PaperPanorama

Nuclear Theory·nucl-th

Thursday·May 17, 2018

9 papers7 primary·2 cross-listed

  1. 08

    [Submitted on 15 May 2018] (cross-list from astro-ph.HE)

    Transport coefficients of leptons in superconducting neutron star cores

    Peter Shternin🇷🇺

    I consider the thermal conductivity and shear viscosity of leptons (electrons and muons) in the nucleon NS cores where protons are in the superconducting state. I restrict the consideration to the case of not too high temperatures , where is the critical temperature of the proton pairing. In this case, lepton collisions with protons can be neglected. Charged lepton collision frequencies are mainly determined by the transverse plasmon exchange and are mediated by the character of the transverse plasma screening. In our previous works [Shternin \& Yakovlev, Phys. Rev. D {\bf 75} 103004 (2007); {\bf 78} 063006 (2008)] the superconducting proton contribution to the transverse screening was considered in the Pippard limit , where is the proton pairing gap, is the proton Fermi velocity, and is the typical transferred momentum in collisions. However, for large critical temperatures (large ) and relatively small densities (small ) the Pippard limit may become invalid. In the present study I show that this is indeed the case and that the older calculations severely underestimated the screening in a certain range of the parameters appropriate to the neutron star cores. As a consequence, the kinetic coefficients at are found to be smaller than in previous calculations.

    Comments:
    18 pages, 11 figures, accepted for publication in PRD. In v.2 new figure 9 is added and BSK21 results are corrected
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1805.06000 [pdf]
    PRD(2018)·16 citations
  2. 09

    [Submitted on 16 May 2018] (cross-list from hep-ph)

    Spectroscopy of the hidden-charm and tetraquarks

    Muhammad Naeem Anwar🇨🇳 · Jacopo Ferretti🇨🇳 · Elena Santopinto🇮🇹

    We calculate the spectrum of and tetraquarks, where , and stand for light (), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a () tetraquark configuration is made up of a heavy-light diquark, (), and anti-diquark, (). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm () and hidden-charm hidden-strange () sectors.

    Comments:
    Discussions extended, references added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1805.06276 [pdf]
    PRD(2018)·78 citations

Affiliations

first authorsco-authorsvia INSPIRE