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Nuclear Theory·nucl-th

Wednesday·March 6, 2024

15 papers—10 primary·5 cross-listed

All15Primary10Cross-lists5
  1. 11

    Biquaternion representation of the spin one half and its application on the relativistic one electron atom

    Alejandro Arias Jiménez

    In this work we represent the Spin particles with complex quaternions using a transformation to 2x2 matrices in order to obtain the Pauli matrices. With this representation we determine the states, rotation operators and the total angular momentum function in the complex quaternion space. Using this representation we work the solution for the relativistic hydrogen atom.

    ↳ quant-phnucl-th0 citations
  2. 12

    Compact stars in Rastall gravity: hydrostatic equilibrium and radial pulsations

    Juan M. Z. Pretel🇧🇷 · Clésio E. Mota🇧🇷

    Within the context of Rastall gravity, we investigate the hydrostatic equilibrium and dynamical stability against radial pulsations of compact stars, where a free parameter measures the deviations from General Relativity (GR). We derive both the modified Tolman-Oppenheimer-Volkoff (TOV) equations and the Sturm-Liouville differential equation governing the adiabatic radial oscillations. Such equations are solved numerically in order to obtain the compact-star properties for two realistic equations of state (EoSs). For hadronic matter, the fundamental mode frequency becomes unstable almost at the critical central energy density corresponding to the maximum gravitational mass. However, for quark matter, where larger values of are required to observe appreciable changes in the mass-radius diagram, there exist stable stars after the maximum-mass configuration for negative values of . Using an independent analysis, our results reveal that the emergence of a cusp can be used as a criterion to indicate the onset of instability when the binding energy is plotted as a function of the proper mass. Specifically, we find that the central-density value where the binding energy is a minimum corresponds precisely to .

    ↳ gr-qcastro-ph.HEnucl-thGen.Rel.Grav.(2024)·25 citations
  3. 13

    Thermal effects on sound velocity peak and conformality in isospin QCD

    Ryuji Chiba🇯🇵 · Toru Kojo🇯🇵 · Daiki Suenaga🇯🇵

    We study thermal effects on equations of state (EOS) in isospin QCD, utilizing a quark-meson model coupled to a Polyakov loop. The quark-meson model is analyzed at one-loop that is the minimal order to include quark substructure constraints on pions which condense at finite isospin density. In the previous study we showed that the quark-meson model at zero temperature produces the sound velocity peak and the negative trace anomaly in the domain between the chiral effective theory regime at low density and the perturbative QCD regime at high density, in reasonable agreement with lattice simulations. We now include thermal effects from quarks in the Polyakov loop background and examine EOS, especially the sound velocity and trace anomaly along isentropic trajectories. At large isospin density, there are three temperature windows; (i) the pion condensed region with almost vanishing Polyakov loops, (ii) the pion condensed region with finite Polyakov loops, and (iii) the quark gas without pion condensates. In the domain (i), the gap associated with the pion condensate strongly quenches thermal excitations. As the system approaches the domain (ii), thermal quarks, which behave as non-relativistic particles, add energy density but little pressure, substantially reducing the sound velocity to the value less than the conformal value while increasing the trace anomaly toward the positive value. Approaching the domain (iii), thermal quarks become more relativistic as pion condensates melt, increasing sound velocity toward the conformal limit. Corrections from thermal pions are also briefly discussed.

    ↳ hep-phhep-latnucl-thPRD(2024)·15 citations
  4. 14

    A numerical algorithm for solving the coupled Schrödinger equations using inverse power method

    Jiaxing Zhao🇨🇳 · Shuzhe Shi🇨🇳

    The inverse power method is a numerical algorithm to obtain the eigenvectors of a matrix. In this work, we develop an iteration algorithm, based on the inverse power method, to numerically solve the Schrödinger equation that couples an arbitrary number of components. Such an algorithm can also be applied to the multi-body systems. To show the power and accuracy of this method, we also present an example of solving the Dirac equation under the presence of an external scalar potential and a constant magnetic field, with source code publicly available.

    ↳ physics.comp-phnucl-thquant-phComput.Phys.Commun.(2024)·2 citations
  5. 15

    Microscopic parametrization of the near threshold oscillations of the nucleon time-like effective electromagnetic form factors

    Francesco Rosini🇮🇹 · Simone Pacetti🇮🇹 · Olga Shekhovtsova🇮🇹 · Egle Tomasi-Gustafsson🇫🇷

    We present an analysis of the recent near threshold BESIII data for the nucleon time-like effective form factors. The damped oscillation emerging from the subtraction of the dipole formula is treated in non-perturbative-QCD, making use of the light cone distribution amplitudes expansion. Non-perturbative effects are accounted for by considering Q2-dependent coefficients in such expansions, whose free parameters are determined by fitting to the proton and neutron data. Possible implications and future analysis have been discussed.

    ↳ hep-phhep-exnucl-thEPJA(2024)·3 citations

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first authorsco-authorsvia INSPIRE