Nuclear Theory·nucl-th

Tuesday·January 7, 2025

16 papers—12 primary·4 cross-listed

01
Nuclear EoS with finite range interaction and the Constrained Dynamics
Massimo Papa
The effects of the many-body correlations with respect the MF description characterizing the Constrained Molecular Dynamics are discussed in the case of finite and zero range effective microscopic interactions. In particular, for the system $^{64} N i +^{48} C a$ fusion-fission cross-sections, IMF production and transversal flow have been evaluated in the framework of the CoMD model at different incident energies. The results obtained significantly depend on whether the effects of the above-mentioned correlations are taken into account in the corresponding EoS.
nucl-thNuovo Cim.C(2025)·0 citations
02
Study of medium-mass and heavy hypernuclei produced through spallation and fission reactions in inverse kinematics
J. L. Rodríguez-Sánchez🇪🇸 · J. Cugnon🇧🇪 · J.-C. David🇫🇷 · J. Hirtz🇫🇷 · A. Kelić-Heil🇩🇪
Innovative experiments using the inverse kinematics technique to accelerate light, medium-mass, and heavy nuclei at relativistic energies have become excellent tools to produce and study hypernuclei. In this work, we investigate hypernuclei created in spallation reactions, where multifragmentation, particle evaporation, and fission processes play an important role in the formation of final hypernuclei residues. For the description of spallation reactions, we couple the Liège intranuclear cascade model, extended recently to the strange sector, to a new version of the ablation (ABLA) model that accounts for the evaporation of {\Lambda}-particles from hot hyperremnants produced during the intranuclear cascade stage. These state-of-the art models are then used to study the production of hypernuclei close to the drip lines through spallation-evaporation and fission reactions. Moreover, recent results obtained for the study of hypernuclei dynamics, in particular, for the constraint of the viscosity parameter involved in hyperfission reactions are also presented.
nucl-th0 citations
03
Parity-doubled nucleons can rapidly cool neutron stars
Liam Brodie🇺🇸 · Robert D. Pisarski🇺🇸
In confined hadronic matter, the spontaneous breaking and restoration of chiral symmetry can be described by considering nucleons, $N_{+} (939)$ , and excited states of opposite parity, $N_{-} (1535)$ . In a cold, dense hadronic phase where chiral symmetry remains spontaneously broken, direct Urca decay processes involving the $N_{-}$ are possible, e.g. $N_{-} \to N_{+} + e^{-} + ν ˉ_{e}$ . We show that at low temperature and moderate densities, because the $N_{-}$ is much heavier than the $N_{+}$ , such cooling dominates over standard $N_{+}$ direct Urca processes. This provides a strong astrophysical signature of the pattern of chiral symmetry restoration in neutron stars.
nucl-thastro-ph.HEhep-phPRL(2025)·4 citations
04
Atmospheric Antideuteron Flux Within a Dynamical Coalescence Approach
Jie Pu🇨🇳 · Xin Li🇨🇳 · Kai-Jia Sun🇨🇳 · Chun-Wang Ma🇨🇳 · Lie-Wen Chen🇨🇳
Cosmic antideuterons are considered as one of the most promising tools for the indirect detection of dark matter due to their ultra-low astrophysical backgrounds. Currently only upper limits on the antideuteron flux exist, but advancements in experimental detection technology may soon lead to positive signals. A major source of background is the production of secondary antideuterons through collisions of cosmic rays with the surrounding medium. In this study, antideuteron production is modeled using a multiphase transport model (AMPT) coupled with a dynamical coalescence model. By applying a widely used leaky box model and incorporating specific processes, we present a new theoretical baseline for atmospheric secondary antideuteron flux, including a tertiary contribution, from primary cosmic rays interacting with Earth's atmosphere. Our results indicate that the atmospheric antideuteron flux are within the range of various existing calculations and remain well below the upper limits set by the Balloon-borne Experiment with a Superconducting Spectrometer (BESS). The atmospheric antideuteron is found to dominate the antideuteron background at kinetic energies below $0.26$ GeV/n.
nucl-thhep-phJHEP(2025)·0 citations
05
Non-perturbative calculations of nuclear matter using in-medium similarity renormalization group
Xin Zhen🇨🇳 · Rongzhe Hu🇨🇳 · Haoyu Shang🇨🇳 · Jiawei Chen🇨🇳 · Junchen Pei🇨🇳 · Furong Xu🇨🇳
The non-perturbative {\it ab initio} calculations of infinite nuclear matter using In-Medium Similarity Renormalization Group (IMSRG) method is developed in this work, which enables calculations with chiral two and three-nucleon forces at N $^{2}$ LO and N $^{3}$ LO. Results from the many-body perturbation theory at different orders and coupled-cluster theory are also presented for comparison. It is shown that different many-body approaches lead to obvious discrepancies with a harder nuclear interaction for both pure neutron matter and symmetric nuclear matter. This work provides a novel alternative infrastructure for future studies of dense nuclear matter and strongly-correlated many-body systems.
nucl-thPLB(2025)·9 citations
06
Evolutions of in-medium baryon-baryon scattering cross sections and stiffness of dense nuclear matter from Bayesian analyses of FOPI proton flow excitation functions
Bao-An Li🇺🇸 · Wen-Jie Xie🇺🇸
Within a Bayesian statistical framework using a Gaussian Process (GP) emulator for an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model simulator of heavy-ion reactions with momentum-independent Skyrme interactions, we infer from the proton directed and elliptical flow in mid-central Au+Au reactions at beam energies from 150 to 1200 MeV/nucleon taken by the FOPI Collaboration the posterior Probability Distribution Functions (PDFs) of the in-medium baryon-baryon scattering cross section (BBSCS) modification factor $X$ (with respect to their free-space values) and the stiffness parameter $K$ of dense nuclear matter. We find that the most probable value of $X$ evolves from around 0.7 to 1.0 as the beam energy $E_{b e am} / A$ increases. On the other hand, the posterior PDF( $K$ ) may have dual peaks having roughly the same height or extended shoulders at high $K$ values. More quantitatively, the posterior PDF( $K$ ) changes from having a major peak around 220 MeV characterizing a soft EOS in the reaction at $E_{b e am} / A$ =150 MeV to one that peaks around 320 MeV indicating a stiff EOS in the reactions at $E_{b e am} / A$ higher than about 600 MeV. The transition from soft to stiff happens in mid-central Au+Au reactions at beam energies around 250 MeV/nucleon in which $K = 220$ MeV and $K = 320$ MeV are approximately equally probable. Altogether, the FOPI proton flow excitation function data indicate a gradual hardening of hot and dense nuclear matter as its density and temperature increase in reactions with higher beam energies.
nucl-thastro-ph.HEnucl-exPRC(2025)·11 citations
07
Diagrammatic Monte Carlo for Finite Systems at Zero Temperature
Stefano Brolli · Carlo Barbieri · Enrico Vigezzi
High-order virtual excitations play an important role in microscopic models of nuclear reactions at intermediate energies. However, the factorial growth of their complexity has prevented their consistent inclusion in ab initio many-body calculations. For infinite systems at finite temperature, such drawbacks can be overcome using diagrammatic Monte Carlo techniques to resum entire series of Feynman diagrams. We present a diagrammatic Monte Carlo algorithm that can be applied to self-bound systems with discrete energy levels at zero temperature, and demonstrate its potential for the Richardson model of nuclear pairing. We show that sampling the topological space of diagrams allows the inclusion of high-order excitations that are neglected in state-of-the-art approximations used in nuclear physics and quantum chemistry. We propose that sampling the diagrammatic space can overcome the long-standing gap between our microscopic understanding of structure and reactions in nuclear physics.
nucl-thPRL(2025)·12 citations
08
Axial-Vector and Tensor Spin Polarization and Chiral Restoration in Quark Matter
Tomoyuki Maruyama🇯🇵 · Toshitaka Tatsumi🇯🇵
We study spontaneous spin-polarizations of quark matter with flavour $S U (2)$ symmetry at zero temperature in the NJL model. In a relativistic framework, there are two types of the spin-spin interactions: axial-vector (AV) and tensor (T), which accordingly give rise to different types of spin-polarized materials. When the spin-spin interaction is sufficiently strong, the spin-polarized phase emerges within a specific density region. As the spin-spin interaction becomes stronger, this phase extends over higher density region beyond the critical density of chiral restoration in normal quark matter. We show that the spin-polarized phase leads to another kind of the spontaneous chiral symmetry breaking phase.
nucl-thhep-phSymmetry(2024)·0 citations
09
Nuclear Schiff Moments and CP Violation
Jonathan Engel🇺🇸
This paper reviews the calculation of nuclear Schiff moments, which one must know in order to interpret experiments that search for time-reversal-violating electric dipole moments in certain atoms and molecules. After briefly reviewing the connection between dipole moments and CP violation in and beyond the Standard Model of particle physics, Schiff's theorem, which concerns the screening of nuclear electric dipole moments by electrons, Schiff moments, and experiments to measure dipole moments in atoms and molecules, the paper examines attempts to compute Schiff moments in nuclei such as $^{199}$ Hg and octupole-deformed isotopes such as $^{225}$ Ra, which are particularly useful in experiments. It then turns to ab initio nuclear-structure theory, describing ways in which both the In-Medium Similarity Renormalization Group and coupled-cluster theory can be used to compute important Schiff moments more accurately than the less controlled methods that have been applied so far.
nucl-thAnn.Rev.Nucl.Part.Sci.(2025)·23 citations
10
Extracting the Speed of Sound in Heavy-Ion Collisions: A Study of Quantum-Initiated Fluctuations and Thermalization
Yu-Shan Mu🇨🇳 · Jing-An Sun🇨🇳 · Li Yan🇨🇳 · Xu-Guang Huang🇨🇳
The thermalization of quark-gluon plasma created in heavy-ion collisions is crucial for understanding its behavior as a relativistic fluid and the thermodynamic properties of the Quantum Chromodynamics (QCD). This study investigates the role of fluctuations in the relationship between transverse momentum and particle multiplicity, with a particular focus on their impact on extracting the QCD speed of sound. In a thermalized quark-gluon plasma, these fluctuations mostly originate from quantum fluctuations in the colliding nuclei, and exhibit a Gaussian distribution as a consequence of their independence from thermodynamic response. In contrast, non-thermalized systems display non-Gaussian fluctuations, reflecting the breakdown of thermalization. By leveraging the Gaussianity condition of quantum-initiated fluctuations, the physical value of the speed of sound can be extracted statistically, even in the presence of significant event-by-event fluctuations. This framework provides a robust diagnostic tool for probing thermalization and extracting thermodynamic properties in both large and small collision systems.
nucl-thhep-phnucl-exPRL(2025)·13 citations
11
Constraining the chiral magnetic effect using spectator and participant planes across Au+Au and isobar collisions at $s_{_{NN}} = 200$ GeV
Bang-Xiang Chen🇨🇳 · Xin-Li Zhao🇨🇳 · Guo-Liang Ma🇨🇳
We investigate the chiral magnetic effect (CME) in relativistic heavy-ion collisions through an improved two-plane method analysis of the $Δ γ$ observable, probing $C P$ -symmetry breaking in strong interactions and topological properties of the QCD vacuum. Using a multiphase transport model with tunable CME strengths, we systematically compare Au+Au and isobar collisions at $s_{_{NN}} = 200$ GeV. We observe a reduced difference in the CME signal-to-background ratio between the spectator and participant planes for Au+Au collisions compared to isobar collisions. A comprehensive chi-square analysis across all three collision systems reveals stronger CME signatures in Au+Au collisions relative to isobar collisions, particularly when measured with respect to the spectator plane. Our findings demonstrate an enhanced experimental reliability of the two-plane method for the CME detection in Au+Au collisions.
nucl-thhep-phnucl-exNucl.Sci.Tech.(2025)·1 citation
12
In-medium $Λ N$ interactions with leading order covariant chiral hyperon/nucleon-nucleon forces
Ru-You Zheng🇨🇳 · Zhi-Wei Liu🇨🇳 · Li-Sheng Geng🇨🇳 · Jin-Niu Hu🇨🇳 · Sibo Wang🇨🇳
In-medium $Λ N$ interactions are crucial in hypernuclei and neutron star physics. In this work, we study the in-medium $Λ N$ interaction within the relativistic Brueckner-Hartree-Fock (RBHF) framework, employing the leading-order covariant chiral hyperon/nucleon-nucleon forces for the first time. We demonstrate that a consistent description of both the experimental cross-section data and the `empirical value' of the $Λ$ single-particle potential can be achieved. This contrasts with the majority of studies in the non-relativistic framework, where higher-order two-body chiral forces are typically required. This study offers a new perspective on the in-medium $Λ N$ interactions, urgently needed in relativistic \textit{ab initio} hypernuclear physics studies.
nucl-thPLB(2025)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE