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Nuclear Theory·nucl-th

Friday·October 22, 2021

16 papers—7 primary·9 cross-listed

All16Primary7Cross-lists9
  1. 01

    [Submitted on 20 Oct 2021]

    Two-Fermion Bound and Scattering States in a Finite Volume including QED in P-Wave and Beyond

    Gianluca Stellin🇩🇪

    Introducing a short range force coupling the spinless fermions to one unit of angular momentum in the framework of pionless EFT, we first report the two-body scattering amplitudes with Coulomb corrections, extended to two fermions of opposite charge in refs. [1,2]. Motivated by the growing interest in lattice approaches, we immerse the system into a cubic box with periodic boundary conditions and display the finite-volume corrections to the energy of the lowest bound and unbound eigenstates. The latter turn out to consist of power law terms proportional to the fine-structure constant. In the calculations, quadratic and higher order contributions in are discarded, on the grounds that the gapped nature of the momentum operator in the finite-volume environment allows for a perturbative treatment of the QED interactions. An outlook on the extension of the analysis to D-wave short-range interactions is eventually given.

    Comments:
    11 pages, 1 fugure, proceedings for the 38th International Symposium on Lattice Field Theory (Lattice2021), 26-30 July 2021, Zoom/Gather@MIT (Cambridge, USA). arXiv admin note: text overlap with arXiv:2008.06553
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
    arXiv:
    2110.10485 [pdf]
    PoS(2022)·0 citations
  2. 02

    [Submitted on 21 Oct 2021]

    Coupled-channel description for mirror mass-11 nuclei compared to shell-model structures

    K. Amos · S. Karataglidis · L. Canton · P. R. Fraser · K. Murulane

    The spectra of mass-11 nuclei are unusual, and so pose a challenge for theoretical models of their structure. The set of isobars range from being well bound to nucleon emission (11B,11C) through weakly bound (11Li, 11Be), with the former taking the form of a two neutron halo, to being proton unstable (11N,11O). A self-consistent approach to understand this set of nuclei is especially important as the mirror pair 11Be-11N exhibit a parity-inverted ground state compared to their neighbouring nuclei. Herein the Multi-Channel Algebraic Scattering (MCAS) method has been used to describe the low excitation spectra of those isobars in terms of nucleon-nucleus clusters. A collective model description of the low-excitation states of the mass-10 core nuclei has been used to form the coupled-channel interactions required in the method. For comparison, and to understand the underlying configurations, a shell model approach has been used to obtain those spectra with no-core (0+2+4)hw and (0+2)hw shell-model spaces for the mass 10 and mass 11 nuclei respectively.The results of the calculations suggest the need of a strong coupling in the collective coupled-channel vibrational model. In particular, the strong coupling of the collective 2+_1 state of 10Be to the valence neutron plays a decisive role in forming the positive parity ground state in11Be.

    Comments:
    23 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2110.10985 [pdf]
    EPJA(2022)·1 citation
  3. 03

    [Submitted on 21 Oct 2021]

    Five-body resonances in He and C using the complex scaling method

    Takayuki Myo · Myagmarjav Odsuren · Kiyoshi Katō

    We study many-body resonances in the neuron-rich He and the mirror proton-rich C using the He++++ five-body model with the isospin system. Resonances are described with the complex energy eigenvalues as the Gamow states using the complex scaling method. In He, we obtain five states, in which four states are resonances, and in C all five states are resonances.We discuss the isospin-symmetry breaking dynamically induced by the Coulomb interaction in the energy spectra and decay widths of the resonances in two mirror nuclei. We predict the resonance energies and decay widths for the future experiments. We also investigate the configurations of valence nucleons above He in two nuclei with the coupling scheme and all the states dominantly have the -shell configurations. From the configuration mixing, He and C give the similar results, which indicates the good symmetry in two nuclei.

    Comments:
    7 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2110.11041 [pdf]
    PRC(2021)·17 citations
  4. 04

    [Submitted on 21 Oct 2021]

    Reconciling multi-messenger constraints with chiral symmetry restoration

    Michał Marczenko🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    We analyze the recent astrophysical constraints in the context of a hadronic equation of state (EoS), in which the baryonic matter is subject to chiral symmetry restoration. We show that with such EoS it is possible to reconcile the modern constraints on the neutron star (NS) mass, radius, and tidal deformability (TD). We find that the softening of the EoS, required by the TD constraint of a canonical NS, followed by a subsequent stiffening, required by the constraint, is driven by the appearance of matter due to partial restoration of chiral symmetry. Consequently, a purely hadronic EoS that accounts for the fundamental properties of quantum chromodynamics linked to the dynamical emergence of parity doubling with degenerate masses of nucleons and resonances can be fully consistent with multi-messenger data. Therefore, with the present constraints on the EoS, the conclusion about the existence of the quark matter in the stellar core may still be premature.

    Comments:
    version accepted for publication ApJ Letters
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2110.11056 [pdf]
    ApJL(2022)·26 citations
  5. 05

    [Submitted on 15 Oct 2021]

    Probing dense matter physics with transiently-accreting neutron stars: the case of source MXB 1659-29

    Melissa Mendes · Farrukh J. Fattoyev · Andrew Cumming · Charles Gale

    Recent observational data on transiently-accreting neutron stars has unequivocally shown fast-cooling sources, such as in the case of neutron star MXB 1659-29. Previous calculations have estimated its total neutrino luminosity and heat capacity, as well as suggested that direct Urca reactions take place in of the volume of the core. In this paper, we reproduce the inferred luminosity of this source with detailed models of equations of state (EOS) and nuclear pairing gaps. We show that three superfluidity gap models are inconsistent with data for all EOS and another three are disfavoured because of fine tuning arguments. We also calculate the total heat capacity for all constructed stars and show that independent observations of mass and luminosity could set constraints on the core superfluidity of a source as well as the density slope of the symmetry energy, L. This is an important step towards defining a universal equation of state for neutron stars and therefore, towards a better understanding of the phase diagram of asymmetric matter at high densities.

    Comments:
    Talk given at the XVI Marcel Grossmann Meeting (2021), to be published on their proceedings
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
    arXiv:
    2110.11077 [pdf]
    2 citations
  6. 06

    [Submitted on 21 Oct 2021]

    The complete inverse Kohn-Sham problem: from the density to the energy

    A. Liardi · F. Marino · G. Colò · X. Roca-Maza · E. Vigezzi

    A complete solution to the inverse problem of Kohn-Sham (KS) density functional theory is proposed. Our method consists of two steps. First, the effective KS potential is determined from the ground state density of a given system. Then, the knowledge of the potentials along a path in the space of densities is exploited in a line integration formula to determine numerically the KS energy of that system. A possible choice for the density path is proposed. A benchmark in the case of a simplified yet realistic nuclear system is shown to be successful, so that the method seems promising for future applications.

    Subjects:
    Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el)
    arXiv:
    2110.11193 [pdf]
    PRC(2022)·2 citations
  7. 07

    [Submitted on 21 Oct 2021]

    Nuclear medium effects in neutrino- and antineutrino-nucleus scattering

    Natalie Jachowicz🇧🇪 · Alexis Nikolakopoulos🇨🇭

    In this paper we study the influence of nuclear medium effects on quasi-elastic neutrino-nucleus scattering processes. We focus on effects provided by the nuclear mean field and random phase correlations and pay special attention to differences between neutrino- and antineutrino-induced reactions. We confront our results with the T2K and MiniBooNE data for both neutrinos and antineutrinos and the neutrino-antineutrino asymmetry. In view of the recently published ab initio results we provide a careful comparison between our cross section predictions and the ab-initio calculations.

    Comments:
    Accepted to Eur. Phys. J. Spec. Top. : Neutrino Interactions in the Intermediate and High Energy Region
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2110.11321 [pdf]
    Eur.Phys.J.ST(2021)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE