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Nuclear Theory·nucl-th

Thursday·September 24, 2015

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 04

    [Submitted on 23 Sept 2015] (cross-list from hep-th)

    Glueball-baryon interactions in holographic QCD

    Si-wen Li🇨🇳

    Studying the Witten-Sakai-Sugimoto model with type IIA string theory, we find the glueball-baryon interaction is predicted in this model. The glueball is identified as the 11D gravitational waves or graviton described by the M5-brane supergravity solution. Employing the relation of M-theory and type IIA string theory, glueball is also 10D gravitational perturbations which are the excited modes by close strings in the bulk of this model. On the other hand, baryon is identified as a D4-brane wrapped on which is named as baryon vertex, so the glueball-baryon interaction is nothing but the close string/baryon vertex interaction in this model. Since the baryon vertex could be equivalently treated as the instanton configurations on the flavor brane, we identify the glueball-baryon interaction as "graviton-instanton" interaction in order to describe it quantitatively by the quantum mechanical system for the collective modes of baryons. So the effective Hamiltonian can be obtained by considering the gravitational perturbations in the flavor brane action. With this Hamiltonian, the amplitudes and the selection rules of the glueball-baryon interaction can be analytically calculated in the strong coupling limit. We show our calculations explicitly in two characteristic situations which are "scalar and tensor glueball interacting with baryons". Although there is a long way to go, our work provides a holographic way to understand the interactions of baryons in hadronic physics and nuclear physics by the underlying string theory.

    Comments:
    16 pages, adding the Appendix C and transition amplitude in this version
    Subjects:
    High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1509.06914 [pdf]
    PLB(2017)·12 citations
  2. 05

    [Submitted on 23 Sept 2015] (cross-list from hep-ph)

    Magnetically induced QCD Kondo effect

    Sho Ozaki🇯🇵 · Kazunori Itakura🇯🇵 · Yoshio Kuramoto🇯🇵

    The "QCD Kondo effect" stems from the color exchange interaction in QCD with non-Abelian property, and can be realized in a high-density quark matter containing heavy-quark impurities. We propose a novel type of the QCD Kondo effect induced by a strong magnetic field. In addition to the fact that the magnetic field does not affect the color degrees of freedom, two properties caused by the Landau quantization in a strong magnetic field are essential for the "magnetically induced QCD Kondo effect"; (1) dimensional reduction to 1+1-dimensions, and (2) finiteness of the density of states for lowest energy quarks. We demonstrate that, in a strong magnetic field , the scattering amplitude of a massless quark off a heavy quark impurity indeed shows a characteristic behavior of the Kondo effect. The resulting Kondo scale is estimated as where and are the fine structure constant of strong interaction and the number of colors in QCD, and is the electric charge of light quarks.

    Comments:
    34 pages, 6 figures, version published in PRD
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1509.06966 [pdf]
    PRD(2016)·39 citations
  3. 06

    [Submitted on 19 Sept 2015] (cross-list from astro-ph.HE)

    Cooling compact stars and phase transitions in dense QCD

    Armen Sedrakian

    We report new simulations of cooling of compact stars containing quark cores and updated fits to the Cas A fast cooling data. Our model is built on the assumption that the transient behaviour of the star in Cas A is due to a phase transition within the dense QCD matter in the core of the star. Specifically, the fast cooling is attributed to an enhancement in the neutrino emission triggered by a transition from a fully gapped, two-flavor, red-green color-superconducting quark condensate to a superconducting crystalline or an alternative gapless, color-superconducting phase. The blue colored condensate is modeled as a Bardeen-Cooper-Schrieffer (BCS)-type color superconductor with spin-one pairing order parameter. We study the sensitivity of the fits to the phase transition temperature, the pairing gap of blue quarks and the time-scale characterizing the phase transition (the latter modelled in terms of a width parameter). Relative variations in these parameter around their best fit values larger than spoil the fit to the data. We confirm the previous finding that the cooling curves show significant variations as a function of compact star mass, which allows one to account for dispersion in the data on the surface temperatures of thermally emitting neutron stars.

    Comments:
    v2: minor clarifications and editorial corrections, added references, version in press. v1: 11 pages, 9 figures, submitted to EPJA 2015 Topical Issue on "Exotic Matter in Neutron Stars"
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    1509.06986 [pdf]
    EPJA(2016)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE