2012/11/26 by Daniel Arean, Ioannis Iatrakis, Matti Jarvinen +1 · 1 citation
Physics and Astronomy · #hep-lat #hep-ph #hep-th
paper · pdf · doi:10.1016/j.physletb.2013.01.070
11 pages, 6 figures
arxiv created 2012/11/26 · arxiv updated 2015/06/12
Zero temperature spectra of mesons and glueballs are analyzed in a class of holographic bottom-up models for QCD (named V-QCD), as a function of x = Nf/Nc with the full back-reaction included. It is found that spectra are discrete and gapped (modulo the pions) in the QCD regime, for x below the critical value xc where the conformal transition takes place. The masses uniformly converge to zero in the walking region x -> xc due to Miransky scaling. The ratio of masses all asymptote to non-zero constants as x -> xc and therefore there is no "dilaton" in the spectrum. The S-parameter is computed and found to be of O(1) in the walking regime.