PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·August 22, 2023

15 papers—7 primary·8 cross-listed

All15Primary7Cross-lists8
  1. 01

    Comparisons and Predictions for Collisions of deformed U nuclei at GeV

    Nicolas Fortier🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    We present comparisons to experimental data along with predictions of observables for U+U collisions at 193 GeV using a multistage theoretical and computational framework consisting of boost-invariant IP-Glasma initial state, MUSIC hydrodynamics, and a hadronic transport cascade generated by iS3D \& SMASH. Our results show great agreement with existing anisotropic flow measurements from RHIC [ arXiv:1505.07812 ; arXiv:1901.08155 ] . We provide predictions for differential flow observables as well as multiparticle correlations and transverse-momentum-flow correlations. When possible, we compare our predictions to results from Au+Au collisions at 200 GeV to properly outline the effects of deformation in the initial state on final state observables.

    nucl-thhep-phPRC(2025)·18 citations
  2. 02

    Modified Urca neutrino emissivity at finite temperature

    Lami Suleiman🇫🇷 · Micaela Oertel🇫🇷 · Marco Mancini🇫🇷

    Charged current neutrino-nucleon reactions, generally called Urca processes, are crucial actors of a neutron star's thermal evolution. The so-called direct processes show a pronounced threshold under which the reaction is kinematically suppressed. This suppression does not apply to "modified" Urca processes which involve interaction with an additional nucleon. Calculations of the modified Urca neutrino rates were established for cold neutron star matter and for dilute hot matter, in both cases under strong assumptions. In this paper, we revise the calculations of the modified Urca neutrino rates for dense and hot matter, and for different compositions. We study the influence of different approximations used in previous computations. We derive expressions for the rates of modified Urca neutrino emissivity within thermal field theory and perform the phase space integration numerically using mainly importance sampling Monte-Carlo techniques. The neutrino emissivity of modified and direct processes are established and compared. We find in particular that the modified Urca process is not necessarily suppressed with respect to the direct process above the threshold of the latter at moderate densities and temperatures, in contrast to what is generally assumed. Numerical results are confirmed by an estimation of the ratio of modified to direct Urca rates with a simple analytic approximation, thereby showing the regimes of suppression for the modified processes depending on temperature and density. These results show that modified Urca rates have to be considered carefully upon evaluating neutrino opacities in dense and warm matter.

    nucl-thastro-ph.HEPRC(2023)·15 citations
  3. 03

    Microscopic triaxial cranking model: preliminary predictions for oscillator potential and light nuclei

    Parviz Gulshani · Alaaddine Lahbas

    The conventional cranking model for uniaxial and triaxial rotation (CCRM3) is frequently used to study rotational features in deformed nuclei. However, CCRM3 is semi-classical and phenomenological because it uses a constant angular velocity, resulting in a number of Hamiltonian symmetry breakings. To investigate the effect of a dynamic angular velocity, a quantal, microscopic, D2, signature, and time-reversal invariant cranking model for triaxial rotation (MSCRM3) is derived exactly from a unitary rigid-flow-velocity-field rotation transformation of the nuclear Schrodinger equation and Hartree-Fock method. Except for a microscopically-determined angular velocity and normally-small residual terms, the MSCRM3 and CCRM3 Schrodinger equations are identical in form. The microscopic angular velocity emerges from the HF variation, and the residual terms may become significant for triaxial rotation at high spins and in back-bending regions where and undergo large changes. A preliminary application of MSCRM3 and CCRM3 to the light nuclei 20Ne, 24Mg, and 28Si using the simple self-consistent deformed harmonic oscillator potential predicts some interesting differences between the rotational features and phenomena predicted by the two models. These differences are attributable to the impact of the dynamic angular velocity. It is important to investigate and understand these differences for the simple and realistic nuclear interactions.

    nucl-th0 citations
  4. 04

    Nuclear level density in the statistical semiclassical micro-macroscopic approach

    A.G. Magner · A.I. Sanzhur · S.N. Fedotkin · A.I. Levon · U.V. Grygoriev · S. Shlomo

    Level density is derived for a finite system with strongly interacting nucleons at a given energy E, neutron N and proton Z particle numbers, projection of the angular momentum M, and other integrals of motion, within the semiclassical periodic-orbit theory (POT) beyond the standard Fermi-gas saddle-point method. For large particle numbers, one obtains an analytical expression for the level density which is extended to low excitation energies U in the statistical micro-macroscopic approach (MMA).The interparticle interaction averaged over particle numbers is taken into account in terms of the extended Thomas-Fermi component of the POT. The shell structure of spherical and deformed nuclei is taken into account in the level density. The MMA expressions for the level density reaches the well-known macroscopic Fermi-gas asymptote for large excitation energies U and the finite combinatoric power-expansion limit for low energies U. We compare our MMA results for the averaged level density with the experimental data obtained from the known excitation energy spectra by using the sample method under statistical and plateau conditions. Fitting the MMA to these experimental data on the averaged level density by using only one free physical parameter - inverse level density parameter K - for several nuclei and their long isotope chain at low excitation energies U, one obtains the results for K. These values of K might be much larger than those deduced from neutron resonances. The shell, isotopic asymmetry, and pairing effects are significant for low excitation energies.

    nucl-thNucl.Phys.Atom.Energy(2023)·1 citation
  5. 05

    Transverse and non-boost longitudinal expansion of (2+1)dimensional relativistic ideal-hydrodynamics flow in heavy ion collisions

    M. Karimabadi🇮🇷 · A.F. Kord🇮🇷 · B. Azadegan🇮🇷

    This study investigates the evolution of quark gluon plasma (QGP) within a generalized Bjorken flow framework. The medium under consideration is assumed to possess a finite transverse size and to expand both radially and along the beam axis. However, we assume that the boost invariance of longitudinal expansion is broken. To be more specific, we generalize the Bjorken solution to include the acceleration and transverse expansion of the fluid. We analytically study the (2 + 1) dimensional longitudinal acceleration expansion of hot and dense quark matter, applying a perturbation approach to solve the relativistic hydrodynamics equations. This procedure enables us to obtain exact algebraic expressions for fluid velocities and energy densities in both transverse and longitudinal directions. To simplify our calculations, we assume that the fluid is produced in central collisions, and therefore, we consider azimuthal symmetry. We compare the radial velocity and correction energy density with those obtained from the Gubser model. Furthermore, we determine the fluid's acceleration parameter and longitudinal correction energy density, which exhibits a Gaussian distribution.

    nucl-thhep-th0 citations
  6. 06

    Strangeness production in neutron star matter

    Gao-Chan Yong🇨🇳

    Based on a dynamical model on particle production, the production and fraction of exotic components in neutron star matter are analyzed. It is found that there exists a small fraction of strangeness in twice saturation density matter. For five times saturation density matter, the fraction of strange baryons can be as high as 25-50\%, depending on the equation of state used. The neutron-proton asymmetry of dense matter does not significantly impact the strangeness fraction in neutron star matter. This research provides new insights into the strange components in neutron stars.

    nucl-thhep-phPRD(2023)·4 citations
  7. 07

    A novel method for calculating Bose-Einstein correlation functions with Coulomb final-state interaction

    Márton Nagy🇭🇺 · Aletta Purzsa🇭🇺 · Máté Csanád🇭🇺 · Dániel Kincses🇭🇺

    Measurements of Bose-Einstein correlations played a crucial role in the discovery and the subsequent detailed exploration of the Quark-Gluon-Plasma (QGP) created in high-energy collisions of heavy nuclei. Such measurements gave rise to femtoscopy, a flourishing sub-field of high-energy physics, and there are important new directions to explore and discoveries to be made in the near future. One of these important current topics is the precise investigation of the shape of the correlation functions utilizing Lévy-stable sources. In this paper, we present a novel method of calculating the shape of the two-particle correlation functions, including the Coulomb final-state interaction. This method relies on an exact calculation of a large part of the necessary integrals of the Coulomb wave function and can be utilized to calculate the correlation function for any source function with an easily accessible Fourier transform. In this way, it is eminently applicable to Lévy-stable source functions. In this particular case, we find that the new method is more robust and allows the investigation of a wider parameter range than the previously utilized techniques. We present an easily applicable software package that is ready to use in experimental studies.

    nucl-thhep-exhep-phnucl-exEPJC(2023)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE