Nuclear Theory·nucl-th

Monday·April 27, 2020

10 papers—8 primary·2 cross-listed

01
Longitudinal dependence of B and D meson nuclear modifications in heavy-ion collisions at RHIC and the LHC
Caio A. G. Prado🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇺🇸 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳
It is widely acknowledged that heavy flavor probes are sensitive to the properties of the quark-gluon plasma and are often considered an important tool for the plasma tomography studies. Forward rapidity observables can provide further insight on the dynamics of the medium due to the interplay between the medium size and the differences in the production spectra of heavy quark probes. In this proceedings we present the nuclear modification factor $R_{AA}$ 's for B and D mesons, as well as heavy flavor leptons, in the rapidity range $- 4.0 < y < 4.0$ obtained from relativistic Langevin equation with gluon radiation coupled with a (3+1)-dimensional viscous hydrodynamics medium background. We present comparison with experimental data at mid-rapidity as well as predictions for different rapidity ranges.
nucl-thhep-phnucl-exNPA(2021)·1 citation
02
Slope parameter of the symmetry energy and the structure of three-particle interactions in nuclear matter
Wolfgang Bentz · Ian C. Cloët
In the first part of this paper, we present a study of the symmetry energy ( $a_{s}$ ) and its slope parameter ( $L$ ) for nuclear matter in the framework of the Fermi liquid theory of Landau and Migdal. We derive an exact relation between $a_{s}$ and $L$ , which involves the nucleon effective masses and three-particle Landau-Migdal parameters. We present simple estimates which suggest that there are two main mechanisms to explain the empirical values of $L$ : The proton-neutron effective mass difference in isospin asymmetric matter and the $ℓ = 0$ moment of the isovector in-medium three-particle scattering amplitude. In the second part of this paper, we discuss the general structure of three-particle interactions in nuclear matter in the framework of the Fermi liquid theory. The connections to the Bethe-Brueckner-Goldstone theory and other approaches are also discussed. We show explicitly how the first few terms in the Faddeev series, together with medium induced three-particle interactions, emerge naturally in the Fermi liquid theory.
nucl-thPRC(2022)·5 citations
03
Study of single-particle resonant states with Green's function method
Cheng Chen · Zhi Pan Li · Yu Xiao Li · Ting-Ting Sun
The relativistic mean field theory with the Green's function method is taken to study the single-particle resonant states. Different from our previous work [Phys.Rev.C 90,054321(2014)], the resonant states are identified by searching for the poles of Green's function or the extremes of the density of states. This new approach is very effective for all kinds of resonant states, no matter it is broad or narrow. The dependence on the space size for the resonant energies, widths, and the density distributions in the coordinate space has been checked and it is found very stable. Taking $^{120}$ Sn as an example, four new broad resonant states $2 g_{7/2}$ , $2 g_{9/2}$ , $2 h_{11/2}$ and $1 j_{13/2}$ are observed, and also the accuracy for the width of the very narrow resonant state $1 h_{9/2}$ is highly improved to be $1 \times 1 0^{- 8}$ MeV. Besides, our results are very close to those by the complex momentum representation method and the complex scaling method.
nucl-thCPC(2020)·12 citations
04
First-principles modelling of the magnetic structure of the lightest nuclear systems using effective field theory without pions
Hilla De-Leon🇮🇱 · Doron Gazit🇮🇱
The strong interaction, i.e., quantum chromodynamics at the low energy nuclear regime, is notoriously known to be challenging for predictive modeling. Here, we use the simplest possible nuclear effective field theory (EFT), and show that in the case of the magnetic structure of nuclear systems with $A = 2$ and $A = 3$ nucleons, it is highly precise as well as predictive. The theoretical framework is the pionless EFT (\pilesseft), of point nucleons with contact interactions, expanded consistently up to next-to-leading order (NLO) in perturbation theory, i.e., including only eleven low-energy parameters, and augmented by a novel Bayesian analysis of theoretical uncertainties. The theory accurately predicts the shell structure reflected in the values of the magnetic moments and reactions of these nuclei within $\approx 1%$ calculated theoretical uncertainty. We show that this perfect prediction originates in implicit a-posteriori properties of the calculation, particularly an unexpectedly small expansion parameter, as well as a vanishing contribution from the two-body isoscalar current.
nucl-th4 citations
05
Toward a bridge between relativistic and nonrelativistic density functional theories for nuclei
Z. X. Ren · P. W. Zhao
The nonrelativistic reduction of the self-consistent covariant density functional theory is realized for the first time with the similarity renormalization group (SRG) method. The reduced nonrelativistic Hamiltonian and densities are calculated by solving the corresponding flow equations with a novel expansion in terms of the inverse of the Dirac effective mass. The efficiency and accuracy of this newly proposed framework have been demonstrated for several typical spherical nuclei. It is found that the exact solutions of the total energies, traces of vector and scalar densities, and the root-mean-square radii are reproduced quite well for all nuclei. This allows one to directly compare and bridge the relativistic and nonrelativistic nuclear energy density functional theories in the future.
nucl-thquant-phPRC(2020)·29 citations
06
Application of microscopic transport model in the study of nuclear equation of state from heavy ion collisions at intermediate energies
Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳
The equation of state (EOS) of nuclear matter, i.e., the thermodynamic relationship between the binding energy per nucleon, temperature, density, as well as the isospin asymmetry, has been a hot topic in nuclear physics and astrophysics for a long time. The knowledge of the nuclear EOS is essential for studying the properties of nuclei, the structure of neutron stars, the dynamics of heavy ion collision (HIC), as well as neutron star mergers. HIC offers a unique way to create nuclear matter with high density and isospin asymmetry in terrestrial laboratory, but the formed dense nuclear matter exists only for a very short period, one cannot measure the nuclear EOS directly in experiments. Practically, transport models which often incorporate phenomenological potentials as an input are utilized to deduce the EOS from the comparison with the observables measured in laboratory. The ultrarelativistic quantum molecular dynamics (UrQMD) model has been widely employed for investigating HIC from the Fermi energy (40 MeV per nucleon) up to the CERN Large Hadron Collider energies (TeV). With further improvement in the nuclear mean-field potential term, the collision term, and the cluster recognition term of the UrQMD model, the newly measured collective flow and nuclear stopping data of light charged particles by the FOPI Collaboration can be reproduced. In this article we highlight our recent results on the studies of the nuclear EOS and the nuclear symmetry energy with the UrQMD model. New opportunities and challenges in the extraction of the nuclear EOS from transport models and HIC experiments are discussed.
nucl-th0 citations
07
Beam energy dependence of cumulants of the net-baryon, net-charge and deuteron multiplicity distributions in Au+Au collisions at $s_{N N} = 3.0 - 5.0$ GeV
Yunxiao Ye🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Dinghui Lu🇨🇳 · Fuqiang Wang🇨🇳
Within the ultra-relativistic quantum molecular dynamics (UrQMD) model, in which the Lorentz-covariant treatment of nuclear mean-field potential is considered, the fluctuations of net-baryon, net-charge and deuterons multiplicity distributions in Au+Au head-on collisions at $s_{N N} = 3.0 - 5.0$ GeV are calculated. The results show that the nuclear mean-field potential can significantly enhance the magnitude of baryon number fluctuations in narrow rapidity windows, and this enhancement rapidly weakens with increasing beam energy. However, for proton and net-charge number fluctuations, the mean-field effects are less noticeable than that for baryon number. In addition, for net-charge number fluctuations, the negative binomial distribution agrees well with the calculated results at mid-pseudorapidity window. Finally, the event-by-event fluctuations of deuteron number in the coalescence production picture are calculated as well, it is found that its cumulant ratios decrease linearly with increasing the average multiplicity of deuterons per event, i.e., increase with increasing beam energy.
nucl-thhep-phnucl-exPRC(2020)·10 citations
08
Shell model study of high-spin states and band terminations in $^{67}$ As
Vikas Kumar · Praveen C. Srivastava
In the present work, recently available experimental data for different bands of $^{67}$ As [Phys. Rev. C {\bf 98}, 024313 (2018)] have been interpreted within the framework of the shell model in full $f_{5/2} p g_{9/2}$ model space using JUN45 and jj44b effective interactions. The variation of $E$ - $E_{r o t}$ energy versus spin for different bands is shown to obtain useful information about band termination. We have also reported the electromagnetic transition probabilities, quadrupole and magnetic moments of $^{67}$ As. Except for some tentative high-spin states, the results are in good agreement with the available experimental data.The states $29/ 2^{+}$ - $45/ 2^{+}$ are described by three particles in $g_{9/2}$ , while $47/ 2^{+}$ and $51/ 2^{+}$ states are described by five particles in $g_{9/2}$ . The shell model results corresponding to nine tentative states such as $41/ 2_{1}^{+}$ and $45/ 2_{1}^{+}$ in band-1b; $41/ 2_{2}^{+}$ and $45/ 2_{2}^{+}$ in band-1a; $43/ 2_{2}^{+}$ , $47/ 2_{2}^{+}$ and $51/ 2_{1}^{+}$ in band-2a; $43/ 2_{1}^{+}$ and $47/ 2_{1}^{+}$ in band-2b are reported and discussed.
nucl-thNPA(2020)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE