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Nuclear Theory·nucl-th

Thursday·February 18, 2016

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 16 Feb 2016]

    Di-neutrons in neutron matter within Brueckner-Hartree-Fock approach

    F. Isaule · H. F. Arellano · A. Rios

    We investigate the appearance of di-neutron bound states in pure neutron matter within the Brueckner-Hartree-Fock approach at zero temperature. We consider Argonne and Paris bare interactions as well as chiral two- and three-nucleon forces. Self-consistent single-particle potentials are calculated controlling explicitly singularities in the matrix associated with bound states. Di-neutrons are loosely bound, with binding energies below MeV, but are unambiguously present for Fermi momenta below fm for all interactions. Within the same framework we are able to calculate and characterize di-neutron bound states, obtaining mean radii as high as fm. The resulting equations of state and mass-radius relations for pure neutron stars are analyzed including di-neutron contributions.

    Comments:
    26 pages, 9 figures, 2 tables. Accepted abridged version in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.05234 [pdf]
    PRC(2016)·27 citations
  2. 02

    [Submitted on 17 Feb 2016]

    Microscopic study of Ca+Ni fusion reactions

    D. Bourgin🇫🇷 · C. Simenel🇦🇺 · S. Courtin🇫🇷 · F. Haas🇫🇷

    Background: Heavy-ion fusion reactions at energies near the Coulomb barrier are influenced by couplings between the relative motion and nuclear intrinsic degrees of freedom of the colliding nuclei. The time-dependent Hartree-Fock (TDHF) theory, incorporating the couplings at the mean-field level, as well as the coupled-channels (CC) method are standard approaches to describe low energy nuclear reactions. Purpose: To investigate the effect of couplings to inelastic and transfer channels on the fusion cross sections for the reactions Ca+Ni and Ca+Ni. Methods: Fusion cross sections around and below the Coulomb barrier have been obtained from coupled-channels (CC) calculations, using the bare nucleus-nucleus potential calculated with the frozen Hartree-Fock method and coupling parameters taken from known nuclear structure data. The fusion thresholds and neutron transfer probabilities have been calculated with the TDHF method. Results: For Ca+Ni, the TDHF fusion threshold is in agreement with the most probable barrier obtained in the CC calculations including the couplings to the low-lying octupole state for Ca and to the low-lying quadrupole state for Ni. This indicates that the octupole and quadrupole states are the dominant excitations while neutron transfer is shown to be weak. For Ca+Ni, the TDHF barrier is lower than predicted by the CC calculations including the same inelastic couplings as those for Ca+Ni. TDHF calculations show large neutron transfer probabilities in Ca+Ni which could result in a lowering of the fusion threshold. Conclusions: Inelastic channels play an important role in Ca+Ni and Ca+Ni reactions. The role of neutron transfer channels has been highlighted in Ca+Ni.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.05389 [pdf]
    PRC(2016)·24 citations
  3. 03

    [Submitted on 17 Feb 2016]

    Weak and strong coupling limits of the Boltzmann equation in the relaxation-time approximation

    Amaresh Jaiswal🇩🇪 · Bengt Friman🇩🇪 · Krzysztof Redlich🇵🇱

    We consider a momentum dependent relaxation time for the Boltzmann equation in the relaxation time approximation. We employ a power law parametrization for the momentum dependence of the relaxation time, and calculate the shear and bulk viscosity, as well as, the charge and heat conductivity. We show, that for the two popular parametrizations, referred to as the linear and quadratic ansatz, one can obtain transport coefficients which corresponds to the weak and strong coupling regimes, respectively. We also show that, for a system of massless particles with vanishing chemical potential, the off-equilibrium corrections to the phase-space distribution function calculated with the quadratic ansatz are identical with those of the Grad's 14-moment method.

    Comments:
    6 pages
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1602.05424 [pdf]
    11 citations
  4. 04

    [Submitted on 17 Feb 2016]

    Investigating the QCD phase diagram with hadron multiplicities at NICA

    F. Becattini (U. Florence, Italy)🇮🇹 · R. Stock (U. Franfkurt, Germany)🇩🇪

    We discuss the potential of the experimental programme at NICA to investigate the QCD phase diagram and particularly the position of the critical line at large baryon-chemical potential with accurate measurements of particle multiplicities. We briefly review the present status and we outline the tasks to be accomplished both theoretically and the experimentally to make hadronic abundances a sensitive probe.

    Comments:
    4 pages, 1 figure, to appear in the EPJA Topical Issue on "The NICA White Paper"
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.05482 [pdf]
    EPJA(2016)·3 citations
  5. 05

    [Submitted on 16 Feb 2016] (cross-list from hep-ph)

    Long Range Azimuthal Correlations of Multiple Gluons in Gluon Saturation Limit

    Sener Ozonder🇺🇸

    We calculate the inclusive gluon correlation function for arbitrary number of gluons with full rapidity and transverse momentum dependence for the initial glasma state of the p-p, p-A and A-A collisions. The formula we derive via superdiagrams generates cumulants for any number of gluons. Higher order cumulants contain information on correlations between multiple gluons, and they are necessary for calculations of higher dimensional ridges as well as flow coefficients from multi-particle correlations.

    Comments:
    12 pages, 3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1602.04888 [pdf]
    PRD(2016)·6 citations
  6. 06

    [Submitted on 15 Feb 2016] (cross-list from astro-ph.SR)

    Strong screening effects on resonant nuclear reaction Mg Al in the surface of magnetars

    Jing-Jing Liu

    Based on the theory of relativistic superstrong magnetic fields(SMFs), by using the method of the Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening(SES) in SMFs, and the influence of SES on the nuclear reaction of Mg Al. Our calculations show that the nuclear reaction will be markedly effected by the SES in SMFs in the surface of magnetars. Our calculated screening rates can increase two orders of magnitude due to SES in SMFs.

    Subjects:
    Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1602.05501 [pdf]
    Res.Astron.Astrophys.(2016)·16 citations
  7. 07

    [Submitted on 17 Feb 2016] (cross-list from hep-ph)

    Present Status of Single Pion Production in Neutrino-Nucleus Reactions

    L. Alvarez-Ruso🇪🇸 · E. Hernandez🇪🇸 · J. Nieves🇪🇸 · M. J. Vicente Vacas🇪🇸

    Some of the recent progress in the physics of pion production induced by neutrinos on nucleons and nuclei is reviewed from a theoretical perspective. The importance of Watson's theorem to reconcile ANL and BNL data with the off-diagonal Goldberger-Treiman relation for the is discussed. The disagreement between MiniBooNE data and theoretical calculations is presented in the light of the new MINERvA data. The coherent pion production data on C obtained by MINERvA are also compared to different microscopic and PCAC models.

    Comments:
    8 pages, 4 figures, prepared for the Proceedings of the 10th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt15)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1602.05562 [pdf]
    JPS Conf.Proc.(2016)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE