Nuclear Theory·nucl-th

Tuesday·July 25, 2023

18 papers—6 primary·12 cross-listed

07
Electron-positron plasma in BBN: damped-dynamic screening
Christopher Grayson (UArizona)🇺🇸 · Cheng Tao Yang (UArizona)🇺🇸 · Martin Formanek (ELI-Beamlines)🇨🇿 · Johann Rafelski (UArizona)🇺🇸
We characterize in detail the very dense $e^{-} e^{+} γ$ plasma present during the Big-Bang Nucleosynthesis (BBN) and explore how it is perturbed electromagnetically by \lq\lq impurities, {\it i.e.\/}, spatially dispersed protons and light nuclei undergoing thermal motion. The internuclear electromagnetic screened potential is obtained (analytically) using the linear response approach, allowing for the dynamic motion of the electromagnetic field sources and the damping effects due to plasma component scattering. We discuss the limits of the linear response method and suggest additional work needed to improve BBN reaction rates in the primordial Universe. Our theoretical methods to describe the potential between charged dust particles align with previous studies on planetary and space dusty plasma and could have significant impact on interpretation of standard cosmological model results.
↳ astro-ph.COhep-phnucl-thphysics.plasm-phAnnals Phys.(2023)·13 citations
08
Quarkonium transport in strongly coupled plasmas
Govert Nijs🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Xiaojun Yao🇺🇸
Suppression of open heavy flavors and quarkonia in heavy-ion collisions is among the most informative probes of the quark-gluon plasma. Interpreting the full wealth of data obtained from the collision events requires a precise understanding of the evolution of heavy quarks and quarkonia as they propagate through the nearly thermal and strongly coupled plasma. Systematic theoretical studies of quarkonium time evolution in the QGP in the regime where the temperature of the QGP is much smaller than the inverse of quarkonium size have only been carried out in the past few years. Such calculations require the evaluation of a gauge-invariant correlator of chromoelectric fields dressed with Wilson lines, which is similar to, but different from, the correlation used to define the well-known arXiv:hep-ph/0605199 heavy quark diffusion coefficient. The origin of this difference has been explained in arXiv:2107.03945, arXiv:2205.04477, arXiv:2306.13127. Here we show the results of the calculation of the analogous correlator in strongly coupled $N = 4$ SYM using the AdS/CFT correspondence at a finite temperature arXiv:2304.03298. While it resembles the open heavy quark case, it has some crucial differences that highlight the relevance of quantum color correlations. We will also discuss the results for the quarkonium transport coefficients obtained from this correlator, thereby establishing the first analytic results at strong coupling in this context. We find that they vanish in the strong coupling limit for an $N = 4$ SYM plasma with a large number of colors.
↳ hep-phnucl-thPoS(2024)·1 citation
09
Neutron stars in the Witten-Sakai-Sugimoto model
Lorenzo Bartolini🇨🇳 · Sven Bjarke Gudnason🇨🇳
We utilize the top-down holographic QCD model, the Witten-Sakai-Sugimoto model, in a hybrid setting with the SLy4, soft chiral EFT and stiff chiral EFT equations of state to describe neutron stars with high precision. In particular, we employ a calibration that bootstraps the nuclear matter by fitting the Kaluza-Klein scale and the 't Hooft coupling such that the physical saturation density and physical symmetry energy are achieved. We obtain static stable neutron star mass-radius data via the Tolman-Oppenheimer-Volkov equations that yield sufficiently large maximal masses of neutron stars to be compatible with the recently observed PSR-J0952-0607 data as well as all other known radius and tidal deformation constraints.
↳ hep-phnucl-thJHEP(2023)·18 citations
10
Nonextensive effects on the viscous properties of hot and magnetized QCD matter
Shubhalaxmi Rath🇮🇳 · Sadhana Dash🇮🇳
We have studied the effect of the nonextensive Tsallis mechanism on the viscous properties of hot QCD matter in the presence of a strong magnetic field. The results are compared to the case of absence of magnetic field. The viscous coefficients, such as the shear viscosity ( $η$ ) and the bulk viscosity ( $ζ$ ) are determined in the similar environment by utilizing the nonextensive Tsallis mechanism within the relaxation time approximation of kinetic theory. We have observed that, when the nonextensive parameter $q$ is just above unity, both shear and bulk viscosities get increased as compared to their counterparts at $q = 1$ . This enhancement in viscosities is more evident in the additional presence of a strong magnetic field. Furthermore, some observables pertaining to the flow characteristic, fluid behavior and conformal symmetry of the medium are also explored.
↳ hep-phnucl-thEPJA(2024)·8 citations
11
Spin polarization of heavy quarks in matter: predictions from effective field theories
Sourendu Gupta🇮🇳
The spin polarization of heavy quarks in heavy-ion collisions at the LHC is estimated from effective field theories (EFTs). One EFT is similar to the HQET used at zero temperature. This gives a coupling of the heavy quark spin to colour and electromagnetic fields in heavy-ion collisions. The second EFT describes the interaction of heavy quarks and hydrodynamic modes, and gives the coupling between the heavy quark spin and the local vorticity of the fireball. Using these, we find that the measurement of polarization of the heavy quark from small to moderate p_T at the LHC is predicted with a single free parameter proportional to the vorticity. As a result, the heavy quark polarization is the same whether it is derived from the spin alignment of heavy vector mesons or the polarization of heavy baryons. We also predict that the parameter does not differ much between charm and bottom quarks.
↳ hep-phhep-exnucl-exnucl-th1 citation
12
Collins-Soper kernel from lattice QCD at the physical pion mass
Artur Avkhadiev🇺🇸 · Phiala Shanahan🇺🇸 · Michael Wagman🇺🇸 · Yong Zhao🇺🇸
This work presents a determination of the quark Collins-Soper kernel, which relates transverse-momentum-dependent parton distributions (TMDs) at different rapidity scales, using lattice Quantum Chromodynamics (QCD). This is the first lattice QCD calculation of the kernel at quark masses corresponding to a close-to-physical value of the pion mass, with next-to-next-leading logarithmic matching to TMDs from the corresponding lattice-calculable distributions, and includes a complete analysis of systematic uncertainties arising from operator mixing. The kernel is extracted at transverse momentum scales $240 MeV ≲ q_{T} ≲ 1.6 GeV$ with a precision sufficient to begin to discriminate between different phenomenological models in the non-perturbative region.
↳ hep-lathep-phnucl-thPRD(2023)·61 citations
13
Unveiling the properties of the dimuonium at the energies available at the Large Hadron Collider at CERN
C.A. Bertulani🇩🇪 · D. Bhandari🇺🇸 · F.S. Navarra🇧🇷
We study the production of the dimuonium (also known as true muonium) in two and three photon fusion processes in nucleus--nucleus collisions at the CERN Large Hadron Collider (LHC) energies. A new formalism is introduced for the production process and valuable new information is extracted which will be helpful in proposals of future experiments. We explore the phase space constraints, the reaction mechanisms, and how the dimounium decay observables might be jeopardized by other physical processes. We show that the energies available at the large hadron collider at CERN might lead to the first identification of the dimounium in a terrestrial laboratory.
↳ hep-phnucl-thEPJA(2024)·8 citations
14
Polarization of spin-1/2 particles with effective spacetime dependent masses
Samapan Bhadury🇵🇱 · Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Gowthama K. K.🇮🇳 · Radoslaw Ryblewski🇵🇱
Semiclassical expansion of the Wigner function for spin-1/2 fermions having an effective spacetime-dependent mass is used to analyze spin-polarization effects. The existing framework is reformulated to obtain a differential equation directly connecting the particle spin tensor with the effective mass. It reflects the conservation of the total angular momentum in a system. In general, we find that the gradients of mass act as a source of the spin polarization. Although this effect is absent for simple boost-invariant dynamics, an extension to non-boost-invariant systems displays a non-trivial dependence of the spin density on the mass indicating that the spin polarization effects may be intertwined with the phenomenon of chiral restoration.
↳ hep-phnucl-thPLB(2024)·9 citations
15
Thermal conductivity of evolving quark-gluon plasma in the presence of a time-varying magnetic field
Kamaljeet Singh🇮🇳 · Jayanta Dey🇮🇳 · Raghunath Sahoo🇮🇳
The effect of the temperature evolution of QGP on its thermal conductivity and elliptic flow is investigated here in the presence of a time-varying magnetic field. Thermal conductivity plays a vital role in the cooling rate of the medium or its temperature evolution. The magnetic field produced during the early stages of (non-central) heavy-ion collisions decays with time, where electrical conductivity plays a significant role. As the medium expands, the electrical and thermal properties change, reflecting the effect in various observables. In this study, we have calculated the thermal conductivity of the QGP medium, incorporating the effects of temperature and magnetic field evolution. We discovered that conductivity significantly depends on the cooling rate, and its value increases due to temperature evolution. Furthermore, the influence of these evolutions on the elliptic flow coefficient is measured, and elliptic flow decreases due to the evolution. We also extend our study for the case of Gubser flow, where, along with the longitudinal Bjorken expansion, the radially transverse expansion is also present.
↳ hep-phhep-exnucl-exnucl-thPRD(2024)·17 citations
16
The baryon number fluctuation $κ σ^{2}$ as a probe of nuclear matter phase transition at high baryon density
Kun Xu🇨🇳 · Mei Huang🇨🇳
Two critical end points (CEPs) of the chiral phase transition and the nuclear liquid-gas phase transition show up at finite baryon chemical potential. The kurtosis $κ σ^{2}$ of baryon number fluctuation on the $T - μ_{B}$ plane is positive on the first-order side and negative on the crossover side along the phase boundary. The freeze-out line extracted from the heavy ion collisions crosses between these two phase boundaries, one can observe a peak of $κ σ^{2}$ around the collision energy $5 GeV$ near the CEP of the chiral phase transition, and negative $κ σ^{2}$ at low collision energies due to the CEP of the nuclear liquid-gas phase transition. This expalains the experimental measurement of $κ σ^{2}$ at the collision energies of 2.4 GeV at HADES and 3 GeV and 7.7-200 GeV at STAR for most central collision. Thus we propose that the baryon number fluctuation $κ σ^{2}$ can be used as a probe of nuclear matter phase structure at high baryon density.
↳ hep-phnucl-th3 citations
17
Proton induced reactions on 114Sn and 120Sn targets at energies up to 18 MeV
G.H.Hovhannisyan · T.M.Bakhshiyan · G.V.Martirosyan · R.K.Dallakyan · A.R.Balabekyan
We measure cross sections of proton-induced reactions on tin up to energies of 18 MeV using the stacked-foil activation technique, and report first experimental values for 114Sn(p,{\alpha})111In, {^{120}}Sn(p,{\alpha})117gIn, and 114Sn(p,x)113Sn reactions. Measured cross sections have been compared to existing experimental values and numerical calculations based on Talys1.95. Our data are in good agreement with all previous experiments, and also with Talys1.95 results except for 120Sn(p,{\alpha})117m,gIn reactions where the numerical calculations are shifted to higher energies. We also measure isomeric cross section ratios for 117m,gIn and 120m,gSb pairs as functions of the incident proton energy.
↳ nucl-exnucl-thphysics.app-phEPJA(2023)·1 citation
18
Toward extracting scattering phase shift from integrated correlation function
Peng Guo🇺🇸 · Vladimir Gasparian🇺🇸
In present work, a relation that connects the integrated correlation function of a trapped two-particle system to infinite volume particles scattering phase shift is derived. It has the potential to provide an alternative approach for extracting two-particle scattering phase shift from integrated correlation function in lattice simulation at small Euclidean time region. Both (i) perturbation calculation of 1+1 dimensional lattice Euclidean field theory model of fermions interacting with a contact interaction and (ii) Monte Carlo simulation of a 1D exactly solvable quantum mechanics model are carried out to test the proposed relation. In contrast to conventional two-step approach of extracting energy levels from temporal correlation function in lattice simulation at large Euclidean time first and then applying Lüscher formula to convert energy levels into scattering phase shifts, we show that the difference of integrated correlation functions between interacting and noninteracting trapped systems converges rapidly to infinite volume limit that is given in terms of scattering phase shifts at small Euclidean time region.
↳ hep-lathep-phnucl-thPRD(2023)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE