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Nuclear Theory·nucl-th

Thursday·April 6, 2023

5 papers—4 primary·1 cross-listed

All5Primary4Cross-lists1
  1. 01

    [Submitted on 5 Apr 2023]

    Exact spin polarization of massive and massless particles in relativistic fluids at global equilibrium

    Andrea Palermo🇮🇹 · Francesco Becattini🇮🇹

    We present the exact form of the spin polarization vector and the spin density matrix of massive and massless free particles of any spin and helicity at general global equilibrium in a relativistic fluid with non-vanishing thermal vorticity, thus extending the known expression at the linear order. The exact form is obtained by means of the analytic continuation of the relativistic density operator to imaginary thermal vorticity and the resummation of the obtained series. The phenomenological implications for the polarization of the hyperon in relativistic heavy-ion collisions are addressed.

    Comments:
    14 pages + 3 pages appendices. 2 figures. Figures have been corrected. Accepted for publication at EPJ+
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2304.02276 [pdf]
    Eur.Phys.J.Plus(2023)·24 citations
  2. 02

    [Submitted on 5 Apr 2023]

    A+2n compound nuclei and the unitary limit in nuclear physics

    P. E. Georgoudis🇫🇷

    This contribution discusses a new perception of the structure of compound nuclei by introducing intermediate states of the Feshbach formalism of nuclear reactions in the Interacting Boson Model of nuclear structure. The stake is to explore the manifestation of the unitary limit in heavy, even-even nuclei. Interactions that govern Feshbach resonances of cold and dilute atomic gases suggest the formulation of an IBM-compound Hamiltonian for scattering two neutrons (2n) from a heavy, even-even target (A). The solutions of the corresponding coupled channel equations host a 2n-IBM state resonance. It turns out that the unitary limit is measurable in a heavy A+2n compound nucleus at low temperatures. That measurement is feasible through the fluctuations of the cross-sections that tune the 2n-A scattering length.

    Comments:
    Contribution to 13th International Spring Seminar on Nuclear Physics Perspectives and Challenges in Nuclear Structure after 70 Years of Shell Model (ISS 2022) 14/05/2022 - 20/05/2022 Sant'Angelo, Italy
    Subjects:
    Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2304.02400 [pdf]
    J.Phys.Conf.Ser.(2023)·1 citation
  3. 03

    [Submitted on 5 Apr 2023]

    Unstable Anisotropic Neutron Stars: Probing the Limits of Gravitational Collapse

    S. R. Mohanty🇮🇳 · Sayantan Ghosh🇮🇳 · Bharat Kumar🇮🇳

    Neutron stars (NSs) are incredibly versatile for studying various important aspects of high-energy and compact-object physics. These celestial objects contain extreme matter at incredibly high densities in their interiors, leading to the risk of instabilities that may cause them to collapse into a black hole (BH). This paper focuses on exploring the stability and gravitational collapse of NSs. For a more realistic approach we have considered the pressure to be locally anisotropic. We utilize the BL-Model to describe the anisotropy inside the NS. The presence of quarks in the core of an NS can heavily affect its stability. Hence, along with pure hadronic EOSs, we have also considered Hadron-Quark phase transition (HQPT) EOSs for this paper's analysis. We subject the anisotropic NSs to radial perturbations to study their stability against radial oscillations. NSs exhibiting imaginary eigen-frequencies are identified as unstable, and their inevitable destiny is gravitational collapse, resulting in the formation of a BH. We consider the interior of these unstable anisotropic NSs to be a non-ideal fluid in a non-adiabatic background in order to study its dynamical evolution during the collapse. We examine the temporal evolution of key properties of NSs, such as mass, density, heat flux, and anisotropy during the process of gravitational collapse. We present an innovative and viable approach to detect such high-energy gravitational collapse events, providing valuable insights into the properties of the static NS before its collapse.

    Comments:
    Accepted in PRD
    Subjects:
    Nuclear Theory (nucl-th); General Relativity and Quantum Cosmology (gr-qc)
    arXiv:
    2304.02439 [pdf]
    PRD(2024)·18 citations
  4. 04

    [Submitted on 5 Apr 2023]

    Temperature and Strong Magnetic Field Effects in Dense Matter

    J. Peterson🇺🇸 · P. Costa🇵🇹 · R. Kumar🇺🇸 · V. Dexheimer🇺🇸 · R. Negreiros🇧🇷 · C. Providencia🇵🇹

    We study consistently the effects of magnetic field on hot and dense matter. In particular, we look for differences that arise due to assumptions that reproduce the conditions produced in particle collisions or astrophysical scenarios, such as in the core of fully evolved neutron stars (beyond the protoneutron star stage). We assume the magnetic field to be either constant or follow a profile extracted from general relativity calculations of magnetars and make use of two realistic models that can consistently describe chiral symmetry restoration and deconfinement to quark matter, the Chiral Mean Field (CMF) and the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) models. We find that net isospin, net strangeness, and weak chemical equilibrium with leptons can considerably change the effects of temperature and magnetic fields on particle content and deconfinement in dense matter. We finish by discussing the possibility of experimentally detecting quark deconfinement in dense and/or hot matter and the possible role played by magnetic fields.

    Comments:
    Published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2304.02454 [pdf]
    PRD(2023)·21 citations
  5. 05

    [Submitted on 4 Apr 2023] (cross-list from hep-ph)

    Spin-Dependent Interactions and Heavy-Quark Transport in the QGP

    Zhanduo Tang🇺🇸 · Ralf Rapp🇺🇸

    We extend a previously constructed T-matrix approach to the quark-gluon plasma (QGP) to include the effects of spin-dependent interactions between partons. Following earlier work within the relativistic quark model, the spin-dependent interactions figure as relativistic corrections to the Cornell potential. When applied to the vacuum spectroscopy of quarkonia, in particular their mass splittings in S- and P-wave states, the issue of the Lorentz structure of the confining potential arises. We confirm that a significant admixture of a vector interaction (to the previously assumed scalar interaction) improves the description of the experimental mass splittings. The temperature corrections to the in-medium potential are constrained by results from thermal lattice-QCD for the equation of state (EoS) and heavy-quark (HQ) free energy in a selfconsistent set-up for heavy- and light-parton spectral functions in the QGP. We then deploy the refined in-medium heavy-light T-matrix to compute the charm-quark transport coefficients in the QGP. The vector component of the confining potential, through its relativistic corrections, enhances the friction coefficient for charm quarks in the QGP over previous calculations by tens of percent at low momenta and temperatures, and more at higher momenta. Our results are promising for improving the current phenomenology of open heavy-flavor observables at Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).

    Comments:
    17 pages, 11 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2304.02060 [pdf]
    PRC(2023)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE