Nuclear Theory·nucl-th

Thursday·June 6, 2019

7 papers—3 primary·4 cross-listed

01
[Submitted on 4 Jun 2019]
Neutron matter at the interface(s): static response and effective mass
Mateusz Buraczynski🇨🇦 · Nawar Ismail🇨🇦 · Alexandros Gezerlis🇨🇦
Neutron matter is interesting both as an extension of terrestrial nuclear physics and due to its significance for the study of neutron stars. In this work, after some introductory comments on nuclear forces, nuclear ab initio theory, and nuclear phenomenology, we employ two techniques, Quantum Monte Carlo (QMC) and Energy Density Functionals, to practically handle an extended system composed of strongly interacting neutrons. We start by summarizing work on the static response of neutron matter, which considers the impact of external influences on the time-independent system. We then proceed to discuss new results of the energy of quasiparticle excitations in neutron matter, including QMC calculations with chiral or phenomenological nucleon-nucleon interactions. As part of this study, we carefully study the approach of our finite-number computations toward the infinite-system limit.
Comments:
12 pages, 8 figures; v2 corresponds to published version
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas)
arXiv:
1906.01674 [pdf]
EPJA(2020)·8 citations
02
[Submitted on 5 Jun 2019]
Superfluid Phase Transitions and Effects of Thermal Pairing Fluctuations in Asymmetric Nuclear Matter
Hiroyuki Tajima · Tetsuo Hatsuda · Pieter van Wyk · Yoji Ohashi
We investigate superfluid phase transitions of asymmetric nuclear matter at finite temperature ( $T$ ) and density ( $ρ$ ) with a low proton fraction ( $Y_{p} \leq 0.2$ ) which is relevant to the inner crust and outer core of neutron stars. A strong-coupling theory developed for two-component atomic Fermi gases is generalized to the four-component case and is applied to the system of spin- $1/2$ neutrons and protons. The empirical phase shifts of neutron-neutron (nn), proton-proton (pp) and neutron-proton (np) interactions up to $k = 2$ $fm^{- 1}$ are described by multi-rank separable potentials. We show that (i) the critical temperature of the neutron superfluidity $T_{c}^{nn}$ at $Y_{p} = 0$ agrees well with Monte Carlo data at low densities and takes a maximum value $T_{c}^{nn} = 1.68$ MeV at $ρ / ρ_{0} = 0.14$ with $ρ_{0} = 0.17$ fm $^{- 3}$ , (ii) the critical temperature of the proton superconductivity $T_{c}^{pp}$ for $Y_{p} \leq 0.2$ is substantially suppressed at low densities due to np-pairing fluctuations and starts to dominate over $T_{c}^{nn}$ only above $ρ / ρ_{0} = 0.70$ $(0.77)$ for $Y_{p} = 0.1$ $(0.2)$ , and (iii) the deuteron condensation temperature $T_{c}^{d}$ is suppressed at $Y_{p} \leq 0.2$ due to the large mismatch of the two Fermi surfaces.
Comments:
23 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con)
arXiv:
1906.02098 [pdf]
Sci.Rep.(2019)·21 citations
03
[Submitted on 5 Jun 2019]
Renormalizing random-phase approximation by using exact pairing
L. Tan Phuc · N. Quang Hung · N. Dinh Dang
A fully self-consistent renormalized random-phase approximation is constructed based on the self-consistent Hartree-Fock mean field plus exact pairing solutions (EP). This approach exactly conserves the particle number and restores the energy-weighted sum rule, which is violated in the conventional renormalized particle-hole random-phase approximation for a given multipolarity. The numerical calculations are carried out for several light, medium, and heavy-mass nuclei such as $^{22}$ O, $^{60}$ Ni, and $^{90}$ Zr by using an effective MSk3 interaction. To study the pygmy dipole resonance (PDR), the calculations are also performed for the two light and neutron-rich $^{24, 28}$ O isotopes, whose PDRs are known to be dominant. The results obtained show that the inclusion of ground-state correlations beyond the random-phase approximation (RPA) by means of the occupation numbers obtained from the EP affects the RPA solutions within the whole mass range, although this effect decreases with increasing the mass number. At the same time, the anti-pairing effect is observed via a significant reduction of pairing in neutron-rich nuclei. The enhancement of PDR is found in most of neutron-rich nuclei under consideration within our method.
Comments:
26 pages and 10 figures. Accepted in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1906.02137 [pdf]
PRC(2019)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Neutron matter at the interface(s): static response and effective mass

Superfluid Phase Transitions and Effects of Thermal Pairing Fluctuations in Asymmetric Nuclear Matter

Renormalizing random-phase approximation by using exact pairing

Affiliations