of them can be tested in the current experiments.

   hep-phhep-exPRD(2021)·13 citations
8. 08*

   Dark photon production via $\gamma \gamma \to \gamma A^{\prime }$

   Xiaorui Wong🇨🇳 · Yongsheng Huang🇨🇳

   The dark photon is a new gauge boson which arises from an extra U'(1) gauge symmetry. In this paper, a novel dark photon production mechanism based on MeV-scale $\gamma$-$\gamma$ collider is considered: $\gamma \gamma \to \gamma A^{\prime }$. With the aid of PACKAGE-X, differential cross section of $\gamma \gamma \to \gamma A^{\prime }$ is obtained, as a function of the kinetic mixing parameter $\epsilon$ and dark photon mass $m_{A^{\prime }}$. Taking the light-by-light scattering as background, the constraints on the dark photon parameter space for different time intervals in a MeV-scale $\gamma$-$\gamma$ collider are also given.

   hep-phEPJC(2021)·5 citations
9. 09*

   Study of Isothermal Compressibility and Speed of Sound in the Hadronic Matter Formed in Heavy-Ion Collision using Unified Formalism

   Shubahngi Jain🇮🇳 · Rohit Gupta🇮🇳 · Satyajit Jena🇮🇳

   The thermodynamical quantities and response functions are useful to describe the particle production in heavy-ion collisions as they reveal crucial information about the produced system. While the study of isothermal compressibility provides an inference about the viscosity of the medium, speed of sound helps in understanding the equation of state. With an aim towards understanding the system produced in the heavy-ion collision, we have made an attempt to study isothermal compressibility and speed of sound as function of charged particle multiplicity in heavy-ion collisions at $\sqrt{s_{NN}}$ = $2.76$ TeV, $5.02$ TeV, and $5.44$ TeV using unified formalism.

   hep-phUniverse(2023)·12 citations
10. 10*

    Fragmentation function of $g\to Q\bar{Q}{(}^3{S}_1^{[8]})$ in soft gluon factorization and threshold resummation

    An-Ping Chen🇨🇳 · Xiao-Bo Jin🇨🇳 · Yan-Qing Ma🇨🇳 · Ce Meng🇨🇳

    We study the fragmentation function of the gluon to color-octet ${}^3{S}_1$ heavy quark-antiquark pair using the soft gluon factorization (SGF) approach, which expresses the fragmentation function in a form of perturbative short-distance hard part convoluted with one-dimensional color-octet ${}^3{S}_1$ soft gluon distribution (SGD). The short distance hard part is calculated to next-to-leading order in ${\alpha }_s$ and a renormalization group equation for the SGD is derived. By solving the renormalization group equation, threshold logarithms are resummed to all orders in perturbation theory. The comparison with gluon fragmentation function calculated in NRQCD factorization approach indicates that the SGF formula resums a series of velocity corrections in NRQCD which are important for phenomenological study.

    hep-phJHEP(2021)·10 citations
11. 11*

    Topological confinement of vortices in two-flavor dense QCD

    Yuki Fujimoto🇯🇵 · Muneto Nitta🇯🇵

    We find a novel confinement mechanism in the two-flavor dense quark matter proposed recently, that consists of the 2SC condensates and the $P$-wave diquark condensates of $d$-quarks. This quark matter exhibiting color superconductivity as well as superfluidity is classified into two phases; confined and deconfined phases of vortices. We establish that the criterion of the confinement is color neutrality of Aharonov-Bohm (AB) phases: vortices exhibiting color non-singlet AB phases are confined by the so-called AB defects to form color-singlet bound states. In the deconfined phase, the most stable vortices are non-Abelian Alice strings, which are superfluid vortices with fractional circulation and non-Abelian color magnetic fluxes therein, exhibiting color non-singlet AB phases. On the other hand, in the confined phase, these non-Abelian vortices are confined to either a baryonic or mesonic bound state in which constituent vortices are connected by AB defects. The baryonic bound state consists of three non-Abelian Alice strings with different color magnetic fluxes with the total flux canceled out connected by a domain wall junction, while the mesonic bound state consists of two non-Abelian Alice strings with the same color magnetic fluxes connected by a single domain wall. Interestingly, the latter contains a color magnetic flux in its core, but this can exist because of color neutrality of its AB phase.

    hep-phcond-mat.supr-conhep-thJHEP(2021)·14 citations
12. 12*

    Fast neutrino flavor instability and neutrino flavor lepton number crossings

    Taiki Morinaga🇯🇵

    In this paper, we show the equivalency between the existence of fast neutrino flavor instability and that of neutrino flavor lepton number (NFLN) crossings, which indicates that an NFLN angular distribution takes both signs. The veracity of this proposition has been uncertain and sometimes controversial despite its indispensability in the flavor evolutions of dense neutrinos. This study clarifies that the occurrence of an NFLN crossing is both necessary and sufficient for fast instability.

    hep-phastro-ph.HEPRD(2022)·130 citations
13. 13*

    Building up the spectrum of pentaquark states as hadronic molecules

    Bing-Song Zou🇨🇳

    I give a brief comment on the LHCb's discovery of $P_c$ and $P_{cs}$ pentaquark states. These pentaquark states not only reveal a new kind of hadronic molecules, but also shed new light on the possible structure of pentaquark components in baryons, hence may play very important role for understanding un-quenching dynamics and the whole baryon spectroscopy.

    hep-phSci.Bull.(2021)·43 citations
14. 14*

    Neutrino signals of lightcone fluctuations resulting from fluctuating space-time

    Thomas Stuttard🇩🇰

    One of the most common expectations of a quantum theory of gravity is that space-time is uncertain or fluctuating at microscopic scales, making it a stochastic medium for particle propagation. Particles traversing this space-time may experience fluctuations in travel times or velocities, together referred to as lightcone fluctuations, with even very small effects potentially accumulating into observable signals over large distances. In this work we present a heuristic model of lightcone fluctuations and study the resulting modifications to neutrino propagation, including neutrino decoherence and arrival time spread. We show the expected scale of such effects due to `natural' Planck scale physics and consider how they may be observed in neutrino detectors, and compare the potential of neutrinos to $\gamma$-ray astronomy. Using simulations of neutrino mass states propagating in a fluctuating environment, we determine an analytic decoherence operator in the framework of open quantum systems to quantitatively evaluate neutrino decoherence resulting from lightcone fluctuations, allowing experimental constraints on neutrino decoherence to be connected to Planck scale fluctuations in space-time and $\gamma$-ray results.

    hep-phgr-qchep-exPRD(2021)·19 citations
15. 15*

    Phenomenology of the Zee model for Dirac neutrinos and general neutrino interactions

    Julián Calle🇨🇴 · Diego Restrepo🇨🇴 · Óscar Zapata🇨🇴

    The Zee model for Dirac neutrinos is one of the simplest models featuring one-loop Dirac neutrino masses. The interactions between the new scalars (two singly-charged fields) and neutrinos induce general neutrino interactions (GNI) which, as a generalisation of the non standard neutrino interactions, constitute an additional tool to probe models beyond the SM like this. In this work, we consider a $U(1{)}_{B-L}$ gauge symmetry as the responsible for the Diracness of the neutrinos and the radiative character of the neutrino masses. We determine the viable parameter space consistent with neutrino oscillation data, leptonic rare decays and collider constraints, and establish the most relevant experimental prospects regarding lepton flavor violation searches and GNI in future solar neutrino experiments.

    hep-phPRD(2021)·6 citations
16. 16*

    Electrical conductivity of strongly magnetized dense quark matter -- possibility of quantum hall effect

    Jayanta Dey🇮🇳 · Aritra Bandyopadhyay🇨🇳 · Akash Gupta🇩🇪 · Naman Pujari🇮🇳 · Sabyasachi Ghosh🇮🇳

    We have pointed out the possibility of quantum Hall effect or quantum patterns of transportation in a degenerate strongly magnetized quark matter, which might be expected inside a highly dense compact star. An anisotropic pattern of electrical conductivity and resistivity tensor in classical and quantum cases is explored by considering cyclotron motion and Landau quantization respectively. With increasing magnetic field, classical to quantum transitions are realized through enhanced/reduced resistivity/conductivity with jumping pattern. Considering QCD relaxation time scale of 10 fm, $eB\approx (1-4)m_{\pi }^2$ might be considered as strong magnetic field for massless and degenerate quark matter with quark chemical potential $\mu \approx 0.2-0.4$ GeV. Beyond these threshold ranges of magnetic field, perpendicular motion of quarks might be stopped and 3 $\to$ 1 dimensionally reduced conduction picture might be established.

    hep-phastro-ph.SRnucl-thNPA(2023)·20 citations
17. 17*

    A Minimal Supersymmetric SU(5) Missing-Partner Model

    John Ellis🇬🇧 · Jason L. Evans🇨🇳 · Natsumi Nagata🇯🇵 · Keith A. Olive🇺🇸

    We explore a missing-partner model based on the minimal SU(5) gauge group with $75$, $50$ and $\overline{50}$ Higgs representations, assuming a super-GUT CMSSM scenario in which soft supersymmetry-breaking parameters are universal at some high scale $M_{\mathrm{in}}$ above the GUT scale $M_{\mathrm{GUT}}$. We identify regions of parameter space that are consistent with the cosmological dark matter density, the measured Higgs mass and the experimental lower limit on $\tau (p\to K^{+}\nu )$. These constraints can be satisfied simultaneously along stop coannihilation strips in the super-GUT CMSSM with $\tan \beta \sim 3.5-5$ where the input gaugino mass $m_{1/2}\sim 15-25$~TeV, corresponding after strong renormalization by the large GUT Higgs representations between $M_{\mathrm{in}}$ and $M_{\mathrm{GUT}}$ to $m_{\mathrm{LSP}},m_{{\tilde{t}}_1}\sim 2.5-5$~TeV and $m_{\tilde{g}}\sim 13-20$~TeV, with the light-flavor squarks significantly heavier. We find that $\tau (p\to K^{+}\nu )\lesssim 3\times 10^{34}$~yrs throughout the allowed range of parameter space, within the range of the next generation of searches with the JUNO, DUNE and Hyper-Kamiokande experiments.

    hep-phEPJC(2021)·3 citations
18. 18*

    Renormalization of the topological charge density in QCD with dimensional regularization

    Martin Lüscher🇨🇭 · Peter Weisz🇩🇪

    To all orders of perturbation theory, the renormalization of the topological charge density in dimensionally regularized QCD is shown to require no more than an additive renormalization proportional to the divergence of the flavour-singlet axial current. The proof is based on the standard BRS analysis of the QCD vertex functional in the background gauge and exploits the special algebraic properties of the charge density through the Stora--Zumino chain of descent equations.

    hep-phhep-latEPJC(2021)·14 citations
19. 19*

    Interaction of supernova neutrinos with stochastic gravitational waves

    Maxim Dvornikov (IZMIRAN)🇷🇺

    We examine the propagation and flavor oscillations of neutrinos under the influence of gravitational waves (GWs) with an arbitrary polarization. We rederive the effective Hamiltonian for the system of three neutrino flavors using the perturbative approach. Then, using this result, we consider the evolution of neutrino flavors in stochastic GWs with a general energy density spectrum. The equation for the density matrix is obtained and solved analytically in the case of three neutrino flavors. As an application, we study the evolution of the flavor content of a neutrino beam emitted in a core-collapsing supernova. We obtain the analytical expressions for the contributions of GWs to the neutrino fluxes and for the damping decrement, which describes the attenuation of the fluxes to their asymptotic values. We find that the contribution to the evolution of neutrino fluxes from GWs, emitted by merging supermassive black holes, dominates over that from black holes with stellar masses. The implication of the obtained results for the measurement of astrophysical neutrinos with neutrino telescopes is discussed.

    hep-phastro-ph.HEgr-qcPRD(2021)·23 citations
20. 20*

    Impact of the Bounds on the Direct Search for Neutralino Dark Matter on Naturalness

    Manuel Drees🇩🇪 · Ghazaal Ghaffari🇩🇪

    In the Minimal Supersymmetric Extension of the Standard Model (MSSM) the higgsino mass parameter $\mu$ appears both in the masses of the Higgs bosons and in the neutralino mass matrix. Electroweak finetuning therefore prefers small values of $|\mu |$. On the other hand, bino--like neutralinos make a good dark matter candidate. We show that current direct search limits then impose a strong lower bound on $|\mu |$, in particular for $\mu >0$ or if the masses of the heavy Higgs bosons of the MSSM are near their current limit from LHC searches. There is therefore some tension between finetuning and neutralino dark matter in the MSSM. We also provide simple analytical expressions which in most cases closely reproduce the numerical results.

    hep-phPRD(2021)·4 citations
21. 21*

    A view of flavour physics in 2021

    Riccardo Barbieri🇮🇹

    Based on a view of current flavour physics and motivated by the hierarchy problem and by the pattern of quark masses and mixings, I describe a picture of flavour physics that should give rise in a not too distant future to observable deviations from the SM in Higgs compositeness and/or in B-decays with violations of Lepton Flavour Universality, as hinted by current data, or perhaps even in supersymmetry, depending on the specific realisation.

    hep-phActa Phys.Polon.B(2021)·30 citations
22. 22*

    Nonequilibrium Dynamics of the Chiral Quark Condensate under a Strong Magnetic Field

    Gastao Krein🇧🇷 · Carlisson Miller🇧🇷

    Strong magnetic fields impact quantum-chromodynamics (QCD) properties in several situations; examples include the early universe, magnetars, and heavy-ion collisions. These examples share a common trait: time evolution. A prominent QCD property impacted by a strong magnetic field is the quark condensate, an approximate order parameter of the QCD transition between a high-temperature quark-gluon phase and a low-temperature hadronic phase. We use the linear sigma model with quarks to address the quark condensate time evolution under a strong magnetic field. We use the closed time path formalism of nonequilibrium quantum field theory to integrate out the quarks and obtain a mean-field Langevin equation for the condensate. The Langevin equation features dissipation and noise kernels controlled by a damping coefficient. We compute the damping coefficient for magnetic field and temperature values achieved in peripheral relativistic heavy-ion collisions and solve the Langevin equation for a temperature quench scenario. The magnetic field changes the dissipation and noise pattern by increasing the damping coefficient compared to the zero-field case. An increased damping coefficient increases fluctuations and time scales controlling condensate's short-time evolution, a feature that can impact hadron formation at the QCD transition. The formalism developed here can be extended to include other order parameters, hydrodynamic modes, and system's expansion to address magnetic field effects in complex settings as heavy-ion collisions, the early universe, and magnetars.

    hep-phhep-thnucl-thSymmetry(2021)·12 citations
23. 23*

    Proton Mass Decomposition and Hadron Cosmological Constant

    Keh-Fei Liu🇺🇸

    Lattice results on sigma terms and global analysis of parton momentum fractions are used to give the quark and glue fractions of the proton mass and rest energy. The mass decomposition in terms of the trace of the energy-momentum tensor is renormalization group invariant. The decomposition of the rest energy from the Hamiltonian and the gravitational form factors are scheme and scale dependent. The separation of the energy-momentum tensor into the traceless part which is composed of the quark and glue parton momentum fractions and the trace part has the minimum scheme dependence. We identify the glue part of the trace anomaly $⟨H_{\beta }⟩$ as the vacuum energy from the glue condensate in the vacuum. From the metric term of the gravitational form factors, which is the stress part of the stress-energy-momentum tensor, we find that the trace part of the rest energy, dominated by $⟨H_{\beta }⟩$, gives a {\it constant} restoring pressure which balances that from the traceless part of the Hamiltonian to confine the hadron, much like the cosmological constant Einstein introduced for a static universe. From a lattice calculation of $⟨H_{\beta }⟩$ in the charmonium, we deduce the associated string tension which turns out to be in good agreement with that from a Cornell potential which fits the charmonium spectrum.

    hep-phhep-lathep-thnucl-thPRD(2021)·38 citations
24. 24*

    A multi-temperature universe can allow a sub-MeV dark photon dark matter

    Amin Aboubrahim🇩🇪 · Wan-Zhe Feng🇨🇳 · Pran Nath🇺🇸 · Zhu-Yao Wang🇺🇸

    An analysis of sub-MeV dark photon as dark matter is given which is achieved with two hidden sectors, one of which interacts directly with the visible sector while the second has only indirect coupling with the visible sector. The formalism for the evolution of three bath temperatures for the visible sector and the two hidden sectors is developed and utilized in solution of Boltzmann equations coupling the three sectors. We present exclusion plots where the sub-MeV dark photon can be dark matter. The analysis can be extended to a multi-temperature universe with multiple hidden sectors and multiple heat baths.

    hep-phJHEP(2021)·20 citations
25. 25*

    Direct detection of dark energy: the XENON1T excess and future prospects

    Sunny Vagnozzi🇬🇧 · Luca Visinelli🇳🇱 · Philippe Brax🇫🇷 · Anne-Christine Davis🇬🇧 · Jeremy Sakstein🇺🇸

    We explore the prospects for direct detection of dark energy by current and upcoming terrestrial dark matter direct detection experiments. If dark energy is driven by a new light degree of freedom coupled to matter and photons then dark energy quanta are predicted to be produced in the Sun. These quanta free-stream towards Earth where they can interact with Standard Model particles in the detection chambers of direct detection experiments, presenting the possibility that these experiments could be used to test dark energy. Screening mechanisms, which suppress fifth forces associated with new light particles, and are a necessary feature of many dark energy models, prevent production processes from occurring in the core of the Sun, and similarly, in the cores of red giant, horizontal branch, and white dwarf stars. Instead, the coupling of dark energy to photons leads to production in the strong magnetic field of the solar tachocline via a mechanism analogous to the Primakoff process. This then allows for detectable signals on Earth while evading the strong constraints that would typically result from stellar probes of new light particles. As an example, we examine whether the electron recoil excess recently reported by the XENON1T collaboration can be explained by chameleon-screened dark energy, and find that such a model is preferred over the background-only hypothesis at the $2.0\sigma$ level, in a large range of parameter space not excluded by stellar (or other) probes. This raises the tantalizing possibility that XENON1T may have achieved the first direct detection of dark energy. Finally, we study the prospects for confirming this scenario using planned future detectors such as XENONnT, PandaX-4T, and LUX-ZEPLIN.

    hep-phastro-ph.COgr-qchep-exPRD(2021)·101 citations
26. 26*

    Constructing on-shell operator basis for all masses and spins

    Zi-Yu Dong🇨🇳 · Teng Ma🇮🇱 · Jing Shu🇨🇳

    We first propose a general method to construct the complete set of on-shell operator bases involving massive particles with any spins. To incorporate the non-abelian little groups of massive particles, the on-shell scattering amplitude basis should be factorized into two parts: one is charged, and the other one is neutral under little groups of massive particles. The complete set of these two parts can be systematically constructed by choosing some specific Young diagrams of Lorentz subgroup and global symmetry $U(N)$ respectively ($N$ is the number of external particles), without the equation of motion and integration by part redundancy. Thus the complete massive amplitude bases without any redundancies can be obtained by combining these two complete sets. Some examples are presented to explicitly demonstrate this method. This method is applicable for constructing amplitude bases involving identical particles, and all the bases can be constructed automatically by computer programs based on it.

    hep-phhep-thPRD(2023)·40 citations
27. 27*

    Differential distributions for Single Top Quark Production at the LHeC

    Meisen Gao🇨🇳 · Jun Gao🇨🇳

    We present a phenomenological study of the single top (anti-)quark production with leptonic decays at the Large Hadron electron Collider (LHeC) at the next-to-leading-order (NLO) in QCD. We focus on various differential distributions in a fiducial region. The NLO corrections can reduce the fiducial cross section by 14%. We find the NLO predictions exhibit strong stability under scale variations for most observables considered while the scale variations at the leading-order (LO) dominated in the theoretical uncertainties. We propose a method of determining the top-quark mass using the measurement of the average transverse momentum of the charged lepton. The scale variations at the NLO induce a theoretical uncertainty of about 1.3 GeV of the extracted top-quark mass. The statistical error of the extracted top-quark mass amounts to 1.1 GeV. We also investigate the impact of the QCD corrections and the scale variations in searches of the anomalous Wtb couplings.

    hep-phPRD(2021)·7 citations
28. 28*

    Constraint on Spinor-Vector Dualities in Six Dimensions

    A.E. Faraggi🇬🇧 · S. Groot Nibbelink · M. Hurtado-Heredia🇬🇧

    Imprints of spinor-vector dualities have been uncovered in various string constructions. They are typically induced by changing certain free general GSO phases in the underlying string partition functions. This paper shows that spinor-vector dualities in six dimensions are constrained by a fundamental effective field theory consistency condition, namely that any six dimensional low energy theory must be free of irreducible SO(2N) anomalies. Aspects of spinor-vector dualities are analysed in four six-dimensional free fermionic models which are distinguished by two generalised GSO phases. In addition, the constraint on the number of spinors and vectors is confirmed on generic spectra which may occur in K3 line bundle compactifications of the heterotic E8xE8 string.

    ↳ hep-thhep-phPRD(2021)·10 citations
29. 29*

    Generalization capabilities of translationally equivariant neural networks

    Srinath Bulusu🇦🇹 · Matteo Favoni🇦🇹 · Andreas Ipp🇦🇹 · David I. Müller🇦🇹 · Daniel Schuh🇦🇹

    The rising adoption of machine learning in high energy physics and lattice field theory necessitates the re-evaluation of common methods that are widely used in computer vision, which, when applied to problems in physics, can lead to significant drawbacks in terms of performance and generalizability. One particular example for this is the use of neural network architectures that do not reflect the underlying symmetries of the given physical problem. In this work, we focus on complex scalar field theory on a two-dimensional lattice and investigate the benefits of using group equivariant convolutional neural network architectures based on the translation group. For a meaningful comparison, we conduct a systematic search for equivariant and non-equivariant neural network architectures and apply them to various regression and classification tasks. We demonstrate that in most of these tasks our best equivariant architectures can perform and generalize significantly better than their non-equivariant counterparts, which applies not only to physical parameters beyond those represented in the training set, but also to different lattice sizes.

    ↳ hep-latcs.LGhep-phstat.MLPRD(2021)·22 citations
30. 30*

    Constraining viscous dark energy models with the latest cosmological data

    Deng Wang🇨🇳 · Yang-Jie Yan🇨🇳 · Xin-He Meng🇨🇳

    Based on the assumption that the dark energy possessing bulk viscosity is homogenously and isotropically permeated in the universe, we propose three new viscous dark energy (VDE) models to characterize the accelerating universe. By constraining these three models with the latest cosmological observations, we find that they just deviate very slightly from the standard cosmological model and can alleviate effectively the current $H_0$ tension between the local observation by the Hubble Space Telescope and the global measurement by the Planck Satellite. Interestingly, we conclude that a spatially flat universe in our VDE model with cosmic curvature is still supported by current data, and the scale invariant primordial power spectrum is strongly excluded at least at the $5.5\sigma$ confidence level in three VDE models as the Planck result. We also give the $95\%$ upper limits of the typical bulk viscosity parameter $\eta$ in three VDE scenarios.

    ↳ astro-ph.COgr-qchep-phEPJC(2017)·28 citations
31. 31*

    First comprehensive constraints on the Finslerian models using cosmological observations

    Deng Wang🇨🇳 · Xin-He Meng🇨🇳

    We perform the first comprehensive constraints on two Finslerian models, i.e., the simplest Finslerian $\Lambda$CDM (F$\Lambda$) and non-flat F$\Lambda$ models using the Type Ia supernovae, baryonic acoustic oscillations, cosmic microwave background and lensing observations. Using the most stringent constraints we can provide, we find that the constrained typical parameters of both Finslerian models are all consistent with zero at the $2\sigma$ confidence level (C.L.). This means that both Finslerian models just deviate very slightly from the $\Lambda$CDM one, which is also verified by using two geometrical diagnostics to distinguish three different models from each other. We also find that a spatially flat universe is still preferred in the framework of Finsler geometry, that our measured values of the spectral index $n_s$ of primordial power spectrum in both Fisnlerian models exclude the scale invariance at more than $8\sigma$ C.L., and that the current $H_0$ tension can be relieved from $3.4\sigma$ to $2.9\sigma$ and $2.8\sigma$ in the F$\Lambda$ and non-flat F$\Lambda$ models, respectively.

    ↳ astro-ph.COgr-qchep-phPhys.Dark Univ.(2018)·8 citations
32. 32*

    Impacts of new small-scale N-body simulations on dark matter annihilations constrained from cosmological 21cm line observations

    Nagisa Hiroshima🇯🇵 · Kazunori Kohri🇯🇵 · Toyokazu Sekiguchi🇯🇵 · Ryuichi Takahashi🇯🇵

    We revisit constraints on annihilating dark matter based on the global 21cm signature observed by EDGES. For this purpose, we used the numerical data of the latest N-body simulation performed by state-of-the-art standard in order to estimate the boost factor at high redshifts ($z$ = 10 - 100), which enhances the annihilation of dark matter in course of structure formation. By taking into account to what fraction injected energy from dark matter annihilation contributes to ionization, excitation and heating of intergalactic medium during dark ages, we estimated how large the global 21cm absorption can be. By assuming the thermal freezeout scenario, we find that $m_{\mathrm{DM}}<15$ GeV and $m_{\mathrm{DM}}<3$ GeV have been excluded at 95$\%$ C.L. for the annihilation modes into $b\bar{b}$ and $e^{+}{e}^{-}$, respectively.

    ↳ astro-ph.COastro-ph.GAhep-phPRD(2021)·17 citations
33. 33*

    Constitutive relations of a chiral hadronic fluid

    Juan L. Mañes🇪🇸 · Eugenio Megias🇪🇸 · Manuel Valle🇪🇸 · Miguel A. Vazquez-Mozo🇪🇸

    We study the role of non-abelian anomalies in relativistic fluids. To this end, we compute the local functional that solves the anomaly equations, and obtain analytical expressions for the covariant currents and the Bardeen-Zumino terms. We particularize these results to a background with two flavors, and consider the cases of unbroken and broken chiral symmetry. Finally, we provide explicit results for the constitutive relations of chiral nuclear matter interacting with external electromagnetic fields and in presence of chiral imbalance. We emphasize the non-dissipative nature of the chiral electric effect.

    ↳ hep-thcond-mat.str-elhep-phInt.J.Mod.Phys.A(2022)·2 citations
34. 34*

    Jet characterization in Heavy Ion Collisions by QCD-Aware Graph Neural Networks

    Yogesh Verma🇮🇳 · Satyajit Jena🇮🇳

    The identification of jets and their constituents is one of the key problems and challenging task in heavy ion experiments such as experiments at RHIC and LHC. The presence of huge background of soft particles pose a curse for jet finding techniques. The inabilities or lack of efficient techniques to filter out the background lead to a fake or combinatorial jet formation which may have an errorneous interpretation. In this article, we present Graph Reduction technique (GraphRed), a novel class of physics-aware and topology-based attention graph neural network built upon jet physics in heavy ion collisions. This approach directly works with the physical observables of variable-length set of final state particles on an event-by-event basis to find most likely jet-induced particles in an event. This technique demonstrate the robustness and applicability of this method for finding jet-induced particles and show that graph architectures are more efficient than previous frameworks. This technique exhibit foremost time a classifier working on particle-level in each heavy ion event produced at the LHC. We present the applicability and integration of the model with current jet finding algorithms such as FastJet.

    ↳ physics.data-anhep-ph8 citations
35. 35*

    Entanglement Spheres and a UV-IR connection in Effective Field Theories

    Natalie Klco🇺🇸 · Martin J. Savage🇺🇸

    We show that long-distance quantum correlations probe short-distance physics. Two disjoint regions of the latticized, massless scalar field vacuum are numerically demonstrated to become separable at distances beyond the negativity sphere, which extends to infinity in the continuum limit. The size of this quantum coherent volume is determined by the highest momentum mode supported in the identical regions, each of diameter $d$. More generally, effective field theories (EFTs), describing a system up to a given momentum scale $\Lambda$, are expected to share this feature -- entanglement between regions of the vacuum depends upon the UV-completion beyond a separation proportional to $\Lambda$. Through calculations extended to three-dimensions, the magnitude of the negativity at which entanglement becomes sensitive to UV physics in an EFT (lattice or otherwise) is conjectured to scale as $\sim e^{-\Lambda d}$, independent of the number of spatial dimensions. It is concluded that two-region vacuum entanglement at increasing separations depends upon the structure of the theory at increasing momentum scales. This phenomenon may be manifest in perturbative QCD processes.

    ↳ hep-thhep-lathep-phnucl-th+1PRL(2021)·40 citations
36. 36*

    Lattice determination of $I=0$ and 2 $\pi \pi$ scattering phase shifts with a physical pion mass

    T. Blum🇺🇸 · P.A. Boyle🇺🇸 · M. Bruno🇨🇭 · N.H. Christ🇺🇸 · D. Hoying🇺🇸 · C. Kelly🇺🇸 · C. Lehner🇩🇪 · R.D. Mawhinney🇺🇸 · A.S. Meyer🇺🇸 · D.J. Murphy🇺🇸 · C.T. Sachrajda🇬🇧 · A. Soni🇺🇸 · T. Wang🇺🇸

    Phase shifts for $s$-wave $\pi \pi$ scattering in both the $I=0$ and $I=2$ channels are determined from a lattice QCD calculation performed on 741 gauge configurations obeying G-parity boundary conditions with a physical pion mass and lattice size of $32^3\times 64$. These results support our recent study of direct CP violation in $K\to \pi \pi$ decay \cite{Abbott:2020hxn}, improving our earlier 2015 calculation \cite{Bai:2015nea}. The phase shifts are determined for both stationary and moving $\pi \pi$ systems, at three ($I=0$) and four ($I=2$) different total momenta. We implement several $\pi \pi$ interpolating operators including a scalar bilinear "$\sigma$" operator and paired single-pion bilinear operators with the constituent pions carrying various relative momenta. Several techniques, including correlated fitting and a bootstrap determination of p-values have been used to refine the results and a comparison with the generalized eigenvalue problem (GEVP) method is given. A detailed systematic error analysis is performed which allows phase shift results to be presented at a fixed energy.

    ↳ hep-lathep-phnucl-thPRD(2021)·33 citations
37. 37*

    Bounding the photon mass with cosmological propagation of fast radio bursts

    Huimei Wang🇯🇵 · Xueli Miao🇨🇳 · Lijing Shao🇨🇳

    Photon is the fundamental quantum of electromagnetic fields, whose mass, $m_{\gamma }$, should be strictly zero in Maxwell's theory. But not all theories adopt this hypothesis. If the rest mass of the photon is not zero, there will be an additional time delay between photons of different frequencies after they travel through a fixed distance. By analyzing the time delay, we can measure or constrain the photon mass. Fast radio bursts (FRBs) -- transient radio bursts characterized by millisecond duration and cosmological propagation -- are excellent astrophysical laboratories to constrain $m_{\gamma }$. In this work we use a catalog of 129 FRBs in a Bayesian framework to constrain $m_{\gamma }$. As a result, we obtain a new bound on the photon mass, $m_{\gamma }\le 3.1\times 10^{-51}\mathrm{kg}\simeq 1.7\times 10^{-15}eV/{\mathrm{c}}^2$ ($m_{\gamma }\le 3.9\times 10^{-51}\mathrm{kg}\simeq 2.2\times 10^{-15}eV/{\mathrm{c}}^2$) at the $68\%$ $(95\%$) confidence level. The result represents the best limit purely from kinematic analysis of light propagation. The bound on the photon mass will be tighter in the near future with increment in the number of FRBs, more accurate measurement of the redshift for FRBs, and refinement in the knowledge about the origin of dispersion measures (DMs).

    ↳ astro-ph.HEhep-phPLB(2021)·26 citations
38. 38*

    QCD at finite chemical potential in and out-of equilibrium

    Olga Soloveva🇩🇪 · Pierre Moreau🇺🇸 · Elena Bratkovskaya🇩🇪

    We review the transport properties of the strongly interacting quark-gluon plasma (QGP) created in heavy-ion collisions at ultrarelativistic energies, i.e. out-of equilibrium, and compare them to the equilibrium properties. The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_c$ from lattice QCD. We study the transport coefficients such as the ratio of shear viscosity and bulk viscosity over entropy density, diffusion coefficients, electric conductivity etc. versus temperature and baryon chemical potential. Based on a microscopic transport description of heavy-ion collisions we, furthermore, discuss which observables are sensitive to the QGP formation and its properties.

    ↳ nucl-thhep-phPhys.Scripta(2021)·4 citations
39. 39*

    Quantum Gravity in Species Regime

    Gia Dvali🇩🇪

    A large number of particle species allows to formulate quantum gravity in a special double-scaling limit, the species limit. In this regime, quantum gravitational amplitudes simplify substantially. An infinite set of perturbative corrections, that usually blur the picture, vanishes, whereas the collective and non-perturbative effects can be cleanly extracted. Such are the effects that control physics of black holes and of de Sitter and their entanglement curves. In string theory example, we show that the entropy of open strings matches the Gibbons-Hawking entropy of a would-be de Sitter state at the point of saturation of the species bound. This shows, from yet another angle, why quantum gravity/string theory cannot tolerate a de Sitter vacuum. Finally, we discuss various observational implications.

    ↳ hep-thgr-qchep-ph19 citations
40. 40*

    Deuteron-Deuteron Correlation Function in Nucleus-Nucleus Collisions

    Stanislaw Mrowczynski🇵🇱 · Patrycja Slon🇵🇱

    A formula of the $D$-$D$ correlation function is derived. The deuterons are treated either as elementary particles or as neutron-proton bound states. In the first case the deuterons are directly emitted from a source and in the second one the deuteron formation is a final-state process simultaneous with a generation of $D$-$D$ correlation. The source radius of deuterons formed due to final-state interactions is bigger by the factor of $\sqrt{2}$ than that of directly emitted deuterons. To check how sizable is the effect we compute the $D$-$D$ correlation function taking into the Bose-Einstein statistics of deuterons, the $s$-wave scattering due to strong interaction and the Coulomb repulsion. The correlation function is shown to be sensitive to the source radius for sources which are sufficiently small with RMS radii smaller than 3.5 fm. Otherwise the correlation function is dominated by the Coulomb repulsion and weakly depends on the source radius. Measurements which can make use of our finding are discussed.

    ↳ nucl-thhep-phPRC(2021)·22 citations
41. 41*

    Low energy physics of interacting bosons with a moat spectrum, and the implications for condensed matter and cold nuclear matter

    Robert D. Pisarski🇺🇸 · Alexei M. Tsvelik🇺🇸

    We discuss bosonic models with a moat spectrum, where in momentum space the minimum of the dispersion relation is on a sphere of nonzero radius. For spinless bosons with $O(N)$ symmetry, we emphasize the essential difference between $N=2$ and $N>2$. When $N=2$, there are two phase transitions: at zero temperature, a transition to a state with Bose condensation, and at nonzero temperature, a transition to a spatially inhomogeneous state. When $N>2$, previous analysis suggests that a mass gap is generated dynamically at any temperature. In condensed matter, a moat spectrum is important for spin-orbit-coupled bosons. For cold nuclear or quarkyonic matter, we suggest that the transport properties, such as neutrino emission, are dominated by the phonons related to a moat spectrum; also, that at least in the quarkyonic phase the nucleons may be a non-Fermi liquid.

    ↳ nucl-thcond-mat.str-elhep-ph11 citations
42. 42*

    Dispersion Formulas in QFTs, CFTs, and Holography

    David Meltzer🇺🇸

    We study momentum space dispersion formulas in general QFTs and their applications for CFT correlation functions. We show, using two independent methods, that QFT dispersion formulas can be written in terms of causal commutators. The first derivation uses analyticity properties of retarded correlators in momentum space. The second derivation uses the largest time equation and the defining properties of the time-ordered product. At four points we show that the momentum space QFT dispersion formula depends on the same causal double-commutators as the CFT dispersion formula. At $n$-points, the QFT dispersion formula depends on a sum of nested advanced commutators. For CFT four-point functions, we show that the momentum space dispersion formula is equivalent to the CFT dispersion formula, up to possible semi-local terms. We also show that the Polyakov-Regge expansions associated to the momentum space and CFT dispersion formulas are related by a Fourier transform. In the process, we prove that the momentum space conformal blocks of the causal double-commutator are equal to cut Witten diagrams. Finally, by combining the momentum space dispersion formulas with the AdS Cutkosky rules, we find a complete, bulk unitarity method for AdS/CFT correlators in momentum space.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2021)·45 citations
43. 43*

    Analog of gravitational anomaly in topological chiral superconductors

    G.E. Volovik🇫🇮

    It is known that the contribution of torsion to the equation for the chiral Weyl fermions can be equivalently considered in terms of the axial $U(1)$ gauge field. In this scenario the gravitational field transforms to the $U(1)$ gauge field. Here we show that in chiral superconductors the opposite scenario takes place: the electromagnetic $U(1)$ field serves as the spin connection for the Bogoliubov fermionic quasiparticles. As a result the electromagnetic field gives rise to the gravitational anomaly, which contains the extra factor $1/3$ in the corresponding Adler-Bell-Jackiw equation as compared with the conventional chiral anomaly. We also consider the gravitational anomaly produced in neutral Weyl superfluids by the analog of the gravitational instanton, the process of creation and annihilation of the 3D topological objects -- hopfions. The gravitational instanton leads to creation of the chiral charge.

    ↳ cond-mat.supr-congr-qchep-phJETP Lett.(2021)·8 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.