Nuclear Theory·nucl-th

Tuesday·July 2, 2024

22 papers—6 primary·16 cross-listed

01
In-Medium Similarity Renormalization Group at Finite Temperature
Isaac G. Smith · Heiko Hergert · Scott K. Bogner
The study of nuclei at finite temperature is of immense interest for many areas of nuclear astrophysics and nuclear-reaction science. A variety of ab initio methods are now available for computing the properties of nuclei from interactions rooted in Quantum Chromodynamics, but applications have largely been limited to zero temperature. In the present work, we extend one such method, the In-Medium Similarity Renormalization Group (IMSRG), to finite temperature. Using an exactly-solvable schematic model that captures essential features of nuclear interactions, we show that the FT-IMSRG can accurately determine the energetics of nuclei at finite temperature, and we explore the accuracy of the FT-IMSRG in different parameter regimes, e.g., strong and weak pairing. In anticipation of FT-IMSRG applications for finite nuclei and infinite matter, we discuss differences arising from the choice of working with the canonical and the grand canonical ensembles. In future work, we will apply the FT-IMSRG with realistic nuclear interactions to compute nuclear structure and reaction properties at finite temperature, which are important ingredients for understanding nucleosynthesis in stellar environments, or modeling reactions of hot compound nuclei.
nucl-thPRC(2025)·1 citation
02
Mechanisms of mirror energy difference for states exhibiting Thomas-Ehrman shift: Gamow shell model case studies of $^{18}$ Ne/ $^{18}$ O and $^{19}$ Na/ $^{19}$ O
J.G. Li · K. H. Li · N. Michel · H. H. Li · W. Zuo
The mirror energy difference (MED) of the mirror state, especially for states bearing the Thomas-Erhman shift, serves as a sensitive probe of isospin symmetry breaking. We employ the Gamow shell model, which includes the inter-nucleon correlation and continuum coupling, to investigate the MED for $s d$ -shell nuclei by taking the $^{18}$ Ne/ $^{18}$ O and $^{19}$ Na/ $^{19}$ O as examples. Our GSM provides good descriptions for the excitation energies and MEDs for the $^{18}$ Ne/ $^{18}$ O and $^{19}$ Na/ $^{19}$ O. Moreover, our calculations also reveal that the large MED of the mirror states is caused by the significant occupation of the weakly bound or unbound $s_{1/2}$ waves, giving the radial density distribution of the state in the proton-rich nucleus more extended than that of mirror states in deeply-bound neutron-rich nuclei. Furthermore, our GSM calculation shows that the contribution of Coulomb is different for the low-lying states in proton-rich nuclei, which significantly contributes to MEDs of mirror states. Moreover, the contributions of the nucleon-nucleon interaction are different for the mirror state, especially for the state of proton-rich nuclei bearing the Thomas-Erhman shift, which also contributes to the significant isospin symmetry breaking with large MED.
nucl-thnucl-exNucl.Sci.Tech.(2026)·4 citations
03
Applying Deep Learning Technique to Chiral Magnetic Wave Search
Yuan-Sheng Zhao🇨🇳 · Xu-Guang Huang🇨🇳
The chiral magnetic wave (CMW) is a collective mode in quark-gluon plasma originated from the chiral magnetic effect (CME) and chiral separation effect. Its detection in heavy-ion collisions is challenging due to significant background contamination. In Ref.[1], we have constructed a neural network which can accurately identify the CME-related signal from the final-state pion spectra. In this paper, we generalize such a neural network to the case of CMW search. We show that, after a updated training, the neural network can effectively recognize the CMW-related signal. Additionally, we assess the performance of the neural network compared to other known methods for CMW search.
nucl-thnucl-exCPC(2024)·0 citations
04
Three-Nucleon Correlations in Light Nuclei Yields Ratios from AMPT Model for QCD Critical Point Investigation
Ning Yu🇨🇳 · Zuman Zhang🇨🇳 · Hongge Xu🇨🇳 · Zhong Zhu🇨🇳
This research use the AMPT model in Au+Au collisions to study the influence of the three nucleons correlation $C_{n^{2} p}$ on the light nuclei yield ratios. It is found that neglecting $C_{n^{2} p}$ leads to an overestimated relative neutron density fluctuation extraction. Including $C_{n^{2} p}$ will enhances the agreement with experimental results with higher yield ratios, yet it does not change the energy dependence of the yield ratio. Since there is no first-order phase transition or critical physics in the AMPT model, our work fails to reproduce the experimental energy-dependent peak around $s_{NN} =$ 20-30 GeV. Our work might offer a baseline for investigating critical physics phenomena using the light nuclei production as a probe.
nucl-thCPC(2025)·0 citations
05
Deuteron-proton backward elastic scattering at GeV energies
Nadezhda Ladygina
Deuteron-proton elastic scattering is considered at the energies from 880 MeV to 2 GeV at the scattering angles $θ^{*} \geq 14 0^{\circ}$ . The multiple-scattering method is used to calculate the reaction amplitude. Four reaction mechanisms are taken into account: one-nucleon-exchange, single-scattering, and double-scattering with a nucleon and a delta-isobar in the intermediate state. The method allows calculating both unpolarized differential cross section and any polarization observables. All the results obtained are compared to the experimental data.
nucl-thSciPost Phys.Proc.(2020)·3 citations
06
Ab initio description of monopole resonances in light- and medium-mass nuclei: IV. Angular momentum projection and rotation-vibration coupling
Andrea Porro🇩🇪 · Thomas Duguet🇫🇷 · Jean-Paul Ebran🇫🇷 · Mikael Frosini🇫🇷 · Robert Roth🇩🇪 · Vittorio Somà🇫🇷
Giant Resonances are, with nuclear rotations, the most evident expression of collectivity in finite nuclei. These two categories of excitations, however, are traditionally described within different formal schemes, such that vibrational and rotational degrees of freedom are separately treated and coupling effects between those are often neglected. The present work puts forward an approach aiming at a consitent treatment of vibrations and rotations. Specifically, this paper is the last in a series of four dedicated to the investigation of the giant monopole resonance in doubly open-shell nuclei via the ab initio Projected Generator Coordinate Method (PGCM). The present focus is on the treatment and impact of angular momentum restoration within such calculations. The PGCM being based on the use of deformed mean-field states, the angular-momentum restoration is performed when solving the secular equation to extract vibrational excitations. In this context, it is shown that performing the angular momentum restoration only after solving the secular equation contaminates the monopole response with an unphysical coupling to the rotational motion, as was also shown recently for (quasi-particle) random phase approximation calculations based on a deformed reference state. Eventually, the present work based on the PGCM confirms that an a priori angular momentum restoration is necessary to handle consistently both collective motions at the same time. This further pleads in favor of implementing the full-fledged projected (quasi-particle) random phase approximation in the future.
nucl-thEPJA(2024)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

In-Medium Similarity Renormalization Group at Finite Temperature

Mechanisms of mirror energy difference for states exhibiting Thomas-Ehrman shift: Gamow shell model case studies of 18Ne/18O and 19Na/19O

Applying Deep Learning Technique to Chiral Magnetic Wave Search

Three-Nucleon Correlations in Light Nuclei Yields Ratios from AMPT Model for QCD Critical Point Investigation

Deuteron-proton backward elastic scattering at GeV energies

Ab initio description of monopole resonances in light- and medium-mass nuclei: IV. Angular momentum projection and rotation-vibration coupling

Affiliations

Mechanisms of mirror energy difference for states exhibiting Thomas-Ehrman shift: Gamow shell model case studies of $^{18}$ Ne/ $^{18}$ O and $^{19}$ Na/ $^{19}$ O