Nuclear Theory·nucl-th

Tuesday·January 3, 2023

15 papers—9 primary·6 cross-listed

01
[Submitted on 31 Dec 2022]
Collective modes in the anisotropic collisional hot QCD medium at finite chemical potential
Mohammad Yousuf Jamal🇮🇳
We conducted a study on the collective modes within the hot QCD medium generated in heavy-ion collision experiments. These modes, whether real or imaginary, stable or unstable, play a crucial role in shaping the medium's evolution. To gain a deeper understanding, we considered several factors affecting the medium, including anisotropy, interactions among medium particles, and finite baryonic chemical potential. While the first two aspects have been thoroughly examined from various angles, the inclusion of finite chemical potential was previously overlooked. To provide a comprehensive analysis, we integrated these factors. The interactions among medium particles were accounted for using the BGK collisional kernel, while anisotropy and finite chemical potential were incorporated through the distribution functions of quarks, anti-quarks, and gluons. Our findings suggest that the presence of finite chemical potential amplifies the influence of unstable modes, potentially affecting the rapid thermalization of the hot QCD medium. Furthermore, exploring the implications of finite chemical potential in conjunction with other aspects of the created medium is intriguing, particularly in the context of low-energy heavy-ion collision experiments conducted at low temperatures and finite baryon density.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2301.00187 [pdf]
Eur.Phys.J.Plus(2024)·3 citations
02
[Submitted on 31 Dec 2022]
A transport model description of Time-Dependent Generator Coordinate under Gaussian overlap approximation
Fangyuan Wang · Yingxun Zhang · Zhipan Li
In this work, we derived a transport equation based on a generalized equation of time-dependent generator coordinate method (TDGCM) under the Gaussian overlap approximation (GOA). The transport equation is obtained by using quantum-mechanics phase space distributions under a ``quasi-particle" picture and strategy of Bogoliubov-Born-Green-Kirkood-Yvon (BBGKY) hierarchy. The theoretical advantage of this transport equation is that time evolution of $s$ -body phase space density distribution is coupled with $s + 1$ -body phase space density distributions, and thus, non-adiabatic effects and dynamical fluctuations could be involved by more collective degrees and entanglement of phase space trajectories. In future, we will perform the numerical calculations for fission nuclei after obtaining collective inertia and potential energy surface (PES).
Comments:
11 pages, 0 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2301.00202 [pdf]
0 citations
03
[Submitted on 31 Dec 2022]
How Do Constraints of Nuclear Symmetry Energy Reconcile with Different Models?
Yingxun Zhang · Yangyang Liu · Yongjia Wang · Qingfeng Li · Zhuxia Li
By simultaneously describing the data of isospin sensitive nucleonic flow and pion observables, such as $v_{2}^{n} / v_{2}^{c h}$ and $π^{-} / π^{+}$ , with ultra-relativistic quantum molecular dynamics (UrQMD) model, we got the symmetry energy at flow and pion characteristic densities which are $S (1.2 ρ_{0}) = 34 \pm 4$ MeV and $S (1.5 ρ_{0}) = 36 \pm 8$ MeV. Within the uncertainties, the constraints of symmetry energy at characteristic densities are consistent with the previous constraints by using other transport models. The consistency suggests that the reliable constraints on symmetry energy should be presented at the characteristic density of isospin sensitive observables. By using the constraints of symmetry energy at two different characteristic densities, the extrapolated value of $L$ is provided. Within $2 σ$ uncertainty, the extrapolated value of $L$ is in $5 - 70$ MeV which is consistent with the recent combination analysis from PREX-II and astrophyiscs data. Further, the calculations with the constrained parameter sets can describe the data of charged pion multiplicities from S $π$ RIT collaboration.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2301.00212 [pdf]
2 citations
04
[Submitted on 31 Dec 2022]
Cluster radioactivity in trans-lead region: A systematic study with modified empirical formulas
A. Jain · P. K. Sharma · S. K. Jain · J. K. Deegwal · G. Saxena
The possibility of cluster emission from trans-lead (86 $\leq$ Z $\leq$ 96) region of periodic chart has been explored comprehensively by employing few empirical formulas which are modified by adding angular momentum ( $l$ ) or isospin-dependent ( $I = (N - Z) / A$ ) or both terms for the calculation of cluster decay half-lives. These modified versions of the formulas are found with lesser $χ^{2}$ per degree of freedom and root mean-square error, in addition to the smaller values of some other statistical parameters, while compared to their corresponding old versions on available 61 experimental data of cluster radioactivity. By applying the modified version of the formula given by Balasubramaniam \textit{et al.} [PRC 70 (2004) 017301], the most accurate formula among these, half-lives of several clusters i.e. isotopes of Be, B, C, N, O, F, Ne, Na, Mg, and Si are predicted systematically for the several isotopes in the trans-lead region. The contest of cluster emission with $α$ -decay has been investigated in form of branching ratio which brings several potential cluster emissions into the probable decay modes of these nuclei. The accurate prediction of half-lives of such clusters is expected to be crucial for the future experimental observations where $α$ -decay is observed dominantly.
Comments:
13 pages, 2 figures, Accepted in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2301.00261 [pdf]
NPA(2023)·14 citations
05
[Submitted on 2 Jan 2023]
Analytical comparison between X(3) and X(5) models of the Bohr Hamiltonian
Kayode Richard Ajulo · Kayode John Oyewumi
The 3-D Bohr-Mottelson Hamiltonian for $γ$ -rigid prolate isotopes, known as $X (3)$ , is solved via inverse square potential having only one free parameter, $β_{0}$ . The exact form of the wave functions and the energy spectra are obtained as a function of the free parameter of the potential that determines the changes in the spectra ratios and the $B (E 2)$ . Since $X (3)$ is an exactly separable $γ$ -rigid version of $X (5)$ , the solutions are compared with the $X (5)$ model and some new set of equations that show the relationships between the two models are stated. In other to show the dynamical symmetry nature of the solutions, the entire solutions from $β_{0} = 0$ to $β_{0} = \infty$ are compared with $U (5)$ , $X (5)$ and $S U (3)$ . The solutions spread from the region around $U (5)$ over $X (5)$ and approach $S U (3)$ at $β_{0} = \infty$ . The exact solutions obtained via variational procedure are compared favourably with some existing $X (3)$ models found in the literature. The strong agreement between the present model and $X (3)$ via infinite square well potential is discussed. Twelve best critical point isotopes, $^{102}$ Mo, $^{104 - 108}$ Ru, $^{120 - 126}$ Xe, $^{148}$ Nd, $^{184 - 188}$ Pt are chosen for experimental realization of the model and moderate agreements are recorded. An excellent agreement which appears in the first $β$ -excited state in the comparison of the present model with three $N = 90$ isotones: $^{150}$ Nd, $^{154}$ Gd, and $^{156}$ Dy, known to be $X (5)$ candidates, suggests that the present model compensates the $X (5)$ models whose predictions are excellent in the ground states but moderately bad in the first $β$ -excited states.
Comments:
15 pages, 3 figures, 7 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2301.00533 [pdf]
Heliyon(2024)·0 citations
06
[Submitted on 2 Jan 2023]
Relativistic BGK hydrodynamics
Pracheta Singha🇮🇳 · Samapan Bhadury🇮🇳 · Arghya Mukherjee🇨🇦 · Amaresh Jaiswal🇮🇳
Bhatnagar-Gross-Krook (BGK) collision kernel is employed in the Boltzmann equation to formulate relativistic dissipative hydrodynamics. In this formulation, we find that there remains freedom of choosing a matching condition that affects the scalar transport in the system. We also propose a new collision kernel which, unlike BGK collision kernel, is valid in the limit of zero chemical potential and derive relativistic first-order dissipative hydrodynamics using it. We study the effects of this new formulation on the coefficient of bulk viscosity.
Comments:
16 pages, 4 figures, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
2301.00544 [pdf]
EPJC(2024)·10 citations
07
[Submitted on 2 Jan 2023]
Hydrodynamic model of heavy-ion collisions with low momentum components
Akihiko Monnai🇯🇵
Relativistic heavy-ion collisions suggest that low momentum regions of the observed particle spectra are thermal and hydrodynamic, while medium-high momentum regions are non-thermal and perturbative. In this study, I construct a hydrodynamic model of heavy-ion collisions by cutting off the medium-high momentum contributions and investigate the phenomenological consequences. Numerical simulations indicate that the temperature of the quark matter can be higher at earlier times owing to the modification of the equation of state. It is also suggested that direct photon elliptic flow can be sensitive to the momentum dependence of thermalization.
Comments:
17 pages, 5 figures; revised version to appear in Journal of Physics G: Nuclear and Particle Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2301.00588 [pdf]
J.Phys.G(2023)·2 citations
08
[Submitted on 2 Jan 2023]
Investigating the Role of Electric Fields on Flow Harmonics in Heavy-Ion Collisions
Ankit Kumar Panda🇮🇳 · Reghukrishnan Gangadharan🇮🇳 · Victor Roy🇮🇳
Using the blast-wave model, we explore the effect of electric fields on spectra and flow harmonics (especially the elliptic flow) for charged pions and protons. We incorporate the first-order correction to the single-particle distribution function due to the electric fields and the dissipative effect while calculating the invariant yields of hadron in the Cooper-Frey prescription at the freezeout hypersurface. We find a noticeable correction to the directed and elliptic flow of pions and protons for unidirectional and azimuthal asymmetric electric fields in the transverse plane of magnitude $\sim m_{π}^{2}$ . Further, we observe mass dependency of the directed flow generated due to the electric fields. The splitting of particle and antiparticle's elliptic flow is also discussed.
Comments:
10 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2301.00632 [pdf]
J.Phys.G(2023)·11 citations
09
[Submitted on 2 Jan 2023]
Hyperon-nucleon interaction in chiral effective field theory at next-to-next-to-leading order
Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪 · Andreas Nogga🇩🇪 · Hoai Le🇩🇪
A hyperon-nucleon potential for the strangeness $S = - 1$ sector ( $Λ N$ , $Σ N$ ) up to third order in the chiral expansion is presented. SU(3) flavor symmetry is imposed for constructing the interaction, however, the explicit SU(3) symmetry breaking by the physical masses of the pseudoscalar mesons and in the leading-order contact terms is taken into account. A novel regularization scheme is employed which has already been successfully used in studies of the nucleon-nucleon interaction within chiral effective field theory up to high orders. An excellent description of the low-energy $Λ p$ , $Σ^{-} p$ and $Σ^{+} p$ scattering data is achieved. New data from J-PARC on angular distributions for the $Σ N$ channels are analyzed. Results for the hypertriton and $A = 4$ hyper-nuclear separation energies are presented. An uncertainty estimate for the chiral expansion is performed for selected hyperon-nucleon observables.
Comments:
30 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2301.00722 [pdf]
EPJA(2023)·71 citations

Affiliations

first authorsco-authorsvia INSPIRE