Nuclear Theory·nucl-th

Tuesday·March 14, 2023

10 papers—7 primary·3 cross-listed

01
[Submitted on 11 Mar 2023]
Mixing of one-particle-one-hole projected states with the variation after projection wave functions
Xiao Lu · Zhan-Jiang Lian · Zao-Chun Gao
In this paper, we study the mixing of one-particle-one-hole projected states with the variation after projection (VAP) wave functions in attempt to improve the approximation of this method. It turns out that when minimizing only the lowest (yrast) energy with given spin and parity, the one-particle-one-hole projected states can not be mixed into the converged VAP wave function, which is very similar to the situation of the Hartree-Fock method. However, if one minimizes the sum of several lowest energies with the same spin and parity, the one-particle-one-hole mixing can make some improvements to the VAP wave functions. We expect such one-particle-one-hole mixing may be useful in the calculations of the low-lying excited states in heavy nuclei with a large model space.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.06518 [pdf]
PRC(2023)·3 citations
02
[Submitted on 11 Mar 2023]
Removal of $K$ -mixing in angular momentum projected nuclear wave functions
Xiao Lu · Zhan-Jiang Lian · Zao-Chun Gao
Angular momentum projection plays a key role in studying quantum many-body systems with rotational invariance such as atomic nuclei. At a given spin $J$ , one can generate $2 J + 1$ angular momentum projected states labeled with $- J \leq K \leq J$ from a deformed Slater determinant. Usually, a nuclear wave function with $K$ -mixing can be expressed as a superposition of all these $2 J + 1$ projected states, where the coefficients can be obtained by solving the generalized eigenvalue equation. In this Letter, we report a new fundamental feature that the frequently discussed $K$ -mixing in the angular momentum projected nuclear wave function can be safely removed. Strikingly, we found that such nuclear wave function with $K$ -mixing can always be equivalently replaced by a single projected state with any given $K$ . Consequently, such nuclear wave function can be significantly simplified, especially for high-spin states. This also indicates that the $K$ -mixing in the angular momentum projected nuclear wave functions, adopted by many present-day nuclear models, does not carry any physical meaning, and is essentially different from that $K$ -mixing caused by the Coriolis force in the cranked shell model.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.06521 [pdf]
PRC(2025)·1 citation
03
[Submitted on 12 Mar 2023]
Finding the best basis states for the variation after projection nuclear wave functions
Xiao Lu · Zhan-Jiang Lian · Xue-Wei Li · Zao-Chun Gao · Yong-Shou Chen
The variation after projection (VAP) method is expected to be an efficient way of getting the optimized nuclear wave functions, so that they can be as close as possible to the exact shell model ones. However, we found there are two additional problems that may seriously affect the convergence of the VAP iteration. The first problem is, if a randomly selected projected basis state does not mix with a VAP wave function in the VAP calculation, then it is likely that this basis state will never mix with the VAP wave function even after the VAP iteration converges, which means such selected projected basis state is useless. The other problem is the poor orthonormality among the projected basis states that seriously affect the accuracy of the calculated VAP wave function. In the present work, solutions for these two problems are proposed and some examples are presented to test the validity. It turns out that, with the present solutions, the most important projected basis states can be reliably obtained and the fully optimized VAP wave functions can be accurately and efficiently calculated.
Comments:
7 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.06525 [pdf]
CPC(2023)·4 citations
04
[Submitted on 12 Mar 2023]
Single-Particle Spectra in Relativistic Heavy-Ion Collisions Within the Thermal Quantum Field Theory
Dmitry Anchishkin🇺🇦
A quantum generalization of the Cooper-Fry recipe is proposed. The single-particle spectrum arising from relativistic collisions of particles and nuclei is calculated within the thermal quantum field theory framework. The starting point of consideration is the solution of the initial-value problem of particle emission from a space-like hypersurface. In the following steps, we obtain the single-particle spectrum using the ``smaller'' Green's function associated with the fireball medium. Based on this result, several specific examples of particle emission are considered.
Comments:
28 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Quantum Physics (quant-ph)
arXiv:
2303.06655 [pdf]
J.Phys.G(2022)·1 citation
05
[Submitted on 13 Mar 2023]
Sr isotopes: the interplay between shape coexistence and quantum phase transitions
Esperanza Maya-Barbecho · José-Enrique García-Ramos
In this contribution we study the even-even Sr isotopes considering the influence of particle-hole intruder states. We find that the rapid onset of deformation at A $= 98$ and onwards can be explained by the crossing of regular and intruder states. We compare the systematics of Sr with the ones of Zr, Pt, and Hg nuclei
Comments:
To appear in the EUNPC 2022 proceedings
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.07040 [pdf]
EPJ Web Conf.(2023)·0 citations
06
[Submitted on 13 Mar 2023]
Non-radial oscillations and gravitational wave emission of hybrid neutron stars
Zi-Yue Zheng🇨🇳 · Ting-Ting Sun🇨🇳 · Huan Chen🇨🇳 · Jin-Biao Wei🇨🇳 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹
We investigate non-radial oscillations of pure and hybrid neutron stars, employing equations of state of nuclear matter from Brueckner-Hartree-Fock theory, and of quark matter from the Dyson-Schwinger quark model, performing a Gibbs construction for the mixed phase in hybrid stars. Characteristic differences between neutron-star and hybrid-star $g_{1}$ -mode oscillation frequencies, damping times, and gravitational wave strains are pointed out. Prospects of observations are also discussed.
Comments:
11 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2303.07086 [pdf]
PRD(2023)·17 citations
07
[Submitted on 13 Mar 2023]
Constraint of the Nuclear Dissipation Coefficient in Fission of Hypernuclei
J. L. Rodríguez-Sánchez🇪🇸 · J. Cugnon🇧🇪 · J.-C. David🇫🇷 · J. Hirtz🇫🇷 · A. Kelić-Heil🇩🇪 · I. Vidaña🇮🇹
Experimental studies of nuclear fission induced by fusion, transfer, spallation, fragmentation, and electromagnetic reactions in combination with state-of-the-art calculations are successful to investigate the nuclear dissipation mechanism in normal nuclear matter, containing only nucleons. The dissipation mechanism has been widely studied by the use of many different fission observables and nowadays the dissipation coefficients involved in transport theories are well constrained. However, the existence of hypernuclei and the possible presence of hyperons in neutron stars make it necessary to extend the investigation of the nuclear dissipation coefficient to the strangeness sector. In this Letter, we use fission reactions of hypernuclei to constrain for the first time the dissipation coefficient in hypernuclear matter, observing that this coefficient increases a factor of 6 in presence of a single $Λ$ -hyperon with respect to normal nuclear matter.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.07323 [pdf]
PRL(2023)·14 citations
08
[Submitted on 11 Mar 2023] (cross-list from astro-ph.HE)
The study of r-process nucleosynthesis in binary neutron star mergers: Nucleonic weak interactions and nuclear uncertainties
Ina K. B. Kullmann🇺🇸
A long-standing scientific puzzle has been to explain the origin of the heaviest elements in the Universe and, more particularly, the production of the elements heavier than iron up to uranium. The rapid neutron capture process (or r-process) is known to synthesize about 50\% of these heavy elements and the long-lived actinides observed in our solar system and so-called metal-poor r-process-enhanced stars. This thesis aims to study the r-process nucleosynthesis and some of the uncertainties that still govern our predictions, namely, nuclear yields and heating rates. Our focus will be on the r-process in neutron star (NS) mergers, which is in the spotlight after recent ``multi-messenger'' observations, including the combined detection of gravitational waves from a NS-NS merger event and its subsequent electromagnetic counterpart. In this work, we base our nucleosynthesis calculations on hydrodynamical simulations of NS merger systems, which estimate the amount of ejected mass and its properties during ejection. Through our r-process calculations, we estimate the composition of this gravitationally unbound material, which can contribute to the r-process enrichment of the Galaxy. This work is divided into two studies, each addressing a remaining open question regarding the r-process nucleosynthesis. First, a coherent study of the impact of neutrino interactions on the r-process element nucleosynthesis and the heating rate produced by the radioactive decay of nuclei synthesized in the dynamical ejecta of NS-NS mergers is presented. We have studied the material ejected from four NS-NS merger systems based on hydrodynamical simulations...
Comments:
PhD thesis, 214 pages, 82 figures, 8 tables. arXiv admin note: text overlap with arXiv:2207.07421
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2303.06366 [pdf]
https://difusion.ulb.ac.be/vufind/Record/…·0 citations
09
[Submitted on 12 Mar 2023] (cross-list from hep-ph)
High energy nuclear physics meets Machine Learning
Wan-Bing He🇨🇳 · Yu-Gang Ma🇨🇳 · Long-Gang Pang🇨🇳 · Huichao Song🇨🇳 · Kai Zhou🇩🇪
Though being seemingly disparate and with relatively new intersection, high energy nuclear physics and machine learning have already begun to merge and yield interesting results during the last few years. It's worthy to raise the profile of utilizing this novel mindset from machine learning in high energy nuclear physics, to help more interested readers see the breadth of activities around this intersection. The aim of this mini-review is to introduce to the community the current status and report an overview of applying machine learning for high energy nuclear physics, to present from different aspects and examples how scientific questions involved in high energy nuclear physics can be tackled using machine learning.
Comments:
30 pages, 20 figures, mini-review
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2303.06752 [pdf]
Nucl.Sci.Tech.(2023)·105 citations
10
[Submitted on 13 Mar 2023] (cross-list from hep-ph)
Compositeness of $T_{cc}$ and $X (3872)$ by considering decay and coupled-channels effects
Tomona Kinugawa🇯🇵 · Tetsuo Hyodo🇯🇵
The compositeness of weakly bound states is discussed using the effective field theory from the viewpoint of the low-energy universality. We introduce a model with coupling of the single-channel scattering to the bare state, and study the compositeness of the bound state by varying the bare state energy. In contrast to the naive expectation that the near-threshold states are dominated by the molecular structure, we demonstrate that a non-composite state can always be realized even with a small binding energy. At the same time, however, it is shown that a fine tuning is necessary to obtain the non-composite weakly bound state. In other words, the probability of finding a model with the composite dominant state becomes larger with the decrease of the binding energy in accordance with the low-energy universality. For the application to exotic hadrons, we then discuss the modification of the compositeness due to the decay and coupled-channels effects. We quantitatively show that these contributions suppress the compositeness, because of the increase of the fraction of other components. Finally, as examples of near-threshold exotic hadrons, the structures of $T_{cc}$ and $X (3872)$ are studied by evaluating the compositeness. We find the importance of the coupled-channels and decay contributions for the structures of $T_{cc}$ and $X (3872)$ , respectively.
Comments:
19 pages, 14 figures, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2303.07038 [pdf]
PRC(2024)·38 citations

Affiliations

first authorsco-authorsvia INSPIRE