Effective holographic models for QCD: glueball spectrum and trace anomaly

TL;DR

This paper develops effective holographic models for QCD using five-dimensional Dilaton-Gravity, successfully reproducing glueball spectra consistent with lattice data and elucidating the trace anomaly and beta function behavior.

Contribution

It introduces semi-analytic interpolations in holographic QCD models that match lattice glueball spectra and connects trace anomalies with QCD beta functions.

Findings

Glueball spectra align with lattice QCD data.

Derived a universal trace anomaly for deformed CFTs.

Revealed a beta function similar to two-loop perturbative QCD.

Abstract

We investigate effective holographic models for QCD arising from five dimensional Dilaton-Gravity. The models are characterized by a dilaton with a mass term in the UV, dual to a CFT deformation by a relevant operator, and quadratic in the IR. The UV constraint leads to the explicit breaking of conformal symmetry whereas the IR constraint guarantees linear confinement. We propose semi-analytic interpolations between the UV and the IR and obtain a spectrum for scalar and tensor glueballs consistent with lattice QCD data. We use the glueball spectrum as a physical constraint to find the evolution of the model parameters as the mass term goes to zero. Finally, we reproduce the universal result for the trace anomaly of deformed CFTs and propose a dictionary between this result and the QCD trace anomaly. A nontrivial consequence of this dictionary is the emergence of a $\beta$ function similar to the two-loop perturbative QCD result.