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Nuclear Theory·nucl-th

Thursday·July 9, 2020

12 papers—5 primary·7 cross-listed

All12Primary5Cross-lists7
  1. 01

    GW190814: Impact of a 2.6 solar mass neutron star on nucleonic equations of state

    F.J. Fattoyev · C.J. Horowitz · J. Piekarewicz · Brendan Reed

    Is the secondary component of GW190814 the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system [R. Abbott et al., ApJ Lett., 896, L44 (2020)]? This is the central question animating this letter. Covariant density functional theory provides a unique framework to investigate both the properties of finite nuclei and neutron stars, while enforcing causality at all densities. By tuning existing energy density functionals we were able to: (a) account for a 2.6 Msun neutron star, (b) satisfy the original constraint on the tidal deformability of a 1.4 Msun neutron star, and (c) reproduce ground-state properties of finite nuclei. Yet, for the class of models explored in this work, we find that the stiffening of the equation of state required to support super-massive neutron stars is inconsistent with either constraints obtained from energetic heavy-ion collisions or from the low deformability of medium-mass stars. Thus, we speculate that the maximum neutron star mass can not be significantly higher than the existing observational limit and that the 2.6 Msun compact object is likely to be the lightest black hole ever discovered.

    nucl-thastro-ph.HEnucl-exPRC(2020)·236 citations
  2. 02

    Particle polarization, spin tensor and the Wigner distribution in relativistic systems

    Leonardo Tinti🇩🇪 · Wojciech Florkowski🇵🇱

    Particle spin polarization is known to be linked both to rotation (angular momentum) and magnetization of a many particle system. However, in the most common formulation of relativistic kinetic theory, the spin degrees of freedom appear only as degeneracy factors multiplying phase-space distributions. Thus, it is important to develop theoretical tools that allow to make predictions regarding the spin polarization of particles, which can be directly confronted with experimental data. Herein, we discuss a link between the relativistic spin tensor and particle spin polarization, and elucidate the connections between the Wigner function and average polarization. Our results may be useful for theoretical interpretation of heavy-ion data on spin polarization of the produced hadrons.

    nucl-thhep-th17 citations
  3. 03

    A unified view of the first-excited and states of Cd, Sn and Te isotopes

    Bhoomika Maheshwari

    Symmetries are known to play an important role in the low lying level structure of Sn isotopes, mostly in terms of the seniority and generalized seniority schemes. In this paper, we revisit the multi-j generalized seniority approach for the first excited and states in the Cd (), Sn () and Te () isotopes, where the Cd and Te isotopes represent two-proton hole and two-proton particle nuclei, thus involving both kind of particles (protons and neutrons) in contrast to Sn isotopes. Interestingly, the approach based on neutron valence space alone is able to explain the B(E2) and B(E3) trends respectively for the and states in all the three Cd, Sn and Te isotopes. The new results on the inverted parabolic behavior of B(E3) values in Cd and Te isotopes are understood in a manner identical to that of Sn isotopes by using the generalized seniority scheme. No shell quenching is supported by these calculations; hence, the neutron magic numbers, and , remain robust in these isotopic chains. It is quite surprising that the generalized seniority continues to be reasonably successful away from the semi-magic region, thus providing a unifying view of the and states.

    nucl-thEur.Phys.J.ST(2020)·5 citations
  4. 04

    Unitary ambiguity of NN contact interactions and the 3N force

    L. Girlanda🇮🇹 · A. Kievsky🇮🇹 · L. E. Marcucci🇮🇹 · M. Viviani🇮🇹

    We identify a redundancy between two- and three-nucleon contact interactions at the fourth and fifth order of the chiral expansion respectively. In particular we show that tensor-type and spin-orbit three-nucleon contact interactions effectively account for that part of the two-nucleon interaction which depends on the total center-of-mass momentum and is unconstrained by relativity. This might give the chiral effective field theory enough flexibility to successfully address scattering observables already at N3LO.

    nucl-thPRC(2020)·21 citations
  5. 05

    Pion interferometry at 200 GeV using anisotropic hydrodynamics

    Mubarak Alqahtani🇸🇦 · Michael Strickland🇺🇸

    In this paper, we continue our phenomenological studies of heavy-ion collisions using 3+1d anisotropic hydrodynamics (aHydro). In previous works, we compared quasiparticle aHydro (aHydroQP) with ALICE 2.76 TeV Pb-Pb and RHIC 200 GeV Au-Au collision results. At both energies, the agreement was quite good between aHydroQP and the experimental data for many observables. In this work, we present comparisons of the Hanbury Brown--Twiss (HBT) radii and their ratios determined using pi+ pi+ pairs produced in 200 GeV Au-Au collisions. We first present comparisons with STAR results for the HBT radii and their ratios. We then present comparisons with PHENIX results for the HBT radii and their ratios. In both cases, we find reasonable agreement between aHydroQP predictions and available experimental results for the ratios of HBT radii. At the level of the radii themselves, in some cases quantitative differences on the order of 10-20% remain, which deserve further study.

    nucl-thhep-phPRC(2020)·15 citations

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