Nuclear Theory·nucl-th

Tuesday·January 3, 2023

15 papers—9 primary·6 cross-listed

01
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.
nucl-thhep-phEur.Phys.J.Plus(2024)·3 citations
02
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).
nucl-th0 citations
03
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.
nucl-thnucl-ex2 citations
04
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.
nucl-thNPA(2023)·14 citations
05
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.
nucl-thHeliyon(2024)·0 citations
06
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.
nucl-thhep-phhep-thEPJC(2024)·10 citations
07
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.
nucl-thhep-phnucl-exJ.Phys.G(2023)·2 citations
08
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.
nucl-thJ.Phys.G(2023)·11 citations
09
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.
nucl-thhep-exhep-lathep-ph+1EPJA(2023)·71 citations
10
Velocity Laws for Bound States in Asymptotically AdS Geometries
Dimitrios Giataganas🇹🇼
We study the behavior of heavy quark bound states in moving plasmas that are dual to theories with generic non-trivial renormalization group flows interpolating between an AdS geometry in the ultraviolet and infrared fixed points with broken symmetries. We investigate analytically the observables associated with the bound state and find their scaling exponents with respect to the Lorentz factor for ultrarelativistic motion. Despite having asymptotically an AdS geometry, the scaling is not universal and depends on geometric conditions of the Fefferman-Graham expansion in the near boundary regime, or equivalently on the order of the asymptotic background expansion that provides the leading contributions to the Wilson loops.
↳ hep-thhep-phnucl-thFortsch.Phys.(2023)·2 citations
11
Quark spectral functions from spectra of mesons and vice versa
Vladimir Sauli🇨🇿
We extract the spectral function of quarks using the QCD functional formalism.The reliability of approximations is controlled by the masses and decays of pseudoscalar mesons. For light quarks, we select the pion; for charm quarks, we choose the ground and excited states of the $η_{c}$ meson. To this end, we solved the ladder-rainbow approximation of the spectral Dyson-Schwinger equations for quarks coupled to the Bethe-Salpeter equation for the pion and pseudoscalar charmonia. The obtained dynamical charm mass function varies from 1 to 1.5 GeV in the timelike domain, which is significant for narrow charmonium states. This yields a notable response in the bound state spectrum. We obtained purely continuous spectral functions and discussed their connection with confinement.
↳ hep-phnucl-th4 citations
12
Many-body collective neutrino oscillations: recent developments
Amol V. Patwardhan🇺🇸 · Michael J. Cervia🇺🇸 · Ermal Rrapaj🇺🇸 · Pooja Siwach🇺🇸 · A. B. Balantekin🇺🇸
Neutrino flavor transformations in core-collapse supernovae and binary neutron star mergers represent a complex and unsolved problem that is integral to our understanding of the dynamics and nucleosynthesis in these environments. The high number densities of neutrinos present in these environments can engender various collective effects in neutrino flavor transformations, driven either by neutrino-neutrino coherent scattering, or in some cases, through collisional (incoherent) interactions. An ensemble of neutrinos undergoing coherent scattering among themselves is an interacting quantum many-body system -- as such, there is a tantalising prospect of quantum entanglement developing between the neutrinos, which can leave imprints on their flavor evolution histories. Here, we seek to summarize recent progress that has been made towards understanding this phenomenon.
↳ hep-phastro-ph.HEnucl-thquant-phIn: Handbook of Nuclear Physics (2022), S…·26 citations
13
Strange Stars within Bosonic and Fermionic Admixed Dark Matter
Luiz L. Lopes🇧🇷 · H. C. Das🇮🇳
In this work, we study dark matter (DM) admixed strange quark stars exploring the different possibilities about the nature of the DM and their effects on the macroscopic properties of strange stars, such as maximum masses, radii, as well the dimensionless tidal parameter. We observe that the DM significantly affects the macroscopic properties that depend on its mass, type, and fraction inside the star.
↳ astro-ph.HEgr-qchep-phnucl-thJCAP(2023)·23 citations
14
Tribaryons with lattice QCD and one-boson exchange potentials
Tian-Wei Wu🇨🇳 · Si-Qiang Luo🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳 · Xiang Liu🇨🇳
Motivated by the existence of two-body hadronic molecules composed of $ΩΩ$ , $Ω_{ccc} Ω_{ccc}$ and $Ω_{bbb} Ω_{bbb}$ predicted by lattice QCD simulations, we use the Gaussian expansion method to investigate whether three-body systems composed of $ΩΩΩ$ , $Ω_{ccc} Ω_{ccc} Ω_{ccc}$ and $Ω_{bbb} Ω_{bbb} Ω_{bbb}$ can bind with the two-body $^{1} S_{0}$ interactions provided by lattice QCD. Our results show that none of the three-body systems bind. On the other hand, we find that with the one-boson exchange potentials the $ΩΩΩ$ system develops a bound state, for which the $^{5} S_{2}$ interaction plays an important role. Our studies support the existence of the $\frac{3}{2}^{+}$ $ΩΩΩ$ bound state and the nonexistence of the $\frac{3}{2}^{+}$ $Ω_{ccc} Ω_{ccc} Ω_{ccc}$ and $Ω_{bbb} Ω_{bbb} Ω_{bbb}$ bound states, due to the suppressed $^{5} S_{2}$ interactions in heavier systems.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2023)·5 citations
15
Multicomponent Van der Waals model of a nuclear fireball in the freeze-out stage
Ya. D. Krivenko-Emetov (National Technical University of Ukraine - Igor Sikorsky Kyiv Polytechnic Institute, Kyiv, Ukraine)🇺🇦
A two-component van der Waals gas model is proposed to describe the hadronic stages of the evolution of a nuclear fireball in the cooling stage. At the first stage of hadronization, when mesons dominate, a two-component meson model ( $π^{0}$ and $π^{+}$ -mesons) with an effective two-particle interaction potential of a rectangular well is proposed. At the late-stage hadronization, when almost all mesons have decayed, a two-component nucleon model of protons and neutrons is proposed with the corresponding effective rectangular nucleon potential. The saddle point method has been applied for analytical calculations of the partition function. This made it possible to uniformly obtain analytical expressions for both the pressure and density, taking into account the finite dimensions of the system, and the analytical expressions for chemical potentials. It is assumed that the proposed models and derived formulas can be used to analyze experimental data connected to the quantitative characteristics of the particle yields of different types in the final state from the hadronic stages of the evolution of a nuclear fireball, as well as to determine the critical parameters of the system in high-energy nucleus-nucleus collisions.
↳ hep-phnucl-thLHEP(2023)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE