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Nuclear Theory·nucl-th

Tuesday·July 13, 2021

14 papers—7 primary·7 cross-listed

All14Primary7Cross-lists7
  1. 01

    Coulomb field correction due to virtual production in heavy ion collisions

    Thomas Settlemyre🇺🇸 · Aldo Bonasera🇨🇳 · Hua Zheng🇺🇸

    The correction to the Coulomb energy due to virtual production of pairs, which is on the order of one percent of the Coulomb energy at nuclear scales is discussed. The effects of including a pair-production term in the semi-empirical mass formula and the correction to the Coulomb barrier for a handful of nuclear collisions using the Bass and Coulomb potentials are studied. With an eye toward future work using Constrained Molecular Dynamics (CoMD) model, we also calculate the correction to the Coulomb energy and force between protons after folding with a Gaussian spatial distribution.

    nucl-thnucl-exNPA(2021)·4 citations
  2. 02

    Test of the hyperon-nucleon interaction within leading order covariant chiral effective field theory

    Jing Song🇨🇳 · Zhi-Wei Liu🇨🇳 · Kai-Wen Li🇨🇳 · Li-Sheng Geng🇨🇳

    Motivated by the recent experimental measurements of differential cross sections of the elastic scattering in the momentum range of to MeV by the J-PARC E experiment, we extend our previous studies of hyperon-nucleon interactions to relatively higher energies up to MeV for both the coupled-channel , and single-channel reactions. We show that although the leading order covariant chiral effective field theory is only constrained by the low energy data, it can describe the high energy data reasonably well, in particular, the J-PARC E40 differential cross sections. The predicted cusp structure close to the threshold in the reaction agrees with the latest ALICE observation as well as with the results of the next-to-leading order heavy baryon chiral effective theory. On the other hand, the comparison with the latest CLAS data on the cross sections between 0.9 and 2.0 GeV clearly indicates the need of higher order chiral potentials for such high momenta. This is also the case for the latest J-PARC data on the differential cross sections. Nevertheless, even for these cases, the predictions are in qualitative agreement with the data, albeit with large uncertainties, implying that the predicted total and differential cross sections are of relevance for ongoing and planned experiments.

    nucl-thhep-exhep-lathep-ph+1PRC(2022)·32 citations
  3. 03

    Evolution of nuclear charge radii in copper and indium isotopes

    Rong An · Xiang Jiang · Li-Gang Cao · Feng-Shou Zhang

    Systematic trends in nuclear charge radii are of great interest due to universal shell effects and odd-even staggering (OES). The modified root mean square (rms) charge radius formula, which phenomenologically accounts for the formation of neutron-proton () correlations, is here applied for the first time to the study of odd- copper and indium isotopes. Theoretical results obtained by the relativistic mean field (RMF) model with NL3, PK1 and NL3 parameter sets are compared with experimental data. Our results show that both OES and the abrupt changes across and shell closures are clearly reproduced in nuclear charge radii. The inverted parabolic-like behaviors of rms charge radii can also be described remarkably well between two neutron magic numbers, namely to for copper isotopes and to for indium isotopes. This implies that the -correlations play an indispensable role in quantitatively determining the fine structures of nuclear charge radii along odd- isotopic chains. Also, our conclusions have almost no dependence on the effective forces.

    nucl-thnucl-exCPC(2022)·10 citations
  4. 04

    Quark anomalous magnetic moment and its effects on the meson properties

    Zanbin Xing🇨🇳 · Khépani Raya🇨🇳 · Lei Chang🇨🇳

    A symmetry-preserving treatment of mesons, within a Dyson-Schwinger and Bethe-Salpeter equations approach, demands an interconnection between the kernels of the quark gap equation and meson Bethe-Salpeter equation. Appealing to those symmetries expressed by the vector and axial-vector Ward-Green-Takahashi identitiges (WGTI), we construct a two-body Bethe-Salpeter kernel and study its implications in the vector channel; particularly, we analyze the structure of the quark-photon vertex, which explicitly develops a vector meson pole in the timelike axis and the quark anomlaous magnetic moment term, as well as a variety of meson properties: mass and decay constants, electromagnetic form factors, and valence-quark distribution amplitudes.

    nucl-thhep-phPRD(2021)·21 citations
  5. 05

    Resonances of isospin triplet states within the \textit{ab initio} no-core Gamow shell model

    J. G. Li · N. Michel · W. Zuo · F. R. Xu

    The nuclei, i.e., H, He and Li, establish an interesting isospin isobaric system. H and Li are unbound broad resonances, whereas He is deeply bound in its ground state but unbound in all its excited states. The present situation is that experiments so far have not given consistent data on the resonances. Few-body calculations have well studied the scatterings of the systems. In the present work, we provide many-body calculations of the broad resonance structures, in an \textit{ab initio} framework with modern realistic interactions. It occurs that, indeed, H, Li and excited He are broad resonances, which is in accordance with experimental observations. The calculations also show that the first excited state almost degenerates with the ground state in the pair of mirror isobars of H and Li, which may suggest that the experimental data on energy and width are the mixture of the ground state and the first excited state. The isospin triplet formed with an excited state of He and ground states of H and Li is studied, focusing on the effect of isospin symmetry breaking.

    nucl-thnucl-exPRC(2021)·34 citations
  6. 06

    Non-conformal attractor in boost-invariant plasmas

    Chandrodoy Chattopadhyay🇺🇸 · Sunil Jaiswal🇮🇳 · Lipei Du🇺🇸 · Ulrich Heinz🇺🇸 · Subrata Pal🇮🇳

    We study the dissipative evolution of (0+1)-dimensionally expanding media with Bjorken symmetry using the Boltzmann equation for massive particles in relaxation-time approximation. Breaking conformal symmetry by a mass induces a non-zero bulk viscous pressure in the medium. It is shown that even a small mass (in units of the local temperature) drastically modifies the well-known attractor for the shear Reynolds number previously observed in massless systems. For generic nonzero particle mass, neither the shear nor the bulk viscous pressure relax quickly to a non-equilibrium attractor; they approach the hydrodynamic limit only late, at small values of the inverse Reynolds numbers. Only the longitudinal pressure, which is a combination of thermal, shear and bulk viscous pressures, continues to show early approach to a far-off-equilibrium attractor, driven by the rapid longitudinal expansion at early times. Second-order dissipative hydrodynamics based on a gradient expansion around locally isotropic thermal equilibrium fails to reproduce this attractor.

    nucl-thhep-phphysics.plasm-phPLB(2022)·62 citations
  7. 07

    A Detailed Examination of Astrophysical Constraints on the Symmetry Energy and the Neutron Skin of Pb with Minimal Modeling Assumptions

    Reed Essick · Philippe Landry · Achim Schwenk · Ingo Tews

    The symmetry energy and its density dependence are pivotal for many nuclear physics and astrophysics applications, as they determine properties ranging from the neutron-skin thickness of nuclei to the crust thickness and the radius of neutron stars. Recently, PREX-II reported a value of fm for the neutron-skin thickness of Pb, , implying a symmetry-energy slope parameter of MeV, larger than most ranges obtained from microscopic calculations and other nuclear experiments. We use a nonparametric equation of state representation based on Gaussian processes to constrain the symmetry energy , , and directly from observations of neutron stars with minimal modeling assumptions. The resulting astrophysical constraints from heavy pulsar masses, LIGO/Virgo, and NICER favor smaller values of the neutron skin and , as well as negative symmetry incompressibilities. Combining astrophysical data with chiral effective field theory (EFT) and PREX-II constraints yields MeV, MeV, and fm. We also examine the consistency of several individual EFT calculations with astrophysical observations and terrestrial experiments. We find that there is only mild tension between EFT, astrophysical data, and PREX-II's measurement (-value ) and that there is excellent agreement between EFT, astrophysical data, and other nuclear experiments.

    nucl-thastro-ph.HEnucl-exPRC(2021)·97 citations

Affiliations

first authorsco-authorsvia INSPIRE