Nuclear Theory·nucl-th

Friday·March 1, 2019

13 papers—6 primary·7 cross-listed

01
Electromagnetic Scattering in Degenerate and Partially Degenerate Nuclear Matter
Stephan Stetina🇦🇹
I calculate the rate of electromagnetic scattering in degenerate and partially degenerate plasmas composed of electrons, muons, protons, and neutrons. Correlations with strong interactions, induced by the polarizability of electromagnetically and strongly charged protons, are taken into account. At subnuclear densities induced interactions are shown to cause a drastic increase of the longitudinal scattering rate. The results obtained are particularly relevant for the electron contribution to transport in the outer core of neutron stars, and represent a first step towards a realistic calculation of transport phenomena in neutron star mergers.
nucl-thastro-ph.SRhep-ph1 citation
02
Dressed Quark Tensor Vertex and Nucleon Tensor Charge
Langtian Liu🇨🇳 · Lei Chang🇨🇳 · Yu-xin Liu🇨🇳
We construct the quark-antiquark scattering kernels of Bethe-Salpeter equation from the quark self-energy directly under two specific forms of quark-gluon vertices. The quark dressed tensor vertex is then calculated within this consistent framework and rainbow-ladder(RL) approximation. After employing a simplified nucleon model, the nucleon tensor charge can be defined with the tensor vertex. We then compute the tensor charge with the bare tensor vertex and the dressed vertices obtained in this framework and in RL approximation. The obtained results are consistent with the lattice QCD calculations. We also find that typically the gluon dressing effects suppress the nucleon tensor charge compared to the bare tensor vertex, by about $23%$ for RL approximation, and turn to be about $13%$ in this framework.
nucl-thhep-phPRD(2019)·11 citations
03
Reexamination of the $β^{+}$ decay process of $^{13} N$ nucleus
B.F. Irgaziev · Jameel-Un Nabi · Abdul Kabir
It is known from the scattering theory that the phase-shift of elastic collision does not provide a unique potential to describe the bound state of the two-particle system. The bound state wave function is the most crucial input for various nuclear processes bearing astrophysical significance. In this paper, we emphasize on the important role of the asymptotic normalization coefficients for description of the $^{13} N ⟶^{13} C + β^{+} + ν_{e}$ reaction. Using experimental data of the elastic scattering phase-shift of proton and neutron on $^{12} C$ , we find the asymptotic normalization coefficients which determine the tail of the bound state wave functions. This allows us to modify the wave functions of $^{13} N$ and $^{13} C$ within the single-particle approach using the inverse scattering theory. These wave functions are used to determine the nuclear matrix element for calculation of the half-life and log{\textit ft} values of $β^{+}$ decay of $^{13} N$ . The calculated values of the log{\textit ft} and half-life are smaller than the measured values when the single-particle wave functions are employed. Using overlap functions, instead of single-particle functions, we obtain a better comparison. The overlap function is represented as the product of single-particle function and the corresponding spectroscopic factor.
nucl-thastro-ph.SR0 citations
04
Low-energy dipole excitation modes in $^{10}$ Be
Yuki Shikata · Yoshiko Kanada-En'yo · Hiroyuki Morita
Low-energy dipole excitations in $^{10}$ Be were investigated based on the generator coordinate method with $α +^{6}$ He and $α + α + 2 n$ cluster models. We obtained three $1^{-}$ states in $E_{x} < 15$ ~MeV, which show different characters in the $E 1$ , compressive dipole, and toroidal dipole transition strengths. We found the strong toroidal dipole transition in the $1_{1}^{-}$ state, remarkable $E 1$ strength in the $1_{2}^{-}$ state, and the strong $E 1$ and compressive dipole strength in the $1_{3}^{-}$ state. The $1_{1}^{-}$ is described by the $α +^{6}$ He cluster structure, where as the $1_{2}^{-}$ and $1_{3}^{-}$ states are understood by three-body excitations of the $α + α + 2 n$ clustering.
nucl-thPTEP(2019)·8 citations
05
Energy-weighted sum rule for nuclear density functional theory
Nobuo Hinohara
The expressions for the energy-weighted sum rule of the isoscalar and isovector coordinate operators are derived based on the second-order fluctuation of the local densities. Conventional derivation of the Thouless theorem for the energy-weighted sum rule is based on the double commutator of the Hamiltonian, while the present derivation does not assume a Hamiltonian operator and is applicable to nuclear energy density functionals. The expressions include the contribution of the local gauge symmetry breaking of the energy density functional. It is shown that the local gauge invariance of the kinetic and current densities and kinetic pair density is important, while all the other local densities do not contribute to the energy-weighted sum rule of the coordinate operators. The finite-amplitude method calculations are performed and the expressions for the energy-weighted sum rule are numerically examined for the isoscalar and isovector multipole operators up to $L = 3$ for selected spherical and axially deformed nuclei.
nucl-thPRC(2019)·7 citations
06
Examination of Flow and Non-Flow Factorization Methods in Small Collision Systems
S.H. Lim🇺🇸 · Q. Hu🇺🇸 · R. Belmont🇺🇸 · K.K. Hill🇺🇸 · J.L. Nagle🇺🇸 · D.V. Perepelitsa🇺🇸
Two particle correlations have been used extensively to study hydrodynamic flow patterns in heavy-ion collisions. In small collision systems, such as $p$ $+$ $p$ and $p$ $+$ $A$ , where particle multiplicities are much smaller than in $A$ $+$ $A$ collisions, non-flow effects from jet correlations, momentum conservation, particle decays, etc. can be significant, even when imposing a large pseudorapidity gap between the particles. A number of techniques to subtract the non-flow contribution in two particle correlations have been developed by experiments at the Large Hadron Collider (LHC) and then used to measure particle flow in $p$ $+$ $p$ and $p$ $+$ Pb collisions. Recently, experiments at the Relativistic Heavy Ion Collider (RHIC) have explored the possibility of adopting these techniques for small collision systems at lower energies. In this paper, we test these techniques using Monte Carlo generators PYTHIA and HIJING, which do not include any collective flow, and AMPT, which does. We find that it is crucial to examine the results of such tests both for correlations integrated over particle transverse momentum $p_{T}$ and differentially as a function of $p_{T}$ . Our results indicate reasonable non-flow subtraction for $p$ $+$ $p$ collisions at the highest LHC energies, while failing if applied to $p$ $+$ $p$ collisions at RHIC. In the case of $p$ $+$ Au collisions at RHIC, both HIJING and AMPT results indicate a substantial over-subtraction of non-flow for $p_{T} ≳ 1 GeV / c$ and hence an underestimate of elliptic flow.
nucl-thnucl-exPRC(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Electromagnetic Scattering in Degenerate and Partially Degenerate Nuclear Matter

Dressed Quark Tensor Vertex and Nucleon Tensor Charge

Reexamination of the β+ decay process of 13N nucleus

Low-energy dipole excitation modes in 10Be

Energy-weighted sum rule for nuclear density functional theory

Examination of Flow and Non-Flow Factorization Methods in Small Collision Systems

Affiliations

Reexamination of the $β^{+}$ decay process of $^{13} N$ nucleus

Low-energy dipole excitation modes in $^{10}$ Be