Nuclear Theory·nucl-th

Tuesday·August 8, 2023

20 papers—11 primary·9 cross-listed

12
A multistage framework for studying the evolution of jets and high- $p_{T}$ probes in small collision systems
Abhijit Majumder · Aaron Angerami · Ritu Arora · Steffen Bass · Shanshan Cao · Yi Chen · Raymond Ehlers · Hannah Elfner · Wenkai Fan · Rainer J. Fries · Charles Gale · Yayun He and 39 other authors
Understanding the modification of jets and high- $p_{T}$ probes in small systems requires the integration of soft and hard physics. We present recent developments in extending the JETSCAPE framework to build an event generator, which includes correlations between soft and hard partons, to study jet observables in small systems. The multi-scale physics of the collision is separated into different stages. Hard scatterings are first sampled at binary collision positions provided by the Glauber geometry. They are then propagated backward in space-time following an initial-state shower to obtain the initiating partons' energies and momenta before the collision. These energies and momenta are then subtracted from the incoming colliding nucleons for soft-particle production, modeled by the 3D-Glauber + hydrodynamics + hadronic transport framework. This new hybrid approach (X-SCAPE) includes non-trivial correlations between jet and soft particle productions in small systems. We calibrate this framework with the final state hadrons' $p_{T}$ -spectra from low to high $p_{T}$ in $p$ - $p$ , and and then compare with the spectra in $p$ - $P b$ collisions from the LHC. We also present results for additional observables such as the distributions of event activity as a function of the hardest jet $p_{T}$ in forward and mid-rapidity for both $p$ - $p$ and $p$ - $P b$ collisions.
↳ hep-phnucl-exnucl-thPoS(2024)·2 citations
13
Early time dynamics and constraints on medium evolution
Kirill Boguslavski🇦🇹
In relativistic heavy-ion collisions, a quark-gluon plasma (QGP) is created whose pre-equilibrium evolution includes a rich variety of exciting phenomena of Quantum Chromodynamics. In these Proceedings, we provide a short overview of our current understanding of the pre-equilibrium dynamics of the QGP from a weak-coupling perspective and highlight recent developments. Focusing on new studies, we then discuss how initial stages of the QGP medium may impact hard probes including direct photons, dileptons, jets, and heavy quarks. This introduces promising opportunities to obtain experimental signatures of the pre-equilibrium QGP.
↳ hep-phhep-exnucl-thPoS(2024)·0 citations
14
Causal and stable first-order chiral hydrodynamics
Nick Abboud🇺🇸 · Enrico Speranza🇺🇸 · Jorge Noronha🇺🇸
We derive the set of inequalities that is necessary and sufficient for nonlinear causality and linear stability of first-order relativistic hydrodynamics with either a $U (1)_{V}$ conserved current or a $U (1)_{A}$ current with a chiral anomaly or both. Our results apply to generic hydrodynamic frames in which no relations among the transport parameters are imposed. Furthermore, our analysis yields, to the best of our knowledge, the first theory of viscous chiral hydrodynamics proven to be causal and stable. We find that causality demands the absence of vorticity-induced heat flux, forcing a departure from the thermodynamic frame in the chiral case. The inequalities for causality and stability define a hypervolume in the space of transport parameters, wherein each point corresponds to a consistent formulation. Notably, causality is determined by just three combinations of transport parameters. We present our results in a form amenable to numerical hydrodynamic simulations.
↳ hep-thgr-qchep-phnucl-thPRD(2024)·32 citations
15
Efficient production of nuclear isomer $^{93 m}$ Mo with laser-accelerated proton beam and an astrophysical implication on $^{92 m}$ Mo production
Wenru Fan · Wei Qi · Jingli Zhang · Zongwei Cao · Haoyang Lan · Xinxiang Li · Yi Xu · Yuqiu Gu · Zhigang Deng · Zhimeng Zhang · Changxiang Tan · Wen Luo · Yun Yuan · Weimin Zhou
Nuclear isomers play a key role in the creation of the elements in the universe and have a number of fascinating potential applications related to the controlled release of nuclear energy on demand. Particularly, $^{93 m}$ Mo isomer is a good candidate for studying the depletion of nuclear isomer via nuclear excitation by electron capture. For such purposes, efficient approach for $^{93 m}$ Mo production needs to be explored. In the present work, we demonstrate experimentally an efficient production of $^{93 m}$ Mo through $^{93}$ Nb(p, n) reaction induced by intense laser pulse. When a ps-duration, 100-J laser pulse is employed, the $^{93 m}$ Mo isomer at 2425 keV (21/2 $^{+}$ , $T_{1/2}$ = 6.85 h) are generated with a high yield of $1.8 \times 1 0^{6}$ particles/shot. The resulting peak efficiency is expected to be $1 0^{17}$ particles/s, which is at least five orders of magnitudes higher than using classical proton accelerator. The effects of production and destruction of $^{93 m}$ Mo on the controversial astrophysical p-isotope $^{92}$ Mo are studied. It is found that the $^{93}$ Nb(p, n)- $^{93 m}$ Mo reaction is an important production path for ^{93m}Mo seed nucleus, and the influence of ^{93m}Mo-^{92}Mo reaction flow on ^{92}Mo production cannot be ignored. In addition, we propose to directly measure the astrophysical rate of (p, n) reaction using laser-induced proton beam since the latter one fits the Maxwell-Boltzmann distribution well. We conclude that laser-induced proton beam opens a new path to produce nuclear isomers with high peak efficiency towards the understanding of p-nuclei nucleosythesis.
↳ nucl-exastro-ph.SRnucl-thphysics.plasm-phPRResearch(2023)·5 citations
16
The effect of initial nuclear deformation on dielectron photoproduction in hadronic heavy-ion collisions
Jiaxuan. Luo🇨🇳 · Xinbai. Li🇨🇳 · Zebo. Tang🇨🇳 · Xin. Wu🇨🇳 · Wangmei. Zha🇨🇳
Significant excesses of $e^{+} e^{-}$ pair production at very low transverse momentum ( $p_{T} <$ 0.15 GeV/c) were observed by the STAR collaboration in hadronic heavy-ion collisions. Such enhancement is assumed to be a sign of photon-photon production in heavy-ion collisions with hadronic overlap, based on comparisons with model calculations for spherical Au + Au collisions. However, there is a lack of calculations for $e^{+} e^{-}$ pair production from coherent photon-photon interactions in hadronic U + U collisions, due to the deformity of Uranium nuclei. In this article, we present calculations for $e^{+} e^{-}$ pair photoproduction at $s_{N N}$ = 193 GeV in both spherical and deformed U + U collisions within STAR detector acceptance using the equivalent photon approximation (EPA). We conduct event-by-event analysis to investigate the effects of initial nuclear deformation on pair production. Our numerical results show good agreement with experimental data for the 40%--60% and 60%--80% centrality classes in U + U collisions, and the differences between spherical and deformed configurations are approximately 3\%. We also calculate the yields of the photoproduced $e^{+} e^{-}$ pair in hadronic deformed Ru + Ru and Zr + Zr collisions at $s_{N N}$ = 200 GeV. The results reveal that the ratios of the yields of Ru to Zr exhibit very small differences ( $<$ 1%) between spherical and deformed cases.
↳ hep-phnucl-thPRC(2023)·12 citations
17
Inelastic and elastic parton scatterings in the strongly interacting quark-gluon plasma
Ilia Grishmanovskii🇩🇪 · Olga Soloveva🇩🇪 · Taesoo Song🇩🇪 · Carsten Greiner🇩🇪 · Elena Bratkovskaya🇩🇪
We investigate the role of inelastic processes in the strongly interacting quark-gluon plasma (sQGP) based on the effective dynamical quasi-particle model (DQPM). In the DQPM the non-perturbative properties of the sQGP at finite temperature $T$ and baryon chemical potential $μ_{B}$ are described in terms of strongly interacting off-shell partons (quarks and gluons) with dynamically generated spectral functions whose properties are adjusted to reproduce the lQCD EoS for the QGP in thermodynamic equilibrium. For the first time the massive gluon radiation processes from the off-shell quark-quark ( $q + q$ ) and quark-gluon ( $q + g$ ) scatterings are calculated explicitly within leading order Feynman diagrams with effective propagators and vertices from the DQPM without any further approximations. We present the results for the energy and temperature dependencies of the total and differential radiative cross sections and compare them to the corresponding elastic cross sections. We show that our results reproduce the pQCD calculations in the limit of zero masses and widths of quasiparticles. Also we study the $μ_{B}$ dependence of the inelastic cross sections. Moreover, we present estimates for the transition rate and relaxation time of radiative versus elastic scatterings in the sQGP.
↳ hep-phnucl-thPRC(2024)·13 citations
18
Bottom-charmed baryons in a nonrelativistic quark model
Qing-Fu Song🇨🇳 · Qi-Fang Lü🇨🇳 · Atsushi Hosaka🇯🇵
In this work, we study the low-lying mass spectra for bottom-charmed baryons in a nonrelativistic quark model by solving the three-body Schrödinger equation. The lowest $Ξ_{b c}$ , $Ξ_{b c}^{'}$ , $Ω_{b c}$ , and $Ω_{b c}^{'}$ states are predicted to be about 6979, 6953, 7109, and 7092 MeV, respectively. Also, the strong decays for the low-lying excited states are investigated. Our results indicate that some of $λ -$ mode $P -$ wave bottom-charmed baryons are relatively narrow, which can be searched for in future experiments. For the low-lying $ρ -$ mode and $ρ - λ$ hybrid states, their strong decays are highly suppressed and they can survive as extremely narrow states. Moreover, the mass spectra and strong decays for bottom-charmed baryons preserve the heavy quark symmetry well. We hope our calculations can provide helpful information for further experimental and theoretical researches.
↳ hep-phhep-exnucl-thEPJC(2024)·7 citations
19
Interpretation of near-threshold peaks using the method of independent S-matrix poles
Leonarc Michelle Santos🇵🇭 · Denny Lane B. Sombillo🇵🇭
We propose a model-independent analysis of near-threshold enhancements using independent S-matrix poles. In this formulation, we constructed a Jost function with controllable zeros to ensure that no poles are generated on the physical Riemann sheet. We show that there is a possibility of misinterpreting the observed near-threshold signals if one utilized a limited parametrization and restrict the analysis to only one element of the S-matrix. Specifically, there is a possibility of the emergence of ambiguous pair of poles which are singularities of the full S-matrix but may not manifest in one of its elements. For a more concrete discussion, we focused on an effective two-channel scattering where the full S-matrix is a $2 \times 2$ matrix. We apply our method to the coupled two-channel analysis of the $P_{ψ}^{N} (4312)^{+}$ and found that the compact pentaquark interpretation cannot be ruled out yet.
↳ hep-phnucl-thPRC(2023)·11 citations
20
Quasiparticle Cosmology
Amaresh Jaiswal🇮🇳
We consider thermodynamics of the Universe within a quasiparticle approach where the collective dynamics of a system is governed by the thermal mass of the constituents. The spacetime dependence of this thermal mass leads to a negative contribution to the pressure and a positive contribution to the energy density, similar to the effect due to dark energy. We propose a mechanism based on thermodynamic arguments to quantify this contribution from the thermal vacuum of the system. For a sufficiently large spacetime variation of the thermal mass, the effective pressure can become negative and could mimic a dark energy equation of state. We validate our framework using results from renormalizable interacting scalar field theory and demonstrate an application on QCD axion.
↳ hep-thgr-qcnucl-thPRD(2024)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE