Glueballs and deconfinement temperature in AdS/QCD

Abstract

We put forward an alternative way to estimate the deconfinement temperature in bottom-up holographic models. The deconfinement in anti-de Sitter (AdS)/QCD is related to the Hawking-Page phase transition, in which the critical Hawking temperature is identified with the deconfinement one in the gauge theory. The numeric estimation of the latter is only possible when the parameters of a five-dimensional dual model are previously determined from consistency with other physical aspects, standardly, providing a description of the QCD resonances. The traditional way to fix parameters in the simplest AdS/QCD models is to reproduce the mass of the ρ meson or the slope of the approximate radial Regge trajectory of the ρ excitations. Motivated by a general idea that the slope value originates in gluodynamics, we propose calculating the deconfinement temperature using the trajectory of scalar glueballs. We consider several holographic models and use the recent idea of isospectral potentials to make an additional check of the relevance of our approach. It is demonstrated that different models from an isospectral family (i.e. the models leading to identical predictions for spectrum of hadrons with fixed quantum numbers) result in different predictions for the deconfinement temperature. This difference is found to be quite small in the scalar glueball channel but very large in the vector meson channel. The observed stability in the former case clearly favours the choice of the glueball channel for thermodynamic predictions in AdS/QCD models. For a balanced approach, we argue that either assuming f 0 (1500) to have a dominating component of 0 ++ glueball or accepting the idea of the universality in the radial Regge trajectories of light non-strange vector mesons one can reproduce the results for the deconfinement temperature obtained before in the lattice simulations in the background of non-dynamical quarks.

Fluctuation and dissipation from a deformed string/gauge duality model

“…In Refs. [70][71][72][73][74][75][76]78] this metric was used to study many aspects of holographic high energy physics. In these references, k is a constant that can be related to Λ QCD .…”

“…Within this approach one can calculate quarkantiquark potential at zero and finite temperature, hadronic spectra, etc. [70][71][72][73][74][75][76][77][78][79].…”

“…The main goal of this work is to study zero and finite temperature string fluctuations using a deformed AdS space with the introduction of an exponential factor exp k=r 2 in the metric, motivated by the success of this approach to hadronic physics [70][71][72][73][74][75][76][77][78][79]. We calculate thermal fluctuations, the admittance from linear response, and two-point functions, and we show explicitly that the fluctuationdissipation theorem holds in this setup.…”

Proton structure functions from an AdS/QCD model with a deformed background

“…Such a deformation was considered before in a wide range of AdS/ QCD studies, as can be seen in Refs. [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]. Our DIS structure functions are compared with experimental data showing good agreement for large x.…”

The Effect of Higher Dimensional QCD Operators on the Spectroscopy of Bottom-Up Holographic Models

“…The area of research included the studies of glueball sector [34][35][36], relations with light-front QCD (reviewed in [4]) and with QCD sum rules [37][38][39], important subjects of hadron formfactors (for a review, see references [4,40]) and gluon parton densities [41]. The bottom-up holographic study of a QCD phase diagram was initiated in reference [42] and gave rise to an interesting spin-off direction (for a review, see references [43,44]).…”