Nuclear Theory·nucl-th

Thursday·February 9, 2023

7 papers—3 primary·4 cross-listed

01
[Submitted on 8 Feb 2023]
Direct triple- $α$ process in non-adiabatic approach
M. Katsuma
Triple- $α$ reaction rates have been determined well with the sequential process via the narrow resonances. However, the direct triple- $α$ process at off-resonant energies still remains in unsolved problems. In the present report, the direct triple- $α$ contribution is estimated with a non-adiabatic method, and it is found to be 10 $^{- 15}$ --10 $^{- 3}$ pb order in photodisintegration cross sections of $^{12}$ C(2 $_{1}^{+} \to$ 0 $^{+}$ ) for $0.15 < E < 0.35$ MeV. This is far below the values predicted by the recent adiabatic models. In spite of the large difference, the derived rates are found to be concordant with NACRE at the helium burning temperatures.
Comments:
4 pages, 2 figures; Proceedings of 16th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG16), 25-28 October 2022, Hanoi, Vietnam
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2302.03844 [pdf]
1 citation
02
[Submitted on 8 Feb 2023]
Three-dimensional potential energy surface for fission of $^{236}$ U within covariant density functional theory
Ming-Hui Zhou · Ze-Yu Li · Sheng-Yuan Chen · Yong-Jing Chen · Zhi-Pan Li
We have calculated the three-dimensional potential energy surface (PES) for the fission of compound nucleus $^{236}$ U using the covariant density functional theory with constraints on the axial quadrupole and octupole deformations $(β_{2}, β_{3})$ as well as the nucleon number in the neck $q_{N}$ . By considering the additonal degree of freedom $q_{N}$ , coexistence of the elongated and compact fission modes is predicted for $0.9 ≲ β_{3} ≲ 1.3$ . Remarkably, the PES becomes very shallow across a large range of quadrupole and octupole deformations for small $q_{N}$ , and consequently, the scission line in $(β_{2}, β_{3})$ plane will extend to a shallow band, which leads to a fluctuation for the estimated total kinetic energies by several to ten MeV and for the fragment masses by several to about ten nucleons.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.03864 [pdf]
CPC(2023)·3 citations
03
[Submitted on 8 Feb 2023]
Systematic analysis of the impacts of symmetry energy parameters on neutron star properties
N. K. Patra · Anagh Venneti · Sk Md Adil Imam · Arunava Mukherjee · B. K. Agrawal
The impacts of various symmetry energy parameters on the properties of neutron stars (NSs) have been recently investigated, and the outcomes are at variance, as summarized in Table III of Phys. Rev. D 106, 063005 (2022). We have systematically analyzed the correlations of slope and curvature parameters of symmetry energy at the saturation density ( $ρ_{0} = 0.16 fm^{- 3}$ ) with the tidal deformability and stellar radius of non-spinning neutron stars in the mass range of $1.2 - 1.6 M_{⊙}$ using a large set of minimally constrained equations of state (EoSs). The EoSs at low densities correspond to the nucleonic matter and are constrained by empirical ranges of a few low-order nuclear matter parameters from the finite nuclei data and the pure neutron matter EoS from chiral effective field theory. The EoSs at high densities ( $ρ > 1.5 - 2 ρ_{0}$ ) are obtained by a parametric form for the speed of sound that satisfies the causality condition. Several factors affecting the correlations between the NS properties and the individual symmetry energy parameters usually encountered in the literature are considered. These correlations are quite sensitive to the choice of the distributions of symmetry energy parameters and their interdependence. But, variations of NS properties with the pressure of $β -$ equilibrated matter at twice the saturation density remain quite robust which maybe due to the fact that the pressure depends on the combination of multiple nuclear matter parameters that describe the symmetric nuclear matter as well as the density dependence of the symmetry energy. Our results are practically insensitive to the behavior of EoS at high densities.
Comments:
14 pages, 8 figures, 4 tables (Published in PRC)
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2302.03906 [pdf]
PRC(2023)·34 citations
04
[Submitted on 7 Feb 2023] (cross-list from hep-ph)
Hadronic structure on the light-front VII. Pions and kaons and their partonic distributions
Wei-Yang Liu🇺🇸 · Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸
This work is a continuation in our series of papers, that addresses quark models of hadronic structure on the light front, motivated by the QCD vacuum structure and lattice results. The spontaneous breaking of chiral symmetry on the light front, is shown to parallel that in the rest frame, where the non-local instanton induced $^{'}$ t Hooft interaction plays a central role. By rewriting this interaction solely in terms of the good component of the fermionic field, a scalar chiral condensate emerges in the mean-field approximation, which is identical to the one obtained in the rest frame. The pions and kaons emerge as deeply bound Goldstone modes in the chiral limit, with the scalar-isoscalar sigma meson mode as a threshold state with zero binding. We explicitly derive the light front distribution amplitudes (DAs) and partonic functions (PDFs) for these mesons. The DAs and PDFs are in good agreement with those extracted from the QCD instanton vacuum in the rest frame, using the large momentum effective theory (LaMET). The QCD evolved DAs and PDFs compare well with available measurements, as well as recent lattice results.
Comments:
52 pages,16 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2302.03759 [pdf]
PRD(2023)·18 citations
05
[Submitted on 8 Feb 2023] (cross-list from gr-qc)
$g$ -mode of neutron stars in pseudo-Newtonian gravity
Hong-Bo Li · Yong Gao · Lijing Shao · Renxin Xu
The equation of state (EOS) of nuclear dense matter plays a crucial role in many astrophysical phenomena associated with neutron stars (NSs). Fluid oscillations are one of the most fundamental properties therein. NSs support a family of gravity $g$ -modes, which are related to buoyancy. We study the gravity $g$ -modes caused by composition gradient and density discontinuity in the framework of pseudo-Newtonian gravity. The mode frequencies are calculated in detail and compared with Newtonian and general-relativistic (GR) solutions. We find that the $g$ -mode frequencies in one of the pseudo-Newtonian treatments can approximate remarkably well the GR solutions, with relative errors in the order of $1%$ . Our findings suggest that, with much less computational cost, pseudo-Newtonian gravity can be utilized to accurately analyze oscillation of NSs constructed from an EOS with a first-order phase transition between nuclear and quark matter, as well as to provide an excellent approximation of GR effects in core-collapse supernova (CCSN) simulations.
Comments:
14 pages, 13 figures, 6 tables; accepted by PRD
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2302.03856 [pdf]
PRD(2023)·4 citations
06
[Submitted on 8 Feb 2023] (cross-list from hep-ph)
Thermodynamic and hydrodynamic characteristics of interacting system formed in relativistic heavy ion collisions
Xu-Hong Zhang🇨🇳 · Hao-Ning Wang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
To study the energy-dependent characteristics of thermodynamic and hydrodynamic parameters, based on the framework of a multi-source thermal model, we analyze the soft transverse momentum ( $p_{T}$ ) spectra of the charged particles ( $π^{-}$ , $π^{+}$ , $K^{-}$ , $K^{+}$ , $p ˉ$ , and $p$ ) produced in gold-gold (Au-Au) collisions at the center-of-mass energies $s_{N N} = 7.7$ , 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV from the STAR Collaboration and in lead-lead (Pb-Pb) collisions at $s_{N N} = 2.76$ and 5.02 TeV from the ALICE Collaboration. In the rest framework of emission source, the probability density function obeyed by meson momenta satisfies the Bose-Einstein distribution, and that obeyed by baryon momenta satisfies the Fermi-Dirac distribution. To simulate the $p_{T}$ of the charged particles, the kinetic freeze-out temperature $T$ and transverse expansion velocity $β_{T}$ of emission source are introduced into the relativistic ideal gas model. Our results, based on the Monte Carlo method for numerical calculation, show a good agreement with the experimental data. The excitation functions of thermodynamic parameter $T$ and hydrodynamic parameter $β_{T}$ are then obtained from the analyses, which shows an increase tendency from 7.7 GeV to 5.02 TeV in collisions with different centralities.
Comments:
13 pages, 5 figures. International Journal of Modern Physics E, accepted
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2302.03867 [pdf]
IJMPE(2023)·1 citation
07
[Submitted on 8 Feb 2023] (cross-list from hep-ph)
Study of $X (6900)$ with unitarized coupled channel scattering amplitudes
Shi-Qing Kuang🇨🇳 · Qi Zhou🇨🇳 · Di Guo🇨🇳 · Qin-He Yang🇨🇳 · Ling-Yun Dai🇨🇳
In this paper, we study the resonant state $X (6900)$ . The scattering amplitudes of coupled channels, $J / ψ J / ψ$ - $J / ψ ψ (2 S)$ - $J / ψ ψ (3770)$ , are constructed with the interaction of four vector mesons described by effective Lagrangians. The amplitudes are calculated up to one loop, decomposed by partial wave projection, and unitarized by Pad $e ˊ$ approximation. These amplitudes are fitted to the latest experimental data sets of di- $J / ψ$ and $J / ψ ψ (2 S)$ invariant mass spectra of LHCb, CMS, and ATLAS. High-quality solutions are obtained. With these partial wave amplitudes, we extract the pole parameters of the $X (6900)$ . Its quantum number is likely to be $0^{++}$ . According to the pole counting rule as well as analysis of the phase shifts of the partial waves, it supports our previous conclusion that the $X (6900)$ prefers to be a compact tetra-quark.
Comments:
23 pages, 4 figures, add a few discussions
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2302.03968 [pdf]
EPJC(2023)·30 citations

Affiliations

first authorsco-authorsvia INSPIRE

Direct triple-α process in non-adiabatic approach

Three-dimensional potential energy surface for fission of 236U within covariant density functional theory

Systematic analysis of the impacts of symmetry energy parameters on neutron star properties

Hadronic structure on the light-front VII. Pions and kaons and their partonic distributions

g-mode of neutron stars in pseudo-Newtonian gravity

Thermodynamic and hydrodynamic characteristics of interacting system formed in relativistic heavy ion collisions

Study of X(6900) with unitarized coupled channel scattering amplitudes

Affiliations

Direct triple- $α$ process in non-adiabatic approach

Three-dimensional potential energy surface for fission of $^{236}$ U within covariant density functional theory

$g$ -mode of neutron stars in pseudo-Newtonian gravity

Study of $X (6900)$ with unitarized coupled channel scattering amplitudes