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Title: Some recent advances in the bottom-up holographic approach to QCD

Abstract

We give a brief report on our recent results in the bottom-up holographic approach to QCD. The holographic description of the heavy vector quarkonia and generalization of the Soft Wall model are discussed.

Authors:
 [1]
  1. Saint Petersburg State University, 1 ul. Ulyanovskaya, St. Petersburg, 198504 (Russian Federation)
Publication Date:
OSTI Identifier:
22306063
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1606; Journal Issue: 1; Conference: 2. Russian-Spanish congress on particle and nuclear physics at all scales, astroparticle physics and cosmology, St. Petersburg (Russian Federation), 1-4 Oct 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; HOLOGRAPHY; QUANTUM CHROMODYNAMICS; QUARKONIUM; VECTORS; WALLS

Citation Formats

Afonin, S. S. Some recent advances in the bottom-up holographic approach to QCD. United States: N. p., 2014. Web. doi:10.1063/1.4891151.
Afonin, S. S. Some recent advances in the bottom-up holographic approach to QCD. United States. doi:10.1063/1.4891151.
Afonin, S. S. Wed . "Some recent advances in the bottom-up holographic approach to QCD". United States. doi:10.1063/1.4891151.
@article{osti_22306063,
title = {Some recent advances in the bottom-up holographic approach to QCD},
author = {Afonin, S. S.},
abstractNote = {We give a brief report on our recent results in the bottom-up holographic approach to QCD. The holographic description of the heavy vector quarkonia and generalization of the Soft Wall model are discussed.},
doi = {10.1063/1.4891151},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1606,
place = {United States},
year = {Wed Jul 23 00:00:00 EDT 2014},
month = {Wed Jul 23 00:00:00 EDT 2014}
}
  • Recent progress in constructing holographic models for QCD is discussed, concentrating on the bottom-up models which implement holographically the renormalization group flow of QCD. The dynamics of gluons can be modeled by using a string-inspired model termed improved holographic QCD, and flavor can be added by introducing space filling branes in this model. The flavor fully backreacts to the glue in the Veneziano limit, giving rise to a class of models which are called V-QCD. The phase diagrams and spectra of V-QCD are in good agreement with results for QCD obtained by other methods.
  • One of the most known result of the string theory consists in the idea that some strongly coupled gauge theories may have a dual description in terms of a higher dimensional weakly coupled gravitational theory — the so-called AdS/CFT correspondence or gauge/gravity correspondence. The attempts to apply this idea to the real QCD are often referred to as “holographic QCD” or “AdS/QCD approach”. One of directions in this field is to start from the real QCD and guess a tentative dual higher dimensional weakly coupled field model following the principles of gauge/gravity correspondence. The ensuing phenomenology can be then developedmore » and compared with experimental data and with various theoretical results. Such a bottom-up holographic approach turned out to be unexpectedly successful in many cases. In the given short review, the technical aspects of the bottom-up holographic approach to QCD are explained placing the main emphasis on the soft wall model.« less
  • A complementary approach, derived from (a) higher-dimensional anti-de Sitter (AdS) space, (b) light-front quantization and (c) the invariance properties of the full conformal group in one dimension leads to a nonperturbative relativistic light-front wave equation which incorporates essential spectroscopic and dynamical features of hadron physics. The fundamental conformal symmetry of the classical QCD Lagrangian in the limit of massless quarks is encoded in the resulting effective theory. The mass scale for confinement emerges from the isomorphism between the conformal group andSO(2,1). This scale appears in the light-front Hamiltonian by mapping to the evolution operator in the formalism of de Alfaro,more » Fubini and Furlan, which retains the conformal invariance of the action. Remarkably, the specific form of the confinement interaction and the corresponding modification of AdS space are uniquely determined in this procedure.« less
  • An SU(N{sub f})xSU(N{sub f}) Yang-Mills theory on an extra-dimensional interval is considered, with appropriate symmetry-breaking boundary conditions on the IR brane. UV-brane to UV-brane correlators at high energies are compared with the OPE of two-point functions of QCD quark currents. Condensates correspond to departure from the AdS metric of the (different) metrics felt by vector and axial combinations, away from the UV brane. Their effect on hadronic observables is studied: the extracted condensates agree with the signs and orders of magnitude expected from QCD.
  • We study scalar glueballs and scalar mesons at T{ne}0 in the soft wall holographic QCD model. We find that, using the anti-de Sitter-black-hole metric for all values of the temperature, the masses of the hadronic states decrease and the widths become broader when T increases, and there are temperatures for which the states disappear from the scalar glueball and scalar meson spectral functions. However, the values of the temperatures in correspondence of which such phenomena occur are low, of the order of 40-60 MeV. A consistent holographic description of in-medium effects on hadron properties should include the Hawking-Page transition, whichmore » separates the phase with the anti-de Sitter metric at small temperatures from the phase with anti-de Sitter-black-hole metric at high temperatures.« less