Nuclear Theory·nucl-th

Wednesday·August 23, 2023

9 papers—6 primary·3 cross-listed

01
Exploring Rapidity-Even Dipolar Flow in Isobaric Collisions at RHIC
Niseem Magdy🇺🇸 · Roy Lacey🇺🇸
Employing the AMPT transport model, we investigate the response of the rapidity-even dipolar flow ( $v_{1}^{even}$ ) and its associated Global Momentum Conservation (GMC) parameter $K$ to structural disparities within $^{96}$ Ru and $^{96}$ Zr nuclei. We analyze $Ru + Ru$ and $Zr + Zr$ collisions at a center-of-mass energy of $s_{N N}$ = 200 GeV. Our analysis demonstrates that the eccentricity $ε_{1}$ , $v_{1}^{even}$ and $K$ exhibit subtle yet discernible sensitivity to the input nuclear structure distinctions between $^{96}$ Ru and $^{96}$ Zr isobars. This observation suggests that measuring $v_{1}^{even}$ and the GMC parameter in these isobaric collisions could serve as a means to fine-tune the comprehension of their nuclear structure disparities and offer insights to enhance the initial condition assumptions of theoretical models.
nucl-thnucl-exJ.Phys.G(2024)·3 citations
02
Emerging {\gamma}-soft-like spectrum in 196Pt in the SU3-IBM (I)
Tao Wang · Bing-cheng He · Chun-xiao Zhou · Dong-kang Li · Lorenzo Fortunato
Recently, it has been argued that a spherical-like spectrum emerges in the SU3-IBM, opening up new approaches to understand the {\gamma}-softness in realistic nuclei. In a previous paper, {\gamma}-softness with degeneracy of the ground and quasi-{\gamma} bands was observed. In this paper, another special point connected with the middle degenerate point is discussed, which is found to be related with the properties of 196Pt. This emergent {\gamma}-softness has also been shown to be important for understanding the prolate-oblate asymmetric shape phase transition. The low-lying spectra, B(E2) values and quadrupole moments in 196Pt are discussed showing that the new model can account for several observed features. This is the first part of the discussions on the {\gamma}-soft-like spectrum of 196Pt.
nucl-thCPC(2024)·13 citations
03
Constructing Inverse Scattering Potentials for {\alpha}-{\alpha} System using Reference Potential Approach
O. S. K. S. Sastri · Arushi Sharma · Ayushi Awasthi
Background: An accurate way to incorporate long range Coulomb interaction alongside short-range nuclear interaction has been a challenge for theoretical physicists. Purpose: In this paper, we propose a methodology based on the reference potential approach for constructing inverse potentials of alpha-alpha scattering. Methods: Two smoothly joined Morse potentials, regular for short-range nuclear interaction and inverted for long range Coulomb, are used in tandem as a reference potential in the phase function method to obtain the scattering phase shifts for the S, D and G states of alpha-alpha scattering. The model parameters are optimized by choosing to minimize the mean absolute percentage error between the obtained and experimental scattering phase shift values. Results: The constructed inverse potentials for S, D and G states have resulted in mean absolute percentage errors of 0.8, 0.5, and 0.4 respectively. The obtained resonances for D and G states closely match the experimental ones. Conclusion: The reference potential approach using a combination of smoothly joined Morse functions is successful in accurately accounting for the Coulomb interaction between charged particles in nuclear scattering studies.
nucl-thPRC(2024)·14 citations
04
Stellar weak-interaction rates for $r p$ -process waiting-point nuclei from projected shell model
Zi-Rui Chen · Long-Jun Wang
We propose a projected shell model (PSM) for description of stellar weak-interaction rates between even-even and odd-odd nuclei with extended configuration space where up to six-quasiparticle (qp) configurations are included, and the stellar weak-interaction rates for eight $r p$ -process waiting-point (WP) nuclei, $^{64}$ Ge, $^{68}$ Se, $^{72}$ Kr, $^{76}$ Sr, $^{80}$ Zr, $^{84}$ Mo, $^{88}$ Ru and $^{92}$ Pd, are calculated and analyzed for the first time within the model. Higher-order qp configurations are found to affect the underlying Gamow-Teller strength distributions and the corresponding stellar weak-interaction rates. Under $r p$ -process environments with high temperatures and densities, on one hand, thermal population of excited states of parent nuclei tends to decrease the stellar $β^{+}$ decay rates. On the other hand, the possibility of electron capture (EC) tends to provide increasing contribution to the rates with temperature and density. The effective half-lives of WP nuclei under the $r p$ -process peak condition are predicted to be reduced as compared with the terrestrial case, especially for $^{64}$ Ge and $^{68}$ Se.
nucl-thPLB(2024)·15 citations
05
Nuclear $β$ spectrum from projected shell model (I): allowed one-to-one transition
Fan Gao🇨🇳 · Zi-Rui Chen🇨🇳 · Long-Jun Wang🇨🇳
Nuclear $β$ spectrum and the corresponding (anti-)neutrino spectrum play important roles in many aspects of nuclear astrophysics, particle physics, nuclear industry and nuclear data. In this work we propose a projected shell model (PSM) to calculate the level energies as well as the reduced one-body transition density (ROBTD) by the Pfaffian algorithm for nuclear $β$ decays. The calculated level energies and ROBTD are inputed to the Beta Spectrum Generator (BSG) code to study the high precision $β$ spectrum of allowed one-to-one transitions. When experimental level energies are adopted, the calculated $β$ spectrum by ROBTD of the PSM deviates from the one by the extreme simple particle evaluation of the BSG by up to $10%$ , reflecting the importance of nuclear many-body correlations. When calculated level energies are adopted, the calculated $β$ spectrum shows sensitive dependence on the reliability of calculated level energies. The developed method for ROBTD by the PSM will also be useful for study of the first-forbidden transitions, the isovector spin monopole resonance etc. in a straightforward way.
nucl-thPRC(2023)·6 citations
06
Momentum dependent measures of correlations between mean transverse momentum and harmonic flow in heavy ion collisions
Rupam Samanta🇵🇱 · Piotr Bozek🇵🇱
The correlation between the mean transverse momentum and the harmonic flow coefficients is an observable which is of great interest; it is sensitive to shape fluctuations in the initial state of a relativistic nuclear collision. The measurement of that correlation coefficient in central collisions allows one to infer about the intrinsic deformation of the colliding nuclei. We propose to study the momentum dependent covariance and correlation coefficient between the mean transverse momentum and the harmonic flow in a given transverse momentum bin. Two possible constructions of such observables are provided and predictions are obtained from a viscous hydrodynamic model. We find that such momentum dependent correlation coefficients between the mean transverse momentum and the harmonic flow show a strong and nontrivial momentum dependence. We also explore the effects of granularity (nucleon width) in the initial state, the nuclear deformation, and the shear viscosity on this momentum dependent correlation coefficient. The shape of the momentum dependence of the correlation coefficient for the triangular flow is found to be sensitive to the size of small scale fluctuations in the initial state. On the other hand, the shape of the momentum dependence of the covariance between the mean transverse momentum and the harmonic flow coefficients is found to be sensitive to the value of the shear viscosity and to the granularity of the initial state.
nucl-thhep-phnucl-exPRC(2024)·5 citations
07
On scattering problem off the potential, decreasing as inverse square of distance
V. A. Gradusov · S. L. Yakovlev
A solution of the scattering problem is obtained for the Schrödinger equation with the potential of induced dipole interaction, which decreases as the inverse square of the distance. Such a potential arises in the collision of an incident charged particle with a complex of charged particles (for example, in the collision of electrons with atoms). For the wave function, an integral equation is constructed for an arbitrary value of the orbital momentum of relative motion. By solving this equation, an exact integral representation for the $K$ -matrix of the problem is obtained in terms of the wave function. This representation is used to analyze the behavior of the $K$ -matrix at low energies and to obtain comprehensive information on its threshold behavior for various values of the dipole momentum. The resulting solution is applied to study the behavior of the scattering cross sections in the electron, positron and antiproton system.
↳ physics.atom-phmath-phmath.MPnucl-thTheor.Math.Phys.(2023)·2 citations
08
AdS/CFT and the Double-Copy: A Unified Perspective Across Various Phenomenological Models
Jia-rui Guo🇨🇳
This study utilizes theoretical tools including the double copy relation and AdS/CFT correspondence. Applying analogies, we establish a system to discuss the associations and equivalence relations among QCD, QED, and various (mixed) gauge field theory based quantum many-body effective models. By employing mathematical techniques on the background spacetime, these relations are extended to extreme regimes while ensuring model independence.
↳ hep-phnucl-th0 citations
09
Universality in quasinormal modes of neutron stars with quark-hadron crossover
Hajime Sotani🇯🇵 · Toru Kojo🇯🇵
We examine the gravitational wave frequencies of the fundamental ( $f$ -) and 1st pressure ( $p_{1}$ -) modes excited in the neutron star models constructed with the quark-hadron crossover (QHC) type equations of state (EOS). We find that the $f$ -mode frequencies with QHC EOS basically are smaller and the $p_{1}$ -mode frequencies with QHC EOS are larger than those with hadronic EOS, focusing on the neutron star model with a fixed mass. We also find that the universality in the $f$ -mode frequencies multiplied by the stellar mass as a function of the stellar compactness or as a function of the dimensionless tidal deformability, which is derived with various hadronic EOSs, can keep even with QHC EOS. That is, using these universal relations, one cannot distinguish QHC EOS from hadronic EOSs. Instead, using the relations one can extract the stellar radii whose evolution from low to high mass neutron stars can differentiate QHC from hadronic EOSs. On the other hand, we find that the $p_{1}$ -mode frequencies multiplied by the stellar mass with QHC EOS significantly deviate in a certain mass range from the corresponding empirical relations derived with various hadronic EOSs, with which one may distinguish QHC EOS from hadronic EOSs.
↳ astro-ph.HEnucl-thPRD(2023)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE