PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·January 21, 2015

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    [Submitted on 19 Jan 2015] (cross-list from hep-ph)

    Color confinement and screening in the -vacuum

    Dmitri E. Kharzeev🇺🇸 · Eugene M. Levin🇨🇱

    QCD perturbation theory ignores the compact nature of gauge group that gives rise to the periodic -vacuum of the theory. We propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the -vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a "glost". We evaluate the glost propagator and find that it has the form where is the Yang-Mills topological susceptibility related to the mass by Witten-Veneziano relation; this propagator describes confinement of gluons at distances fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at , but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. Our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.

    Comments:
    7 pages, 4 figures; slightly extended version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1501.04622 [pdf]
    PRL(2015)·39 citations
  2. 04

    [Submitted on 19 Jan 2015] (cross-list from hep-th)

    Holography and off-center collisions of localized shock waves

    Paul M. Chesler🇺🇸 · Laurence G. Yaffe🇺🇸

    Using numerical holography, we study the collision, at non-zero impact parameter, of bounded, localized distributions of energy density chosen to mimic relativistic heavy ion collisions, in strongly coupled N = 4 supersymmetric Yang-Mills theory. Both longitudinal and transverse dynamics in the dual field theory are properly described. Using the gravitational description we solve 5D Einstein equations, without dimensionality reducing symmetry restrictions, to find the asymptotically anti-de Sitter spacetime geometry. Implications of our results on the understanding of early stages of heavy ion collisions, including the development of transverse radial flow, are discussed.

    Comments:
    Enlarged JHEP version, 14 pages
    Subjects:
    High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1501.04644 [pdf]
    JHEP(2015)·98 citations
  3. 05

    [Submitted on 19 Jan 2015] (cross-list from hep-th)

    Holographic Baryons and Instanton Crystals

    Vadim Kaplunovsky🇺🇸 · Dmitry Melnikov🇧🇷 · Jacob Sonnenschein🇮🇱

    In a wide class of holographic models, like the one proposed by Sakai and Sugimoto, baryons can be approximated by instantons of non-abelian gauge fields that live on the world-volume of flavor D-branes. In the leading order, those are just the Yang-Mills instantons, whose solutions can be obtained from the celebrated ADHM construction. This fact can be used to study various properties of baryons in the holographic limit. In particular, one can attempt to construct a holographic description of the cold dense nuclear matter phase of baryons. It can be argued that holographic baryons in such a regime are necessarily in a solid crystalline phase. In this review we summarize the known results on the construction and phases of crystals of the holographic baryons.

    Comments:
    66 pages, 16 figures. Prepared for the special issue "Skyrmion" of the IJMPB, edited by M. Rho and I. Zahed
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
    arXiv:
    1501.04655 [pdf]
    Mod.Phys.Lett.B(2015)·30 citations
  4. 06

    [Submitted on 20 Jan 2015] (cross-list from hep-ph)

    Fluctuating Heavy Quark Energy Loss in Strongly-Coupled Quark-Gluon Plasma

    W. A. Horowitz🇿🇦

    Results from an energy loss model that includes thermal fluctuations in the energy loss for heavy quarks in a strongly-coupled plasma are shown to be qualitatively consistent with single particle data from both RHIC and LHC. The model used is the first to properly include the fluctuations in heavy quark energy loss as derived in string theory and that do not obey the usual fluctuation-dissipation relations. These fluctuations are crucial for simultaneously describing both RHIC and LHC data; leading order drag results without fluctuations are falsified by current data. Including the fluctuations is non-trivial and relies on the Wong-Zakai theorem to fix the numerical Langevin implementation. The fluctuations lead to surprising results: B meson anisotropy is similar to that for D mesons at LHC, and the double ratio of D to B meson nuclear modification factors approaches unity more rapidly than even predictions from perturbative energy loss models. It is clear that future work in improving heavy quark energy loss calculations in AdS/CFT to include all energy loss channels is needed and warranted.

    Comments:
    12 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1501.04693 [pdf]
    PRD(2015)·65 citations

Affiliations

first authorsco-authorsvia INSPIRE