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
05
[Submitted on 28 Mar 2023] (cross-list from hep-ph)
High-energy dipole scattering amplitude from evolution of low-energy proton light-cone wave functions
Adrian Dumitru🇺🇸 · Heikki Mäntysaari🇫🇮 · Risto Paatelainen🇫🇮
The forward scattering amplitude of a small dipole at high energies is given in the mean field approximation by the Balitsky-Kovchegov (BK) evolution equation. It requires an initial condition $N (r; x_{0})$ describing the scattering of a dipole with size $r$ off the target that is probed at momentum fraction $x_{0}$ . Rather than using ad hoc parameterizations tuned to high-energy data at $x ≪ x_{0}$ , here we attempt to construct an initial scattering amplitude that is consistent with low-energy, large- $x$ properties of the proton. We start from a non-perturbative three quark light-cone model wave function from the literature. We add $O (g)$ corrections due to the emission of a gluon, and $O (g^{2})$ virtual corrections due to the exchange of a gluon, computed in light-cone perturbation theory with exact kinematics. We provide numerical data as well as analytic parameterizations of the resulting $N (r; x_{0})$ for $x_{0} = 0.01 - 0.05$ . Solving the BK equation in the leading logarithmic (LL) approximation towards lower $x$ , we obtain a fair description of the charm cross section in deeply inelastic scattering measured at HERA by fitting one parameter, the coupling constant $α_{s} ≃ 0.2$ . However, without the option to tune the initial amplitude at $x_{0}$ , the fit of the high precision data results in $χ^{2} / N_{dof} = 2.3$ at $N_{dof} = 38$ , providing clear statistical evidence for the need of systematic improvement e.g. of the photon wave function, evolution equation, and initial condition.
Comments:
11 pages, 10 figures. Obtained dipole-proton amplitudes at different x are included in the ancillary files, v2 matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2303.16339 [pdf]
PRD(2023)·15 citations
06
[Submitted on 29 Mar 2023] (cross-list from quant-ph)
Degeneracy in excited-state quantum phase transitions of two-level bosonic models and its influence on system dynamics
J. Khalouf-Rivera · Qian Wang · Lea F. Santos · J.E. García Ramos · M. Carvajal · F. Pérez-Bernal
Excited-state quantum phase transitions (ESQPTs) strongly influence the spectral properties of collective many-body quantum systems, changing degeneracy patterns in different quantum phases. Level degeneracies, in turn, affect the system's dynamics. We analyze the degeneracy dependence on the size of two-level boson models with a $u (n + 1)$ dynamical algebra, where $n$ is the number of collective degrees of freedom. Below the ESQPT critical energy of these models, the energy gap between neighboring levels that belong to different symmetry sectors gets close to zero as the system size increases. We report and explain why this gap goes to zero exponentially for systems with one collective degree of freedom, but algebraically in models with more than one degree of freedom. As a consequence, we show that the infinite-time average of out-of-time-order correlators is an ESQPT order parameter in finite systems with $n = 1$ , but in systems with $n > 1$ , this average only works as an order parameter in the mean-field limit.
Subjects:
Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
arXiv:
2303.16551 [pdf]
PRA(2024)·8 citations
07
[Submitted on 29 Mar 2023] (cross-list from hep-ph)
Heavy quarkonium with finite three momentum near $T_{c}$
HyungJoo Kim🇰🇷 · Seokwoo Yeo🇰🇷 · Sungtae Cho🇰🇷 · Su Houng Lee🇰🇷
We investigate the non-trivial 3-momentum effects on the masses of heavy quarkonium states that are moving in a hot medium using QCD sum rules. For all charmonium states, we observe a negative mass shift near $T_{c}$ that is less than 3 $%$ at a momentum of 1 $GeV$ . Specifically, we first investigate the difference between the longitudinal and transverse modes of both $J / ψ$ and $χ_{c 1}$ . We find that the transverse mode of the $J / ψ$ experiences larger modification than the longitudinal mode, while the $χ_{c 1}$ has the opposite behavior. By comparing the $η_{c}$ and $χ_{c 0}$ , and also the unpolarized $J / ψ$ and $χ_{c 1}$ , we recognize that the P-wave particles have stronger momentum dependencies on their masses than the S-wave ones. We also find $Υ$ (1S) has negligible 3-momentum dependence compared to the charmonium states, e.g. less than 0.01 $%$ even at 1.4 $T_{c}$ and at a momentum of 4 $GeV$ .
Comments:
6 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2303.16731 [pdf]
PRD(2023)·3 citations
08
[Submitted on 29 Mar 2023] (cross-list from hep-ph)
Effects of finite volume and magnetic fields on thermodynamic properties of quark matter and fluctuations of conserved charges
Nisha Chahal🇮🇳 · Suneel Dutt🇮🇳 · Arvind Kumar🇮🇳
In the current work, we present the influence of finite volume and magnetic field on the thermodynamic properties of isospin asymmetric quark matter using the Polyakov loop extended chiral SU(3) quark mean field (PCQMF) model at finite chemical potential and temperature. Within the PCQMF model, we use the scalar and vector field values in mean-field approximation to obtain the thermodynamic properties: pressure density, entropy density and energy density. The susceptibilities of conserved charges for strongly interacting matter for different system sizes as well as for different values of the magnetic field have been studied. A sizable shift in phase boundary towards the higher values of quark chemical potential ( $μ_{q}$ ) and temperature (T) has been observed for decreasing values of system volume as well as an opposite shift towards lower temperature and quark chemical potential for increasing magnetic field. We observe an enhancement in fluctuations of conserved charges in the regime of the transition temperature. These studies may have a significant role in understanding the thermodynamic observables extracted from heavy-ion collisions data.
Comments:
42 pages, 15 figures (Accepted for publication in Physical Review C)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2303.16840 [pdf]
PRC(2023)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE