Mon·Jun 27, 2022Monday·June 27, 2022

1. 01*

   Photoproduction of $J/\psi$ in d+Au ultraperipheral collisions at the BNL Relativistic Heavy Ion Collider

   V. Guzey (St. Petersburg, INP)🇷🇺 · E. Kryshen (St. Petersburg, INP)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (St. Petersburg, INP)🇷🇺

   We argue that the STAR data on $J/\psi$ photoproduction in $d+Au$ ultraperipheral collisions (UPCs) at the momentum transfer $t\ne 0$ primarily probes elastic and possibly nucleon-dissociative $J/\psi$ photoproduction on quasi-free nucleons, while being essentially insensitive to expectedly weak nuclear modifications of the gluon distribution in the deuteron. Analyzing the STAR detector capabilities for selection of UPC events, we explore the possibility that the contribution of nucleon-dissociative $J/\psi$ photoproduction is negligibly small and obtain a very good description of the $t$ dependence of the STAR total cross section.

   hep-phhep-exnucl-exPRC(2022)·3 citations
2. 02*

   ${\Lambda }_b\to {\Lambda }_c$ Form Factors from QCD Light-Cone Sum Rules

   Yan Miao🇨🇳 · Hui Deng🇨🇳 · Ke-Sheng Huang🇨🇳 · Jing Gao🇨🇳 · Yue-Long Shen🇨🇳

   In this work, we calculate the transition form factors of ${\Lambda }_b$ decaying into ${\Lambda }_c$ within the framework of light-cone sum rules with the distribution amplitudes (DAs) of ${\Lambda }_b$-baryon. In the hadronic representation of the correlation function, we have isolated both the ${\Lambda }_c$ and the ${\Lambda }_c^{\ast }$ states so that the ${\Lambda }_b\to {\Lambda }_c$ form factors can be obtained without ambiguity. We investigate the P-type and A-type current to interpolate the light baryons for a comparison since the interpolation current for the baryon state is not unique. We also employ three parametrization models for DAs of ${\Lambda }_b$ in the numerical calculation. We present the numerical predictions on the ${\Lambda }_b\to {\Lambda }_c$ form factors and the branching fractions, the averaged forward-backward asymmetry , the averaged final hadron polarization and the averaged lepton polarization of the ${\Lambda }_b\to {\Lambda }_c\ell \mu$ decays, as well as the ratio of branching ratios $R_{{\Lambda }_c}$, and the predicted $R_{{\Lambda }_c}$ can be consistent with the LHCb data.

   hep-phCPC(2022)·21 citations
3. 03*

   The Novel Scaling of Tsallis Parameters from the Transverse Momentum Spectra of Charged Particles in Heavy-Ion Collisions

   J.Q. Tao🇨🇳 · W.H. Wu🇨🇳 · M. Wang🇨🇳 · H. Zheng🇨🇳 · W.C. Zhang🇨🇳 · L.L. Zhu🇨🇳 · A. Bonasera🇺🇸

   The transverse momentum $(p_T)$ spectra of charged particles measured in Au + Au collisions from the beam energy scan (BES) program, Cu + Cu collisions at $\sqrt{s_{NN}}=62.4$, 200 GeV at the RHIC and Pb + Pb, Xe + Xe collisions at the LHC are investigated in the framework of Tsallis thermodynamics. The theory can describe the experimental data well for all the collision systems, energies and centralities investigated. The collision energy and centrality dependence of the Tsallis distribution parameters, i.e., the temperature $T$ and the nonextensive parameter $q$, for the \mbox{A + A} collisions are also studied and discussed. A novel scaling between the temperature divided by the natural logarithm of collision energy $(T/\ln \sqrt{s})$ and the nonextensive parameter $q$ is presented.

   hep-phParticles(2022)·14 citations
4. 04*

   Gravitational Form Factors and Mechanical Properties of the Proton : Connection Between Distributions in 2D and 3D

   Poonam Choudhary🇮🇳 · Bheemsehan Gurjar🇮🇳 · Dipankar Chakrabarti🇮🇳 · Asmita Mukherjee🇮🇳

   The gravitational form factors which are obtained from the matrix elements of the energy-momentum tensor provide us information about internal distributions of mass, energy, pressure and shear. The Druck term is the least understood among all the gravitational form factors. In a light front quark-diquark model of proton, we investigate the Druck form factor. Using Abel transformation, we evaluate the 3D distribution in the Breit frame from the 2D light front distributions. The results are compared with other models and lattice predictions.

   hep-phPRD(2022)·33 citations
5. 05*

   Dark photon superradiance quenched by dark matter

   Enrico Cannizzaro🇮🇹 · Laura Sberna🇩🇪 · Andrea Caputo🇮🇱 · Paolo Pani🇮🇹

   Black-hole superradiance has been used to place very strong bounds on a variety of models of ultralight bosons such as axions, new light scalars, and dark photons. It is common lore to believe that superradiance bounds are broadly model independent and therefore pretty robust. In this work we show however that superradiance bounds on dark photons can be challenged by simple, compelling extensions of the minimal model. In particular, if the dark photon populates a larger dark sector and couples to dark fermions playing the role of dark matter, then superradiance bounds can easily be circumvented, depending on the mass and (dark) charge of the dark matter.

   hep-phastro-ph.HEgr-qcPRD(2022)·22 citations
6. 06*

   Thermalization of gluons in spatially homogeneous systems

   Sergio Barrera Cabodevila🇪🇸 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸

   We investigate thermalization of gluons in spatially homogeneous systems using the Boltzmann equation in diffusion approximation. A complete picture on thermalization is obtained for both initially under- and over-populated systems. In an initially under-populated system, we find that its soft sector undergoes three stages: overheating, cooling/overcooling and reheating before full thermalization is achieved. In an initially over-populated system, we find that its soft sector only undergoes two stages towards full thermalization: overheating and cooling. The cooling stage is consistently driven by momentum broadening due to multiple elastic collisions, manifest as a non-thermal scaling solution.

   hep-phnucl-thPLB(2022)·14 citations
7. 07*

   Towards Powerful Probes of Neutrino Self-Interactions in Supernovae

   Po-Wen Chang🇺🇸 · Ivan Esteban🇺🇸 · John F. Beacom🇺🇸 · Todd A. Thompson🇺🇸 · Christopher M. Hirata🇺🇸

   Neutrinos remain mysterious. As an example, enhanced self-interactions ($\nu$SI), which would have broad implications, are allowed. At the high neutrino densities within core-collapse supernovae, $\nu$SI should be important, but robust observables have been lacking. We show that $\nu$SI make neutrinos form a tightly coupled fluid that expands under relativistic hydrodynamics. The outflow becomes either a burst or a steady-state wind; which occurs here is uncertain. Though the diffusive environment where neutrinos are produced may make a wind more likely, further work is needed to determine when each case is realized. In the burst-outflow case, $\nu$SI increase the duration of the neutrino signal, and even a simple analysis of SN 1987A data has powerful sensitivity. For the wind-outflow case, we outline several promising ideas that may lead to new observables. Combined, these results are important steps towards solving the 35-year-old puzzle of how $\nu$SI affect supernovae.

   hep-phastro-ph.COastro-ph.HEhep-ex+1PRL(2023)·66 citations
8. 08*

   Dark photon vortex formation and dynamics

   William E. East🇨🇦 · Junwu Huang🇨🇦

   We study the formation and evolution of vortices in $U(1)$ dark photon dark matter and dark photon clouds that arise through black hole superradiance. We show how the production of both longitudinal mode and transverse mode dark photon dark matter can lead to the formation of vortices. After vortex formation, the energy stored in the dark photon dark matter will be transformed into a large number of vortex strings, eradicating the coherent dark photon dark matter field. In the case where a dark photon magnetic field is produced, bundles of vortex strings are formed in a superheated phase transition, and evolve towards a configuration consisting of many string loops that are uncorrelated on large scales, analogous to a melting phase transition in condensed matter. In the process, they dissipate via dark photon and gravitational wave emission, offering a target for experimental searches. Vortex strings were also recently shown to form in dark photon superradiance clouds around black holes, and we discuss the dynamics and observational consequences of this phenomenon with phenomenologically motivated parameters. In that case, the string loops ejected from the superradiance cloud, apart from producing gravitational waves, are also quantised magnetic flux lines and can be looked for with magnetometers. We discuss the connection between the dynamics in these scenarios and similar vortex dynamics found in type II superconductors.

   hep-phastro-ph.COgr-qcJHEP(2022)·60 citations
9. 09*

   Fermionic dark matter interaction with the photon and the proton in the quantum field-theoretical approach and generalizations

   G. B. de Gracia🇧🇷 · R. da Rocha🇧🇷

   Mass dimension one quantum fields, constructed upon eigenspinors of the charge conjugation operator with dual helicity (ELKO), are prime candidates to describe dark matter. Their interaction with the photon and the proton, in scattering processes, are here explored and discussed, using both the standard QFT with a Maxwell gauge field and a generalized QFT also involving a Podolsky gauge sector. Renormalization and radiative corrections are analyzed in the ELKO setup, in the context of a generalized spinor dual and the twisted conjugation, both yielding unitarity. Several applications are scrutinized, involving the inherent darkness underlying ELKO construction and galaxies rotation curves, the non-relativistic potential regime, and the Møller-like scattering involving ELKO.

   ↳ hep-thhep-ph6 citations
10. 10*

    Quark anomalous magnetic moment leads to the inverse magnetic catalysis phenomena of chiral restoration and deconfinement phase transitions in ${\mu }_B-T$ plane

    Shijun Mao🇨🇳

    The effect of quark anomalous magnetic moment (AMM) to chiral restoration and deconfinement phase transitions in baryon chemical potential-temperature $({\mu }_B-T)$ plane under magnetic fields is investigated in frame of a Pauli-Villars regularized PNJL model. It's found that the quark AMM plays the role of inverse catalysis to the phase transitions, and large quark AMM will change the magnetic catalysis phenomena of phase transitions to inverse magnetic catalysis in the whole ${\mu }_B-T$ plane. For a fixed magnetic field, the critical temperature $T_c$ and critical baryon chemical potential ${\mu }_B^c$ decreases with quark AMM. The stronger the magnetic field is, the inverse catalysis effect of AMM becomes more important. For a small AMM $\kappa ={\kappa }_1$, it shows the magnetic catalysis effect for critical temperature $T_c$ at vanishing ${\mu }_B$ with increasing magnetic field, and (inverse) magnetic catalysis effect for critical baryon chemical potential ${\mu }_B^c$ at vanishing $T$ under (weak) strong magnetic field. At finite $T$ and ${\mu }_B$, there exist some crossings of the phase transition lines with different magnetic field. For a large AMM $\kappa ={\kappa }_2$, we obtain the inverse magnetic catalysis effect in the whole ${\mu }_B-T$ plane, and no crossings of phase transition lines happen.

    ↳ nucl-thhep-phPRD(2022)·21 citations
11. 11*

    The composition of cosmic rays according to the data on EAS cores

    S. B. Shaulov🇷🇺 · V. A. Ryabov🇷🇺 · S. E. Pyatovsky🇷🇺 · A. L. Shepetov🇷🇺 · V. V. Zhukov🇩🇪

    The main purpose of this work is to find the causes of the break of the cosmic ray spectrum at an energy of 3 PeV, which is called the knee. The solution of the problem is associated with the determination of the nuclear composition of cosmic rays in the knee area. The conclusions of this work are based on the analysis of the characteristics of the EAS cores obtained using X-ray emulsion chambers. According to these data, a number of anomalous effects are observed in the knee region, such as scaling violation in the spectra of secondary hadrons, an excess of muons in EAS with gamma families and others. At the same energies equivalent to 1-100 PeV the laboratory system colliders show scaling behavior. So analysis of the data on the EAS cores suggests that the knee in their spectrum is formed by a component of cosmic rays of a non-nuclear nature, possibly consisting of stable (quasi-stable) particles of hypothetical strange quark matter, which named strangelets. This is the only model of the knee compatible with the magnetic rigidity of the nuclear spectra break R=100 TV. In fact, stranglets are stable heavy quasi-nuclei with a positive electric charge of Z=30-1000, so the mechanism of their acceleration coincides with the nuclear one. The break of the cosmic ray spectrum can be associated with a significantly larger mass of strangelets compared to nuclei.

    ↳ astro-ph.HEhep-phSciPost Phys.Proc.(2023)·0 citations
12. 12*

    Stochastic formalism for U(1) gauge fields in axion inflation

    Tomohiro Fujita🇯🇵 · Kyohei Mukaida🇯🇵 · Yuichiro Tada🇯🇵

    We develop the stochastic formalism for $\mathrm{U}(1)$ gauge fields that has the Chern-Simons coupling to a rolling pseudo-scalar field during inflation. The Langevin equations for the physical electromagnetic fields are derived and the analytic solutions are studied. Using numerical simulation we demonstrate that the electromagnetic fields averaged over the Hubble scale continuously change their direction and their amplitudes fluctuate around the analytically obtained expectation values. Though the isotropy is spontaneously broken by picking up a particular local Hubble patch, each Hubble patch is understood independent and the isotropy is conserved globally by averaging all the Hubble patches.

    ↳ astro-ph.COgr-qchep-phJCAP(2022)·8 citations
13. 13*

    Angular analysis of $B^{+}\to {\rho }^{+}{\rho }^0$ decays reconstructed in 2019, 2020, and 2021 Belle II data

    Belle II Collaboration: F. Abudinén · I. Adachi · K. Adamczyk · L. Aggarwal · P. Ahlburg · H. Ahmed · J. K. Ahn · H. Aihara · N. Akopov · A. Aloisio · F. Ameli · L. Andricek and 582 other authors

    We report on a Belle II measurement of the branching fraction ($\mathcal{B}$), longitudinal polarization fraction ($f_L$), and CP asymmetry (${\mathcal{A}}_{CP}$) of $B^{+}\to {\rho }^{+}{\rho }^0$ decays. We reconstruct $B^{+}\to {\rho }^{+}(\to {\pi }^{+}{\pi }^0(\to \gamma \gamma )){\rho }^0(\to {\pi }^{+}{\pi }^{-})$ decays in a sample of SuperKEKB electron-positron collisions collected by the Belle II experiment in 2019, 2020, and 2021 at the ${\rm Y}$(4S) resonance and corresponding to 190 fb${}^{-1}$ of integrated luminosity. We fit the distributions of the difference between expected and observed $B$ candidate energy, continuum-suppression discriminant, dipion masses, and decay angles of the selected samples, to determine a signal yield of $345\pm 31$ events. The signal yields are corrected for efficiencies determined from simulation and control data samples to obtain $\mathcal{B}(B^{+}\to {\rho }^{+}{\rho }^0)=[23.2_{-2.1}^{+2.2}(\mathrm{stat})\pm 2.7(\mathrm{syst})]\times 10^{-6}$, $f_L=0.943_{-0.033}^{+0.035}(\mathrm{stat})\pm 0.027(\mathrm{syst})$, and ${\mathcal{A}}_{CP}=-0.069\pm 0.068(\mathrm{stat})\pm 0.060(\mathrm{syst})$. The results agree with previous measurements. This is the first measurement of ${\mathcal{A}}_{CP}$ in $B^{+}\to {\rho }^{+}{\rho }^0$ decays reported by Belle II.

    ↳ hep-exhep-ph12 citations
14. 14*

    The origin and evolution of the normal Type Ia SN 2018aoz with infant-phase reddening and excess emission

    Yuan Qi Ni · Dae-Sik Moon · Maria R. Drout · Abigail Polin · David J. Sand · Santiago GonzÁlez-GaitÁn · Sang Chul Kim🇰🇷 · Youngdae Lee · Hong Soo Park · D. Andrew Howell · Peter E. Nugent🇺🇸 · Anthony L. Piro and 31 other authors

    SN~2018aoz is a Type Ia SN with a $B$-band plateau and excess emission in the infant-phase light curves $\lesssim$ 1 day after first light, evidencing an over-density of surface iron-peak elements as shown in our previous study. Here, we advance the constraints on the nature and origin of SN~2018aoz based on its evolution until the nebular phase. Near-peak spectroscopic features show the SN is intermediate between two subtypes of normal Type Ia: Core-Normal and Broad-Line. The excess emission could have contributions from the radioactive decay of surface iron-peak elements as well as ejecta interaction with either the binary companion or a small torus of circumstellar material. Nebular-phase limits on H$\alpha$ and He~I favour a white dwarf companion, consistent with the small companion size constrained by the low early SN luminosity, while the absence of [O~I] and He~I disfavours a violent merger of the progenitor. Of the two main explosion mechanisms proposed to explain the distribution of surface iron-peak elements in SN~2018aoz, the asymmetric Chandrasekhar-mass explosion is less consistent with the progenitor constraints and the observed blueshifts of nebular-phase [Fe~II] and [Ni~II]. The helium-shell double-detonation explosion is compatible with the observed lack of C spectral features, but current 1-D models are incompatible with the infant-phase excess emission, $B_{\max }-V_{\max }$ color, and absence of nebular-phase [Ca~II]. Although the explosion processes of SN~2018aoz still need to be more precisely understood, the same processes could produce a significant fraction of Type Ia SNe that appear normal after $\sim$ 1 day.

    ↳ astro-ph.SRastro-ph.HEhep-phApJ(2023)·22 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.