Nuclear Theory·nucl-th

Monday·June 27, 2022

7 papers—4 primary·3 cross-listed

01
Quark anomalous magnetic moment leads to the inverse magnetic catalysis phenomena of chiral restoration and deconfinement phase transitions in $μ_{B} - T$ plane
Shijun Mao🇨🇳
The effect of quark anomalous magnetic moment (AMM) to chiral restoration and deconfinement phase transitions in baryon chemical potential-temperature $(μ_{B} - T)$ plane under magnetic fields is investigated in frame of a Pauli-Villars regularized PNJL model. It's found that the quark AMM plays the role of inverse catalysis to the phase transitions, and large quark AMM will change the magnetic catalysis phenomena of phase transitions to inverse magnetic catalysis in the whole $μ_{B} - T$ plane. For a fixed magnetic field, the critical temperature $T_{c}$ and critical baryon chemical potential $μ_{B}^{c}$ decreases with quark AMM. The stronger the magnetic field is, the inverse catalysis effect of AMM becomes more important. For a small AMM $κ = κ_{1}$ , it shows the magnetic catalysis effect for critical temperature $T_{c}$ at vanishing $μ_{B}$ with increasing magnetic field, and (inverse) magnetic catalysis effect for critical baryon chemical potential $μ_{B}^{c}$ at vanishing $T$ under (weak) strong magnetic field. At finite $T$ and $μ_{B}$ , there exist some crossings of the phase transition lines with different magnetic field. For a large AMM $κ = κ_{2}$ , we obtain the inverse magnetic catalysis effect in the whole $μ_{B} - T$ plane, and no crossings of phase transition lines happen.
nucl-thhep-phPRD(2022)·21 citations
02
Low-energy $^{7}$ Li( $n, γ$ ) $^{8}$ Li and $^{7}$ Be( $p, γ$ ) $^{8}$ B radiative capture reactions within the Skyrme Hartree-Fock approach
Le-Anh Nguyen · Minh-Loc Bui
The electromagnetic dipole transitions in $^{7}$ Be( $p, γ$ ) $^{8}$ B and $^{7}$ Li( $n, γ$ ) $^{8}$ Li reactions at the keV-energy region were analyzed simultaneously within the Skyrme Hartree-Fock potential model. The Skyrme Hartree-Fock calculation is adopted as a microscopic approach to obtain consistently the single-particle bound and scattering states in the calculation of the radial overlap function within the potential model. All non-resonant and resonant electromagnetic dipole transitions are taken into account. The electric dipole transitions are successfully described with the slightest adjustment. The resonant magnetic dipole transitions at $633$ keV and $2184$ keV of $^{7}$ Be( $p, γ$ ) $^{8}$ B reaction, and the one at $222$ keV of $^{7}$ Li( $n, γ$ ) $^{8}$ Li are also analyzed. The astrophysical $S_{17} (0)$ factor of $^{7}$ Be( $p, γ$ ) $^{8}$ B reaction is found to be $22.3$ eV\,b.
nucl-thPRC(2022)·9 citations
03
Fragment productions in DJBUU and SQMD: comparative study
Dae Ik Kim · Chang-Hwan Lee · Kyungil Kim · Youngman Kim · Sangyong Jeon
We study $^{208}$ Pb+ $^{40, 48}$ Ca reactions at $E_{beam}$ = 50, 100 AMeV with DJBUU and SQMD transport codes. We compare the large primary fragments from the two codes at the end of the simulation time. We observe that overall the two models produce similar fragments. However, we see a noticeable difference between DJBUU and SQMD at $E_{beam} = 100$ AMeV with the impact parameter $b$ = 0 fm and discuss this difference in terms of the difference in the equation of state adopted in the two models and the difference in stability inherent to the BUU-type and QMD-type models.
nucl-thJ.Korean Phys.Soc.(2022)·2 citations
04
Order-by-order Anisotropic Transport Coefficients of a Magnetised Fluid: a Chapman-Enskog Approach
Utsab Gangopadhyaya🇮🇳 · Victor Roy🇮🇳
We derive the first and second-order expressions for the shear, the bulk viscosity, and the thermal conductivity of a relativistic hot boson gas in a magnetic field using the relativistic kinetic theory within the Chapman-Enskog method. The order-by-order off-equilibrium distribution function is obtained in terms of the associate Laguerre polynomial with magnetic field-dependent coefficients using the relativistic Boltzmann-Uehling-Uhlenbeck transport equation. The order-by-order anisotropic transport coefficients are evaluated in powers of the dimensionless ratio of kinetic energy to the fluid temperature for finite magnetic fields. In a magnetic field, the shear viscosity (in all order) splits into five different coefficients. Four of them show a magnetic field dependence as seen in a previous study \cite{Ashutosh1} using the relaxation time approximation for the collision kernel. On the other hand, bulk viscosity, which splits into three components (in all order), is independent of the magnetic field. The thermal conductivity shows a similar splitting but is field-dependent. The difference in the first and second-order results are prominent for the thermal conductivities than the shear viscosity; moreover, the difference in the two results is most evident at low temperatures. The first and second-order results seem to converge rapidly for high temperatures.
nucl-thJHEP(2022)·3 citations
05
Configurational entropy as a probe of the stability condition of compact objects
P.S. Koliogiannis🇬🇷 · G.A. Tsalis🇬🇷 · C.P. Panos🇬🇷 · Ch.C. Moustakidis🇬🇷
We systematically extend the statement that the configurational entropy provides an alternative approach to studying gravitational stability of compact objects, carried out in the previous work of M. Gleiser and N. Jiang, Phys. Rev. D {\bf 92}, 044046 (2015). Inspired by that paper, we try to answer the crucial question: Is there any one-to-one correspondence between the minimum of the configurational entropy and the stability point for each realistic equation of state? In view of the above question, we focus on neutron stars, quark stars, as well as on the third family of compact stars (hybrid stars), where a possible phase transition may lead to the existence of twin stars (stars with equal mass but different radius). In each case, we use a large set of equations of state investigating the possibility to find correlations between the stability region obtained from the traditional perturbation methods to the one obtained by the minimum of configurational entropy. We found that the suggested prediction of the stability by the minimization of the configurational entropy, concerning neutron stars and quark stars, does not have, at least quantitatively, universal validity. However, in several cases it qualitatively predicts the existence of the stability point. In conclusion, the configurational entropy, can be considered as an additional tool which enters into the quiver for studying the stability of compact objects such as for example neutron and quark stars, but taking into account that the accuracy of the predictions depends on the specific character of each equation of state.
↳ gr-qcastro-ph.HEnucl-thphysics.comp-phPRD(2023)·10 citations
06
Analysis of one-neutron transfer reaction in $^{18}$ O + $^{76}$ Se collision at 275 MeV
I. Ciraldo🇮🇹 · F. Cappuzzello🇮🇹 · M. Cavallaro🇮🇹 · D. Carbone🇮🇹 · S. Burrello🇩🇪 · A. Spatafora🇮🇹 · A. Gargano🇮🇹 · G. De Gregorio🇮🇹 · R. I. Magaña Vsevolodovna🇮🇹 · L. Acosta🇲🇽 · C. Agodi🇮🇹 · P. Amador-Valenzuela🇧🇷 and 36 other authors
Purpose: We want to analyze transitions to low-lying excited states of the residual and ejectile nuclei in the 76Se(18O, 17O) 77Se one-neutron stripping reaction at 275-MeV incident energy and determine the role of single-particle and core excitation in the description of the measured cross sections. In addition, we explore the sensitivity of the calculated cross section to different nuclear structure models. Methods: The excitation energy spectrum and the differential cross-section angular distributions are measured using the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles and the missing mass technique for the reconstruction of the reaction kinematics. The data are compared with calculations based on distorted-wave Born approximation, coupled-channels Born approximation, and coupled reaction channels adopting spectroscopic amplitudes for the projectile and target overlaps derived by large-scale shell-model calculations and interacting boson-fermion model. Results: Peaks in the energy spectra corresponding to groups of unresolved transitions to 77Se and 17O are identified. The experimental cross sections are extracted and compared to theoretical calculations. A remarkable agreement is found, without using any scaling factors, demonstrating that the adopted models for nuclear structure and reaction take into account the relevant aspects of the studied processes. The main transitions which contribute to the cross section of each peak are identified.
↳ nucl-exnucl-thPRC(2022)·34 citations
07
Thermalization of gluons in spatially homogeneous systems
Sergio Barrera Cabodevila🇪🇸 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸
We investigate thermalization of gluons in spatially homogeneous systems using the Boltzmann equation in diffusion approximation. A complete picture on thermalization is obtained for both initially under- and over-populated systems. In an initially under-populated system, we find that its soft sector undergoes three stages: overheating, cooling/overcooling and reheating before full thermalization is achieved. In an initially over-populated system, we find that its soft sector only undergoes two stages towards full thermalization: overheating and cooling. The cooling stage is consistently driven by momentum broadening due to multiple elastic collisions, manifest as a non-thermal scaling solution.
↳ hep-phnucl-thPLB(2022)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quark anomalous magnetic moment leads to the inverse magnetic catalysis phenomena of chiral restoration and deconfinement phase transitions in μB​−T plane

Low-energy 7Li(n,γ)8Li and 7Be(p,γ)8B radiative capture reactions within the Skyrme Hartree-Fock approach

Fragment productions in DJBUU and SQMD: comparative study

Order-by-order Anisotropic Transport Coefficients of a Magnetised Fluid: a Chapman-Enskog Approach

Configurational entropy as a probe of the stability condition of compact objects

Analysis of one-neutron transfer reaction in 18O + 76Se collision at 275 MeV

Thermalization of gluons in spatially homogeneous systems

Affiliations

Quark anomalous magnetic moment leads to the inverse magnetic catalysis phenomena of chiral restoration and deconfinement phase transitions in $μ_{B} - T$ plane

Low-energy $^{7}$ Li( $n, γ$ ) $^{8}$ Li and $^{7}$ Be( $p, γ$ ) $^{8}$ B radiative capture reactions within the Skyrme Hartree-Fock approach

Analysis of one-neutron transfer reaction in $^{18}$ O + $^{76}$ Se collision at 275 MeV