Nuclear Theory·nucl-th

Wednesday·October 2, 2024

19 papers—7 primary·12 cross-listed

01
Low-energy enhancement of the magnetic dipole radiation in odd-mass lanthanides
D. DeMartini🇺🇸 · Y. Alhassid🇺🇸
We compute the magnetic dipole (M1) $γ$ -ray strength functions ( $γ$ SF) for the odd-mass lanthanides $^{143 - 151}$ Nd and $^{147 - 153}$ Sm using the shell-model Monte Carlo method in combination with the static-path approximation and the maximum-entropy method. In particular, we quantify the statistical uncertainties in the calculated M1 $γ$ SFs and show that they are under control for the excitation energies relevant to the experiments despite a Monte Carlo sign problem that originates in the projection onto an odd number of neutrons. We identify a low-energy enhancement (LEE) in the M1 $γ$ SFs of these odd-mass lanthanides, which was recently observed experimentally in some of them. We also find a scissors mode resonance (SR) in the strongly deformed isotopes. We observe that the decrease in the LEE strength with neutron number along an isotopic chain is compensated for by an increase in the SR strength in the deformed nuclei. We compare our results with recent experiments.
nucl-thPRC(2025)·4 citations
02
Inferring three-nucleon couplings from multi-messenger neutron-star observations
Rahul Somasundaram🇺🇸 · Isak Svensson🇩🇪 · Soumi De🇺🇸 · Andrew E. Deneris🇺🇸 · Yannick Dietz🇩🇪 · Philippe Landry🇨🇦 · Achim Schwenk🇩🇪 · Ingo Tews🇺🇸
Understanding the interactions between nucleons in dense matter is an important challenge in theoretical physics. Effective field theories have emerged as the dominant approach to address this problem at low energies, with many successful applications to the structure of nuclei and the properties of dense nucleonic matter. However, how far into the interior of neutron stars these interactions can describe dense matter is an open question. Here, we develop a framework that enables the inference of three-nucleon couplings in dense matter directly from astrophysical neutron star observations. We apply this formalism to the LIGO/Virgo gravitational-wave event GW170817 and the X-ray measurements from NASA's Neutron Star Interior Composition Explorer and establish direct constraints for the couplings that govern three-nucleon interactions in chiral effective field theory. Furthermore, we demonstrate how next-generation observations of a population of neutron star mergers can offer stringent constraints on three-nucleon couplings, potentially at a level comparable to those from laboratory data. Our work directly connects the microscopic couplings in quantum field theories to macroscopic observations of neutron stars, providing a way to test the consistency between low-energy couplings inferred from terrestrial and astrophysical data.
nucl-thNature Commun.(2025)·24 citations
03
Magnetic Field Effects on Hadron Yields and Fluctuations
Volodymyr Vovchenko🇺🇸
We explore the impact of an external magnetic field on hadron yields and fluctuations in a thermalized system within the hadron resonance gas (HRG) model using an expanded Thermal-FIST package. The magnetic field sizably enhances the final proton-to-pion (p/ $π$ ) ratio due to $Δ (1232)^{++}$ decay feeddown indicating that this ratio may serve as a potential magnetometer for freeze-out conditions. At the same time, magnetic field does not generate additional dynamical fluctuations of hadron numbers. This suggests that fluctuations in heavy-ion collisions provide limited additional information about the magnetic field beyond what is already inferred from mean multiplicities.
nucl-thhep-phEPJ Web Conf.(2025)·0 citations
04
Vector interaction bounds in NJL-like models from LQCD estimated curvature of the chiral crossover line
Mahammad Sabir Ali🇮🇳 · Deeptak Biswas🇮🇳 · Chowdhury Aminul Islam🇩🇪
We obtain improved bounds on both the flavor-independent and -dependent vector interactions in a $2 + 1$ -flavor Nambu\textendash Jona-Lasinio (NJL) model using the latest precise LQCD results of the curvature coefficients of the chiral crossover line. We find that these lattice estimated curvature coefficients allow for both attractive and repulsive types of interactions in both the cases. With this constrained ranges of vector interactions, we further predict the behavior of the second $(κ_{2}^{B})$ and fourth $(κ_{4}^{B})$ order curvature coefficients as a function of the strangeness chemical potential $(μ_{S})$ . We observe that the flavor mixing effects, arising from the flavor-independent vector interaction as well as from the 't Hooft interaction, play an important role in $k_{2}^{B}$ . We propose that the mixing effects due to the vector interaction can be separated from those arising from the 't Hooft interaction by analyzing the behavior of $k_{2}^{B}$ as a function of $μ_{S}$ . Finally, we locate the critical endpoint in the $T - μ_{B}$ plane using the model-estimated ranges of vector interactions and find the model's predictions to be consistent with the latest LQCD bounds.
nucl-thhep-lathep-phEPJA(2025)·6 citations
05
The comparison of the state-of-the-art nucleon-nucleon potentials from phase shift to nuclear matter
Ke Nan🇨🇳 · Jinniu Hu🇨🇳 · Hong Shen🇨🇳 · Ying Zhang🇨🇳
The nucleon-nucleon ( $N N$ ) potential is the residual interaction of the strong interaction in the low-energy region and is also the fundamental input to the study of atomic nuclei. Based on the non-perturbative properties of the quantum chromodynamics (QCD), $N N$ potential is not yet directly accessible from QCD theory. Therefore, various models of $N N$ interactions have been constructed based on Yukawa's meson exchange pictures since the 1930s, including one-boson-exchange models, coordinate operator models and chiral effective field models. Analysis of extensive $N N$ scattering data has shown that the two-body nuclear force exhibits a short-range repulsion and intermediate-range attraction, and decays rapidly with increasing distance. A series of charge-dependent high-precision $N N$ interactions have been further developed in the past thirty years, such as the AV18 potential, CD-Bonn potential, pvCD-Bonn potentials, and the chiral effective nuclear potentials with momentum expansion up to the fifth order. In this work, the phase shifts at different channels, the cross sections, the entanglement entropy in spin space, and the equations of state of symmetric nuclear matter and pure neutron matter from these high-precision $N N$ interactions are calculated and systematically compared. It can be found that they have significant differences in the cases with high angular momentum, high laboratory energy, and high-density regions.
nucl-thIJMPE(2024)·3 citations
06
Mirror and triplet energy differences in $s d$ -shell nuclei using microscopic interactions with isospin-symmetry breaking effects
Chandan Sarma · Praveen C. Srivastava · Toshio Suzuki · Noritaka Shimizu
In this study, we developed and tested two different isospin symmetry-breaking (ISB) versions of the microscopic DJ16A interaction. Starting with the isospin symmetric DJ16A interaction, we introduced two different Coulomb interactions- Coulomb-CD and Coulomb-w/SRC- along with phenomenological charge symmetry breaking (CSB) and charge independence breaking (CIB) effects. Then, we employed these interactions to calculate $b$ - and $c$ -parameters of the isobaric multiplet mass equation for $∣ T_{z} ∣ = 1/2$ and $∣ T_{z} ∣ = 1$ nuclei across the $s d$ -shell. Our results indicate that the DJ16A $^{†}$ interaction provides the most accurate $b$ -parameter predictions between the two DJ16A-based interactions. Additionally, we explored mirror energy differences (MEDs) in low-energy spectra around $A = 20$ and demonstrated that large MEDs are primarily associated with high occupancies of the $1 s_{1/2}$ orbital. Furthermore, $E 2$ transition strengths were calculated using both DJ16A-based ISB interactions agreed with the experimental data, with minimal ISB effects observed on these transitions. Overall, the DJ16A $^{†}$ interaction serves as a complementary set to the newly developed USD-family interactions, USDC, and USDCm and can be further tested for other mirror nuclei across the $s d$ -shell to study nuclear structure properties and ISB effects in nuclear $β$ -decay.
nucl-thnucl-ex3 citations
07
Ab initio computations of atomic nuclei
T. Papenbrock🇺🇸
Ab initio computations of atomic nuclei, based on Hamiltonians from effective field theories of quantum chromodynamics, are now routinely used to predict and describe properties of medium heavy nuclei, and even the heavy nucleus $^{208}$ Pb has been reached. These lecture notes describe what are the central ideas and concepts behind the Hamiltonians and some of the methods that have enabled this progress.
nucl-th11 citations

Affiliations

first authorsco-authorsvia INSPIRE

Low-energy enhancement of the magnetic dipole radiation in odd-mass lanthanides

Inferring three-nucleon couplings from multi-messenger neutron-star observations

Magnetic Field Effects on Hadron Yields and Fluctuations

Vector interaction bounds in NJL-like models from LQCD estimated curvature of the chiral crossover line

The comparison of the state-of-the-art nucleon-nucleon potentials from phase shift to nuclear matter

Mirror and triplet energy differences in sd-shell nuclei using microscopic interactions with isospin-symmetry breaking effects

Ab initio computations of atomic nuclei

Affiliations

Mirror and triplet energy differences in $s d$ -shell nuclei using microscopic interactions with isospin-symmetry breaking effects