Holographic models and the QCD trace anomaly

TL;DR

This paper explores five-dimensional holographic models as duals to pure gauge QCD, analyzing the trace anomaly, confinement, and gluon condensate through exact solutions with different dilaton potentials.

Contribution

It provides a detailed holographic analysis of the QCD trace anomaly using exact solutions for perturbative and non-perturbative beta-functions, highlighting their physical implications.

Findings

Perturbative model is not asymptotically AdS.

Non-perturbative model exhibits confinement and gluon condensate.

Both models analyze trace anomaly and Wilson loops.

Abstract

Five dimensional dilaton models are considered as possible holographic duals of the pure gauge QCD vacuum. In the framework of these models, the QCD trace anomaly equation is considered. Each quantity appearing in that equation is computed by holographic means. Two exact solutions for different dilaton potentials corresponding to perturbative and non-perturbative beta-functions are studied. It is shown that in the perturbative case, where the beta-function is the QCD one at leading order, the resulting space is not asymptotically AdS. In the non-perturbative case, the model considered presents confinement of static quarks and leads to a non-vanishing gluon condensate, although it does not correspond to an asymptotically free theory. In both cases analyses based on the trace anomaly and on Wilson loops are carried out.