Nuclear Theory·nucl-th

Tuesday·February 11, 2025

11 papers—4 primary·7 cross-listed

01
[Submitted on 9 Feb 2025]
An MLE analysis on the relationship between the initial-state granularity and final-state flow factorization
Shui-Fa Shen🇨🇳 · Chong Ye🇨🇳 · Dan Wen🇨🇳 · Lina Bao🇨🇳 · Jin Li🇨🇳 · Yutao Xing🇧🇷 · Jiaming Jiang🇨🇳 · Wei-Liang Qian🇨🇳
In this study, we employ the maximum likelihood estimator (MLE) to investigate the relationship between initial-state fluctuations and final-state anisotropies in relativistic heavy-ion collisions. The granularity of the initial state, reflecting fluctuations in the initial conditions (IC), is modeled using a peripheral tube model. Besides differential flow, our analysis focuses on a class of more sensitive observables known as flow factorization. Specifically, we evaluate these observables using MLE, an asymptotically normal and unbiased tool in standard statistical inference. Our findings show that the resulting differential flow remains essentially unchanged for different IC defined by the peripheral tube model. The resulting harmonic coefficients obtained using MLE and multi-particle cumulants are found to be consistent. However, the calculated flow factorizations show significant variations depending on both the IC and the estimators, which is attributed to their sensitivity to initial-state fluctuations. Thus, we argue that MLE offers a compelling alternative to standard methods such as multi-particle correlators, particularly for sensitive observables constructed from higher moments of the azimuthal distribution.
Comments:
13 pages, 5 figures. arXiv admin note: text overlap with arXiv:2408.14347
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2502.05737 [pdf]
CPC(2025)·2 citations
02
[Submitted on 9 Feb 2025]
Robust linear correlations related to neutron skin thickness
Y. Lei · X. Lian · C. L. Bai
We observe various robust linear correlations related to neutron skin thickness ( $Δ R_{np}$ ) within different interaction ensembles, including newly proposed random Skyrme ensemble. The robust linear correlation between $Δ R_{np}$ , or charge radius difference of mirror nuclei ( $Δ R_{mirr}$ ), and the isospin asymmetry ( $I = \frac{N - Z}{A}$ ) becomes apparent as the model space is enlarged. Shape coexistence, or shape effect on charge radius, is considered to explain the experimental deviation of $^{18}$ O/Ne and some odd- $A$ $Δ R_{mirr}$ s from the $Δ R_{mirr} - I$ linearity. The slopes of the linear $Δ R_{mirr} - I$ and $Δ R_{np} - I$ correlations ( $C_{np}$ and $C_{mirr}$ , respectively) are also robustly and linearly correlated to the slope of the symmetry energy ( $L$ ). These linear correlations are further understood with the similar formulation between between $L$ and the symmetry energy coefficient ( $J$ ). The linear correlations between $C_{np} - L$ and $C_{mirr} - L$ are also adopted to constrain $L$ to $20 \sim 36$ MeV with 1 $σ$ confidence. Considering the deviation of $^{18}$ O/Ne $Δ R_{mi r r}$ due to shape coexistence, the 1 $σ$ range for $L$ is further narrowed to $28 \sim 36$ MeV, suggesting a relatively soft equation of state for nuclear matter.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2502.05820 [pdf]
PRC(2026)·1 citation
03
[Submitted on 10 Feb 2025]
Delta isobar resonance effects studied by summed isospin spin strengths and nuclear matrix elements for double and single beta decays
Hiroyasu Ejiri
Nuclear matrix elements (NMEs) for double and single beta decays are crucial for studying neutrino properties beyond and within the standard model. The NMEs consist mainly of the spin isospin components. The delta isobar resonance, which is strongly excited by the qualk spin isospin excitation, is shown to quench the spin isospin NMEs by a coefficient around 0.7. Impact of the delta resonance on neutrino studies in nuclei is discused.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2502.06122 [pdf]
1 citation
04
[Submitted on 10 Feb 2025]
Octupole correlations in superdeformed bands of $^{56}$ Ni
Xiao Lu · Shivani Jain · Hiroyuki Sagawa · Shan-Gui Zhou
The projected multi-dimensionally-constrained relativistic Hartree-Bogoliubov model was employed to calculate the potential energy surface of the high-spin states in $^{56} Ni$ . It is pointed out for the first time that possible octupole deformations exist for the positive and negative parity superdeformed bands in $^{56} Ni$ , with deformations $β_{30} \sim 0.14$ and $β_{30} \sim 0.24$ , respectively, along with a large prolate deformation of $β_{20} \sim 0.42$ . These octupole deformations are induced by the coupling between $2 p_{3/2}$ and $1 g_{9/2}$ orbits at the deformation $β_{20} \sim 0.4$ . The calculated excitation energies of the two rotational bands are consistent with the observed superdeformed bands of $^{56} Ni$ . In addition, two rotational bands are predicted, consisting of one superdeformed band with negative parity and one hyperdeformed bands with positive parity.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2502.06184 [pdf]
PLB(2025)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

An MLE analysis on the relationship between the initial-state granularity and final-state flow factorization

Robust linear correlations related to neutron skin thickness

Delta isobar resonance effects studied by summed isospin spin strengths and nuclear matrix elements for double and single beta decays

Octupole correlations in superdeformed bands of 56Ni

Affiliations

Octupole correlations in superdeformed bands of $^{56}$ Ni