Nuclear Theory·nucl-th

Wednesday·April 6, 2022

18 papers—9 primary·9 cross-listed

01
Pseudo-gauges and relativistic spin hydrodynamics for interacting Dirac and Proca fields
Nora Weickgenannt🇩🇪 · David Wagner🇩🇪 · Enrico Speranza🇺🇸
We present the explicit expressions of different pseudo-gauge transformations for Dirac and Proca fields considering a general interaction term. The particular case of the interaction of Dirac and Proca fields with a background electromagnetic field is also studied. Starting from the quantum kinetic theory with collisions derived from the Wigner-function formalism for massive spin-1/2 and spin-1 particles, we establish a connection between different pseudo-gauges and relativistic spin hydrodynamics. The physical implications of the various decompositions of orbital and spin angular momentum are discussed.
nucl-thPRD(2022)·54 citations
02
Calculations of $p (n, γ) d$ reaction in chiral effective field theory
Weijie Du🇺🇸 · Soham Pal🇺🇸 · Mamoon Sharaf🇺🇸 · Peng Yin🇺🇸 · Shiplu Sarker🇺🇸 · Andrey M. Shirokov🇷🇺 · James P. Vary🇺🇸
We present a calculation of the radiative capture cross section $p (n, γ) d$ in the low-energy range, where the $M 1$ reaction channel dominates. Employing the LENPIC nucleon-nucleon interaction up to the fifth order (N4LO) that is regularized by the semi-local coordinate space regulators, we obtain the initial and final state wave functions, and evaluate the phase shifts of the scattering state and deuteron properties. We derive the transition operator from the chiral effective field theory up to the next-to-next-to leading order (N2LO), where we also regularize the transition operator using regulators consistent with those of the interactions. We compute the capture cross sections and the results show a converging pattern with the chiral-order expansion of the nucleon-nucleon interaction, where the regulator dependence of the results is weak when higher-order nucleon-nucleon interactions are employed. We quantify the uncertainties of the cross-section results due to the chiral-order truncation. The chirally complete and consistent cross-section results are performed up to N2LO and they compare well with the experiments and other theoretical predictions.
nucl-thastro-ph.SRhep-phPRC(2022)·12 citations
03
Applications of the dynamical generator coordinate method to quadrupole excitations
N. Hizawa · K. Hagino · K. Yoshida
We apply the dynamical generator coordinate method (DGCM) with a conjugate momentum to a nuclear collective excitation. To this end, we first discuss how to construct a numerically workable scheme of the DGCM for a general one-body operator. We then apply the DGCM to the quadrupole vibration of $^{16}$ O using the Gogny D1S interaction. We show that both the ground state energy and the excitation energies are lowered as compared to the conventional GCM with the same number of basis functions. We also compute the sum rule values for the quadrupole and monopole operators, and show that the DGCM yields more consistent results than the conventional GCM to the values from the double commutator. These results imply that the conjugate momentum is an important and relevant degree of freedom in collective motions.
nucl-thcond-mat.str-elPRC(2022)·12 citations
04
Octupole correlations in collective excitations of neutron-rich $N \approx 56$ nuclei
Kosuke Nomura
Octupole correlations in the low-energy collective states of neutron-rich nuclei with the neutron number $N \approx 56$ are studied within the interacting boson model (IBM) that is based on the nuclear density functional theory. The constrained self-consistent mean-field (SCMF) calculations using a universal energy density functional and a pairing interaction provide the potential energy surfaces in terms of the axially-symmetric quadrupole and octupole deformations for the even-even nuclei $^{86 - 94}$ Se, $^{88 - 96}$ Kr, $^{90 - 98}$ Sr, $^{92 - 100}$ Zr, and $^{94 - 102}$ Mo. The SCMF energy surface is then mapped onto the energy expectation value of a version of the IBM in the boson condensate state, which consists of the neutron and proton monopole $s$ , quadrupole $d$ , and octupole $f$ bosons. This procedure determines the strength parameters of the IBM Hamiltonian, which is used to compute relevant spectroscopic properties. At the SCMF level, no octupole deformed ground state is obtained, while the energy surface is generally soft in the octupole deformation at $N \approx 56$ . The predicted negative-parity yrast bands with the bandhead state $3_{1}^{-}$ weakly depend on $N$ and become lowest in energy at $N = 56$ in each of the considered isotopic chains. The model further predicts finite electric octupole transition rates between the lowest negative- and the positive-parity ground-state bands.
nucl-thnucl-exPRC(2022)·16 citations
05
Effect of nucleon effective mass and symmetry energy on the neutrino mean free path in a neutron star
Parada T. P. Hutauruk🇰🇷 · Hana Gil🇰🇷 · Seung-il Nam🇰🇷 · Chang Ho Hyun🇰🇷
The Korea-IBS-Daegu-SKKU energy density functional (KIDS-EDF) models, constructed from the perturbative expansion of the energy density in nuclear matter, have been successfully and widely applied in describing the properties of finite nuclei and infinite nuclear matter. In the present work, we extend the applications of the KIDS-EDF models to investigate the implications of the nucleon effective mass and nuclear symmetry energy for the properties of neutron stars (NSs) and neutrino interaction with the NS constituent matter in the linear response approximation (LRA). At fixed neutrino energy and momentum transfer, we analyze the total differential cross section of neutrino, the neutrino mean free path (NMFP), and the NS mass-radius (M-R) relations. Remarkable results are given by the KIDS0-m*87 and SLy4 models, in which $M_{n}^{*} / M ≲ 1$ , and their NMFPs are quite higher in comparison with those obtained from the KIDS0, KIDS-A, and KIDS-B models, which result in $M_{n}^{*} / M ≳ 1$ . For the KIDS0, KIDS-A, and KIDS-B models, we obtain $λ ≲ R_{NS}$ , indicating that these models could predict the slow NS cooling and neutrino trapping in NSs. In contrast, the KIDS0-m*87 and SLy4 models yield $λ ≳ R_{NS}$ and thus we expect faster NS cooling and a small possibility of neutrino trapping within NSs. We also calculate the NMFP as a function of the neutrino energy and the nuclear matter density and find that the NMFP decreases as the density and neutrino energy increase, which is consistent with the result obtained in the Brussels-Montreal Skyrme (BSk17 and BSk18) models at saturation density.
nucl-thastro-ph.HEhep-phPRC(2022)·17 citations
06
Heavy baryons in hot stellar matter with light nuclei and hypernuclei
Tiago Custódio🇵🇹 · Helena Pais🇵🇹 · Constança Providência🇵🇹
The production of light nuclei and hypernuclei together with heavy baryons, both hyperons and $Δ$ -baryons, in low density matter as found in stellar environments such as supernova or binary mergers is studied within relativistic mean-field models. Five light nuclei were considered together with three light hypernuclei. The presence of both hyperons and $Δ$ -baryons shift the dissolution of clusters to larger densities and increase the abundance of clusters. This effect is larger the smaller the charge fraction and the higher the temperature. The couplings of the $Δ$ -baryons were chosen imposing that the nucleon effective mass remains finite inside neutron stars.
nucl-thastro-ph.HEPRC(2022)·2 citations
07
Constraints from $Λ$ hypernuclei on the $Λ N N$ content of the $Λ$ -nucleus potential
E. Friedman🇮🇱 · A. Gal🇮🇱
A depth of $D_{Λ} \approx - 28$ MeV for the $Λ$ -nucleus potential was confirmed in 1988 by studying $Λ$ binding energies deduced from $(π^{+}, K^{+})$ spectra measured across the periodic table. Modern two-body hyperon-nucleon interaction models require additional interaction terms, most likely $Λ N N$ three-body terms, to reproduce $D_{Λ}$ . In this work we apply a suitably constructed $Λ$ -nucleus density dependent optical potential to binding energy calculations of observed $1 s_{Λ}$ and $1 p_{Λ}$ states in the mass range $12 \leq A \leq 208$ . The resulting $Λ N N$ contribution to $D_{Λ}$ , about 14 MeV repulsion at symmetric nuclear matter density $ρ_{0} = 0.17$ fm $^{- 3}$ , makes $D_{Λ}$ increasingly repulsive at $ρ ≳ 3 ρ_{0}$ , leading possibly to little or no $Λ$ hyperon content of neutron-star matter. This suggests in some models a stiff equation of state that may support two solar-mass neutron stars.
nucl-thhep-phnucl-exPLB(2023)·38 citations
08
Splitting of elliptic flow in a tilted fireball
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳
The splitting of elliptic flow measured in different regions of the momentum space of produced hadrons has been recently studied in transport models and proposed as a sensitive probe of the angular momentum carried by the fireball produced in a relativistic heavy ion collision. The initial state angular momentum also gives rise to rapidity odd directed flow which has been measured. We consider a relativistic hydrodynamic framework with the initial matter distribution suitably calibrated to describe the observed directed flow and apply it to study the spilt in the elliptic flow. Our study suggests that the split in the elliptic flow is mostly driven by directed and triangular flows and may be used to constrain models of initial state rapidity distribution of matter in the fireball.
nucl-thhep-exhep-phnucl-exPRC(2022)·11 citations
09
Probing the nuclear deformation with three-particle asymmetric cumulant in RHIC isobar runs
Shujun Zhao🇨🇳 · Hao-jie Xu🇨🇳 · Yu-Xin Liu🇨🇳 · Huichao Song🇨🇳
$_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr collisions at $s_{_{NN}} = 200$ GeV provide unique opportunities to study the geometry and fluctuations raised from the deformation of the colliding nuclei. Using iEBE-VISHNU hybrid model, we predict $ac_{2} {3}$ ratios between these two collision systems and demonstrate that the ratios of $ac_{2} {3}$ , as well as the ratios of the involving flow harmonics and event-plane correlations, are sensitive to quadrupole and octupole deformations, which could provide strong constrains on the shape differences between $^{96}$ Ru and $^{96}$ Zr. We also study the nonlinear response coefficients $χ_{4, 22}$ , which show insensitivity to the deformation effect.
nucl-thnucl-exPLB(2023)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE