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Nuclear Theory·nucl-th

Tuesday·May 10, 2022

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    A new class of hybrid EoS with multiple critical endpoints for simulations of supernovae, neutron stars and their mergers

    Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱

    We introduce a family of equations of state (EoS) for hybrid neutron star (NS) matter that is obtained by a two-zone parabolic interpolation between a soft hadronic EoS at low densities and a stiff quark matter EoS with color superconductivity at high densities within a finite region of baryonic chemical potentials . We consider two scenarios corresponding to a cross-over and a strong first-order transition between quark and hadron phases considered at finite and zero temperatures. This allows us to analyze the effects of finite entropy on the EoS and mass-radius relation of NS. We demonstrate that the formation of a color superconducting state of quark matter drives the evolution of matter in supernovae explosions under the condition of entropy conservation to higher temperatures than in the case of deconfinement to normal quark matter. Within the presented hybrid EoS scenario, regions of the QCD phase diagram may be accessible to supernovae and NS mergers that can be reached also in terrestrial experiments with relativistic heavy ion collisions.

    nucl-thastro-ph.HEhep-phEPJA(2022)·28 citations
  2. 02

    Phases of Quench Dynamics in the Presence of Fluctuation

    Chang Lei🇨🇳 · Shu Lin🇨🇳

    We study the effect of thermal fluctuations on a sourced quench in a system with symmetry. By ignoring the fluctuation of finite momentum modes and tracing the dynamics of zero momentum mode driven by a spatially homogeneous source near the critical point, we map out a phase diagram for the quench dynamics. The phase diagram consists of three different phases. Phase I occurs for large fluctuations with the relaxation time set by fluctuation induced inverse effective mass square. Phase II occurs for small fluctuation and slow quench rate. The dynamics is characterized by a modified Kibble-Zurek scaling. Phase III corresponds to small fluctuations and rapid quench rate. The relaxation time tends to a finite value in the rapid quench limit. We also estimate the fluctuations of finite momentum modes, finding significant enhancement of the effective mass square. We speculate the qualitative features of the phase diagram may remain the same, but enhanced fluctuations can lead to shrinkage of phase II and III.

    nucl-thcond-mat.supr-conhep-phPRResearch(2023)·0 citations
  3. 03

    Spectral function for He using the Chebyshev expansion in coupled-cluster theory

    J. E. Sobczyk🇩🇪 · S. Bacca🇩🇪 · G. Hagen🇺🇸 · T. Papenbrock🇺🇸

    We compute spectral function for He by combining coupled-cluster theory with an expansion of integral transforms into Chebyshev polynomials. Our method allows to estimate the uncertainty of spectral reconstruction. The properties of the Chebyshev polynomials make the procedure numerically stable and considerably lower in memory usage than the typically employed Lanczos algorithm. We benchmark our predictions with other calculations in the literature and with electron scattering data in the quasi-elastic peak. The spectral function formalism allows one to extend ab-initio lepton-nucleus cross sections into the relativistic regime. This makes it a promising tool for modeling this process at higher energy transfers. The results we present open the door for studies of heavier nuclei, important for the neutrino oscillation programs.

    nucl-thhep-phPRC(2022)·12 citations
  4. 04

    The Big Bang Nucleosynthesis abundances of the light elements using improved thermonuclear reaction rates

    Chen Wu

    Big Bang Nucleosynthesis (BBN) is an important stage of a homogeneous and isotropic expanding universe. The results of calculation of the synthesis of light elements during this epoch can then be compared with the abundances of the light elements. The theoretical calculation of the BBN model depends on the initial conditions of the early universe and reaction cross sections measured by the nuclear physics experiment. Recently, an update of the NACRE (Nuclear Astrophysics Compilation of REactions) database is presented. This improved compilation comprises thermonuclear reaction rates for 34 two-body reactions on light nuclides (fifteen are particle transfer reactions and nineteen are radiative capture reactions). In this work, we calculate the BBN abundances by using these updated thermonuclear reaction rates in the framework of the code \texttt{AlterBBN}. Our results suggest that the new numerical result of the primordial Lithium abundance is 7.1 percent larger than the previous calculation.

    nucl-thGen.Rel.Grav.(2023)·2 citations
  5. 05

    Azimuthal-sensitive three-dimensional HBT radius in Au-Au collisions at GeV by the IQMD model

    Ling-Meng Fang🇨🇳 · Yu-Gang Ma🇨🇳 · Song Zhang🇨🇳

    We used an Isospin dependent Quantum Molecular Dynamics (IQMD) model to simulate Au + Au collisions at beam energy = 1.23 GeV, which corresponds to center of mass energy GeV. Firstly, we obtained reasonable rapidity and transverse mass spectra of and as well as "apparent" temperature parameters in comparison with the HADES data. Then by calculating three-dimensional Hanbury Brown and Twiss (HBT) radius of same charged pion-pairs, we obtained the square difference of outward radius and sideward radius, i.e. , as well as the freeze-out volume (), which were basically consistent with the trend of HADES experimental results. The azimuthal dependence of the HBT radii was also calculated by a matrix method, and corrected by the rotation matrix. In addition, the eccentricities of the - and - planes of pion-pair emissions were also extracted for different pair transverse momentum and collision centrality, which show that the -eccentricity increases with pair transverse momentum as well as centrality but not for -eccentricity, indicating a more asymmetric transverse emission of particle-pairs with higher transverse momentum in off-central collisions.

    nucl-thnucl-exEPJA(2022)·8 citations
  6. 06

    quadratures in angular-momentum projection

    Noritaka Shimizu · Yusuke Tsunoda

    While the angular-momentum projection is a common tool for theoretical nuclear structure studies, a large amount of computations are required particularly for triaxially deformed states. In the present work, we clarify the conditions of the exactness of quadratures in the projection method. For efficient computation, the Lebedev quadrature and spherical -design are introduced to the angular-momentum projection. The accuracy of the quadratures is discussed in comparison with the conventional Gauss-Legendre and trapezoidal quadratures. We found that the Lebedev quadrature is the most efficient among them and the necessary number of sampling points for the quadrature, which is often proportional to the computation time, is reduced by a factor 3/2 in comparison with the conventional method.

    nucl-thComput.Phys.Commun.(2023)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE