Nuclear Theory·nucl-th

Monday·August 22, 2022

6 papers—4 primary·2 cross-listed

01
[Submitted on 18 Aug 2022]
Early quark deconfinement in compact star astrophysics and heavy-ion collisions
Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Tobias Fischer🇵🇱 · Andreas Bauswein🇩🇪
Based on a recently developed relativistic density functional approach to color-superconducting quark matter and a novel quark-hadron transition construction which phenomenologically accounts for the effects of inhomogeneous pasta phases and quark-hadron continuity, we construct a class of hybrid equations of state applicable at the regimes typical for compact star astrophysics and heavy ion collisions. We outline that early quark deconfinement is a notable consequence of strong diquark pairing providing a good agreement with the observational data and driving the trajectories of the matter evolution during the supernovae explosions toward the regimes typical for the compact star mergers and heavy-ion collisions.
Comments:
Presented at the $2 9^{th}$ Conference ''Quark Matter 2022'' on ultrarelativistic nucleus-nucleus collisions, April 4-10, 2022, Kraków, Poland; minor typo corrections in v2
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.09085 [pdf]
Acta Phys.Polon.Supp.(2023)·4 citations
02
[Submitted on 19 Aug 2022]
ZRH22: An improved analysis of the pion-nucleon measurements at low energy
Evangelos Matsinos
Carried out in this study is an improved analysis of the measurements of the three pion-nucleon ( $π N$ ) reactions, which can be subjected to experimental investigation at low energy (pion laboratory kinetic energy $T \leq 100$ MeV), i.e., of the two elastic-scattering (ES) processes $π^{\pm} p \to π^{\pm} p$ and of the $π^{-} p$ charge-exchange (CX) reaction $π^{-} p \to π^{0} n$ . After the application of the four steps of the first phase of the new analysis procedure, $52$ entries - of the $1150$ degrees of freedom of the new initial database (DB) of this project - were identified as outliers and were removed from the input. In this manner, three `clean' (devoid of outliers) DBs were obtained, which were submitted to further analysis using the ETH model. The phase-shift analysis (PSA) of the ES measurements comprises the results of one hundred joint fits to the data, each fit being carried out at one value (randomly generated, in normal distribution, according to a recent result) of the model parameter $m_{σ}$ , which is associated with the effective range of the scalar-isoscalar part of the $π N$ interaction. The result of the PSA of the ES data for the (square of the) charged-pion coupling constant $f_{c}$ is: $f_{c}^{2} = 0.0764 (15)$ . An exclusive fit of the ETH model to the low-energy $π^{-} p$ CX DB was also performed, for the first time in the recent years, after suppressing the contributions to the partial-wave amplitudes of the ETH model which originate from the scalar-isoscalar $t$ -channel Feynman diagram. The predictions, obtained from these two types of fits (PSA of the ES data and exclusive fit of the ETH model to the $π^{-} p$ CX DB) for the (popular) symmetrised relative difference $R_{2}$ were compared in the entire low-energy region, separately for the $s$ wave, as well as for the no-spin-flip and spin-flip $p$ -wave parts of the $π N$ scattering amplitude.
Comments:
98 pages, 24 figures, 16 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.09207 [pdf]
1 citation
03
[Submitted on 19 Aug 2022]
Dense Nuclear Matter with Baryon Overlap
Jesper Leong (1) · Theo F. Motta ((1) and (2)) · Anthony W. Thomas (1) · P. A. M. Guichon (3) ((1) CSSM and ARC Centre of Excellence for Dark Matter Particle Physics, Department of Physics, University of Adelaide, (2) Institut für Theoretische Physik, Justus-Liebig-Universität Giessen, (3) Irfu, CEA, Université Paris-Saclay)
The possibility of new short-distance physics applicable inside the cores of NS is incorporated into the equation of state generated by the quark-meson coupling model. The contribution of this new physics to the energy density is taken to be proportional to the amount of overlap between the quark cores of the baryons involved. With no change to the properties of symmetric nuclear matter at saturation density, including an incompressibility compatible with data on giant monopole resonances, one can sustain neutron stars with a maximum mass $M_{ma x} > 2.1$ M $_{⊙}$ , even when hyperons are included.
Comments:
16 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.09331 [pdf]
2 citations
04
[Submitted on 19 Aug 2022]
Continuum random-phase approximation for (n,\gamma) reactions on neutron-rich nuclei: collective effects and resonances
Teruyuki Saito · Masayuki Matsuo
We formulate a microscopic theory to calculate cross section of the radiative neutron capture reaction on neutron-rich nuclei using the continuum random-phase approximation (cRPA) to the time-dependent density functional theory (TDDFT). With an intension of applying to the r-process, for which the statistical reaction model may not be appropriate, we describe the transition between a initial state of incident neutron and a final state of the gamma decay by means of a single many-body framework of the cRPA-TDDFT. With the cRPA approach, it is possible to describe various excitation modes present in the $(n, γ)$ reaction, including soft dipole excitation, the giant resonances as well as non-collective excitations and the single-particle resonances. Furthermore, it enables us to describe the $(n, γ)$ reaction where the final states of the gamma transition are low-lying surface vibrational states. We demonstrate the theory by performing numerical calculation for the reaction $^{139} Sn (n, γ)^{140} Sn$ . We discuss various new features which are beyond the single-particle model; presence of narrow and wide resonances originating from non-collective and collective excitations and roles of low-lying quadrupole and octupole vibrational states.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.09455 [pdf]
PRC(2023)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Early quark deconfinement in compact star astrophysics and heavy-ion collisions

ZRH22: An improved analysis of the pion-nucleon measurements at low energy

Dense Nuclear Matter with Baryon Overlap

Continuum random-phase approximation for (n,\gamma) reactions on neutron-rich nuclei: collective effects and resonances

Affiliations