Nuclear Theory·nucl-th

Thursday·March 30, 2023

8 papers—4 primary·4 cross-listed

01
[Submitted on 29 Mar 2023]
Effect of Coriolis force on the shear viscosity of quark matter: A nonrelativistic description
Cho Win Aung🇮🇳 · Ashutosh Dwibedi🇮🇳 · Jayanta Dey🇮🇳 · Sabyasachi Ghosh🇮🇳
Shear viscosity becomes anisotropic in a rotating medium. It is discovered here that for rotating thermalized quantum systems such as those created in relativistic heavy-ion collisions, the coeffficient of shear viscosity breaks up into five independent components. Similar phenomena were also discovered for quark-gluon plasma in the presence of the magnetic field. Like the Lorentz force at a finite magnetic field, the Coriolis force also creates anisotropic viscosity at nonzero rotation. As a first approach, for simplicity, the calculations are done in the nonrelativistic prescription, with a future proposal to extend it toward a relativistic description. Introducing the Coriolis force term in relaxation time approximated Boltzmann transport equation, we have found different effective relaxation times along the parallel, perpendicular, and Hall directions in terms of actual relaxation time and rotating time period. Comparing the present formalism with the finite magnetic field picture, we have shown the equivalence of roles between the rotating and cyclotron time periods, where the rotating time period is inverse of twice the angular velocity.
Comments:
11 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2303.16462 [pdf]
PRC(2024)·11 citations
02
[Submitted on 29 Mar 2023]
Low-energy quadrupole collectivity of Sn nuclei in self-consistent calculations with a semi-realistic interaction
Y. Omura · H. Nakada · K. Abe · M. Takahashi
Quadrupole collectivity of the lowest-lying states, focusing on $E_{x} (2_{1}^{+})$ and $B (E 2; 0_{1}^{+} \to 2_{1}^{+})$ , have been investigated for the $N = 50 - 82$ Sn nuclei by applying the self-consistent approaches with the semi-realistic interaction M3Y-P6. Both $E_{x} (2_{1}^{+})$ and $B (E 2; 0_{1}^{+} \to 2_{1}^{+})$ are well reproduced by the spherical Hartree-Fock-Bogolyubov (HFB) plus quasiparticle random-phase approximation (QRPA) calculations in $N \geq 64$ , without adjustable parameters. The measured $B (E 2)$ values in the neutron-deficient Sn nuclei cast a puzzle. In $54 \leq N \leq 62$ , the spherical HFB\,+\,QRPA calculations give too strong $B (E 2)$ , opposite to the shell-model predictions within the one major shell. Via the constrained-HFB (CHFB) calculations, it is found that the neutron-deficient Sn nuclei are soft against the quadrupole deformation, accounting for the limited applicability of the HFB\,+\,QRPA approach. In particular, the potential energy curves (PECs) are almost flat in the range of $∣ q_{0} ∣ ≲ 200 fm^{2}$ in $^{106 - 110}$ Sn. We confirm that the near degeneracy of $n 0 g_{7/2}$ and $n 1 d_{5/2}$ triggers weak quadrupole deformation and its balance with the pairing makes PECs flat, which is qualitatively consistent with a recent shell model result in an extended model space, by the calculations shifting the single-particle energy spacing and the pairing strength. These conclusions are supported by the proton-to-neutron ratios of the transition matrix elements and the reference values of $B (E 2)$ with the angular-momentum projection on top of the CHFB solutions.
Comments:
25 pages including 10 figures. To be published in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.16483 [pdf]
PRC(2023)·3 citations
03
[Submitted on 29 Mar 2023]
Schematic model for induced fission in a configuration-interaction approach
K. Uzawa · K. Hagino
We model fission at barrier-top energies in a simplified model space that permits comparison of different components of the residual nucleon-nucleon interaction. The model space is built on particle-hole excitations of reference configurations. These are Slater determinants of uniformly spaced orbitals characterized only by their quantum numbers and orbital energies. The residual interaction in the Hamiltonian includes the diabatic interaction connecting similar orbitals at different deformations, the pairing interaction between like nucleons, and a schematic off-diagonal neutron-proton interaction. We find that the fission reaction probability is sensitive to the off-diagonal neutron-proton interaction much more than to the pairing and the diabatic interactions. In particular, the transmission coefficients become insensitive to th e strength of the pairing interaction when the neutron-proton interaction is large. We also find that the branching ratio is insensitive to the final-state scission dynamics, as is assumed in the well-known Bohr-Wheeler theory.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.16488 [pdf]
PRC(2023)·7 citations
04
[Submitted on 29 Mar 2023]
Dynamically screened strongly quantized electron transport in binary neutron-star merger
Sreemoyee Sarkar🇮🇳 · Souvik Priyam Adhya🇵🇱
We examine electron-transport coefficients in magnetized hot and dense electron-ion plasma relevant in binary neutron star merger simulation. We calculate electrical and thermal conductivities in low density, high temperature, highly magnetized plasma of binary neutron star mergers where quantum oscillatory behavior of electrons emerge. For pronounced thermodynamic effects, we consider zeroth Landau level population of electrons for the calculation of conductivity. We solve Boltzmann equation in presence of magnetic field to obtain the dissipative components of electrical and thermal conductivities. The dissipative coefficients are formulated considering frequency dependent dynamical screening in the quantized electron-ion scattering rate. Numerical estimations show that the effect of dynamical screening of photon propagator on electrical and thermal conductivities is pronounced. We observe that dynamical screening reduces the maxima of both the electrical and thermal conductivities by factors of thirty one and twenty respectively leading to a reduction in the corresponding time scales of these coefficients. The common scaling factor between electrical and thermal conductivity is also observed to follow cubic relationship with temperature violating Wiedemann-Franz law.
Comments:
Accepted in The European Physical Journal C. arXiv admin note: substantial text overlap with arXiv:2108.11878
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2303.16811 [pdf]
EPJC(2023)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Effect of Coriolis force on the shear viscosity of quark matter: A nonrelativistic description

Low-energy quadrupole collectivity of Sn nuclei in self-consistent calculations with a semi-realistic interaction

Schematic model for induced fission in a configuration-interaction approach

Dynamically screened strongly quantized electron transport in binary neutron-star merger

Affiliations