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Nuclear Theory·nucl-th

Friday·January 15, 2021

6 papers—4 primary·2 cross-listed

All6Primary4Cross-lists2
  1. 01

    [Submitted on 14 Jan 2021]

    Symmetry energy effect on the secondary component of GW190814 as a neutron star

    Xuhao Wu🇨🇳 · Shishao Bao🇨🇳 · Hong Shen🇨🇳 · Renxin Xu🇨🇳

    The secondary component of GW190814 with a mass of 2.50-2.67 may be the lightest black hole or the heaviest neutron star ever observed in a binary compact object system. To explore the possible equation of state (EOS), which can support such massive neutron star, we apply the relativistic mean-field model with a density-dependent isovector coupling constant to describe the neutron-star matter. The acceptable EOS should satisfy some constraints: the EOS model can provide a satisfactory description of the nuclei; the maximum mass is above 2.6 ; the tidal deformability of a canonical 1.4 neutron star should lie in the constrained range from GW170817. In this paper, we find that the nuclear symmetry energy and its density dependence play a crucial role in determining the EOS of neutron-star matter. The constraints from the mass of 2.6 and the tidal deformability (based on the assumption that GW190814 is a neutron star-black hole binary) can be satisfied as the slope of symmetry energy MeV. Even including the constraint of from GW170817 which suppresses the EOS stiffness at low density, the possibility that the secondary component of GW190814 is a massive neutron star cannot be excluded in this study.

    Comments:
    8 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2101.05476 [pdf]
    PRC(2021)·25 citations
  2. 02

    [Submitted on 14 Jan 2021]

    Transfer reactions between odd-odd and even-even nuclei by using IBFFM

    Ruslan Magaña Vsevolodovna · Elena Santopinto · Roelof Bijker

    Spectroscopic Amplitudes (SA) in the Interacting Boson Fermion Fermion Model (IBFFM) are necessary for the computation of decays but also for cross sections of heavy-ion reactions, in particular, Double Charge Exchange reactions for the NUMEN collaboration, if one does not want to use the closure limit. We present for the first time: i) the formalism and operators to compute in a general case the spectroscopic amplitudes in the scheme IBFFM from an even-even to odd-odd nuclei, in a way suited to be used in reaction code, i.e., extracting the contribution of each orbital; 2) the odd-odd nuclei as described by the old IBFFM are obtained for the first time with the new implementation of Machine Learning (ML) techniques for fitting the parameters, getting a more realistic description. The one body transition densities for Cd In and In Sn are part of the experimental program of the NUMEN experiment, which aims to find constraints on Neutrinoless double beta decay matrix elements.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2101.05659 [pdf]
    PRC(2022)·8 citations
  3. 03

    [Submitted on 14 Jan 2021]

    Properties of the QGP created in heavy-ion collisions

    P. Moreau🇺🇸 · O. Soloveva🇩🇪 · I. Grishmanovskii🇩🇪 · V. Voronyuk🇷🇺 · L. Oliva🇩🇪 · T. Song🇩🇪 · V. Kireyeu🇷🇺 · G. Coci🇩🇪 · E. Bratkovskaya🇩🇪

    We review the properties of the strongly interacting quark-gluon plasma (QGP) at finite temperature and baryon chemical potential as created in heavy-ion collisions at ultrarelativistic energies. The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature from lattice QCD. Based on a microscopic transport description of heavy-ion collisions we discuss which observables are sensitive to the QGP creation and its properties.

    Comments:
    10 pages, 8 figures, contribution to the special volume of IWARA-2020 (9th International Workshop on Astronomy and Relativistic Astrophysics) of Astronomische Nachrichten. arXiv admin note: substantial text overlap with arXiv:2005.07028
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2101.05688 [pdf]
    Astron.Nachr.(2021)·15 citations
  4. 04

    [Submitted on 14 Jan 2021]

    Hadron yields in central nucleus-nucleus collisions, the statistical hadronization model and the QCD phase diagram

    A. Andronic🇩🇪 · P. Braun-Munzinger🇩🇪 · K. Redlich🇵🇱 · J. Stachel🇩🇪

    The description of hadron production in relativistic heavy-ion collisions in the statistical hadronization model is very good, over a broad range of collision energy. We outline this both for the light (u, d, s) and heavy (charm) quarks and discuss the connection it brings to the phase diagram of QCD.

    Comments:
    12 pages, 4 figures; proceedings of the workshop "Criticality in QCD and the Hadron Resonance Gas", Wroclaw (online), 29-31.07.2020
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2101.05747 [pdf]
    Acta Phys.Polon.Supp.(2021)·14 citations
  5. 05

    [Submitted on 13 Jan 2021] (cross-list from hep-ph)

    Magnetars and Axion-like Particles: Probes with the Hard X-ray Spectrum

    Jean-François Fortin🇨🇦 · Huai-Ke Guo🇺🇸 · Steven P. Harris🇺🇸 · Elijah Sheridan🇺🇸 · Kuver Sinha🇺🇸

    Quiescent hard X-ray and soft gamma-ray emission from neutron stars constitute a promising frontier to explore axion-like-particles (ALPs). ALP production in the core peaks at energies of a few keV to a few hundreds of keV; subsequently, the ALPs escape and convert to photons in the magnetosphere. The emissivity goes as while the conversion probability is enhanced for large magnetic fields, making magnetars, with their high core temperatures and strong magnetic fields, ideal targets for probing ALPs. We compute the energy spectrum of photons resulting from conversion of ALPs in the magnetosphere and then compare it against hard X-ray data from NuSTAR, INTEGRAL, and XMM-Newton, for a set of eight magnetars for which such data exists. Upper limits are placed on the product of the ALP-nucleon and ALP-photon couplings. For the production in the core, we perform a calculation of the ALP emissivity in degenerate nuclear matter modeled by a relativistic mean field theory. The reduction of the emissivity due to improvements to the one-pion exchange approximation is incorporated, as is the suppression of the emissivity due to proton superfluidity in the neutron star core. A range of core temperatures is considered, corresponding to different models of the steady heat transfer from the core to the stellar surface. For the subsequent conversion, we solve the coupled differential equations mixing ALPs and photons in the magnetosphere. The conversion occurs due to a competition between the dipolar magnetic field and the photon refractive index induced by the external magnetic field. Semi-analytic expressions are provided alongside the full numerical results. We also present an analysis of the uncertainty on the axion limits we derive due to the uncertainties in the magnetar masses, nuclear matter equation of state, and the proton superfluid critical temperature.

    Comments:
    v1: 44 pages, 15 figures. Comments welcome v2: Updated version with uncertainty bands on ALP couplings coming from different choices of the nuclear equation of state, the mass of the magnetar, and the model of proton singlet superfluidity. Calculation of n+p-->n+p+a clarified. Version matches that published in JCAP
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2101.05302 [pdf]
    JCAP(2021)·41 citations
  6. 06

    [Submitted on 11 Jan 2021] (cross-list from physics.data-an)

    Multivariate cumulants in flow analyses: The Next Generation

    Ante Bilandzic🇩🇪 · Marcel Lesch🇩🇪 · Cindy Mordasini🇩🇪 · Seyed Farid Taghavi🇩🇪

    We reconcile for the first time the strict mathematical formalism of multivariate cumulants with the usage of cumulants in anisotropic flow analyses in high-energy nuclear collisions. This reconciliation yields to the next generation of estimators to be used in flow analyses. We review all fundamental properties of multivariate cumulants and use them as a foundation to establish two simple necessary conditions to determine whether some multivariate random variable is a multivariate cumulant in the basis they are expressed in. We argue that properties of cumulants are preserved only for the stochastic variables on which the cumulant expansion has been performed directly, and if there are no underlying symmetries due to which some terms in the cumulant expansion are identically zero. We illustrate one possibility of new multivariate cumulants of azimuthal angles by defining them event-by-event and by keeping all non-isotropic terms in the cumulant expansion. Further, we introduce new cumulants of flow amplitudes named Asymmetric Cumulants, which generalize recently introduced Symmetric Cumulants for the case when flow amplitudes are raised to different powers. Finally, we present the new concept of Cumulants of Symmetry Plane Correlations and provide the first realisation for the lowest orders. The new estimators can be used directly to constrain the multivariate probability density function of flow fluctuations, since its functional form can be reconstructed only from its true moments or cumulants. The new definition for cumulants of azimuthal angles enables separation of nonflow and flow contributions, and offers first insights into how the combinatorial background contributes for small multiplicities to flow measurements with correlation techniques. All the presented results are supported by Monte Carlo studies using state-of-the-art models.

    Comments:
    32 pages, 9 figures. Version accepted for publication in PRC
    Subjects:
    Data Analysis, Statistics and Probability (physics.data-an); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
    arXiv:
    2101.05619 [pdf]
    PRC(2022)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE