The chiral condensate in holographic models of QCD

TL;DR

This paper critically examines the assumptions in holographic QCD models, revealing inconsistencies in how they match parameters to QCD at high energies, especially affecting the calculation of the chiral condensate.

Contribution

It analyzes the reliability of parameter matching in bottom-up holographic QCD models and highlights resulting phenomenological and theoretical issues.

Findings

Inconsistencies in scale-dependent quantities like the chiral condensate.

Problems with parameter matching at high momentum scales.

Implications for the phenomenological success of holographic QCD models.

Abstract

Bottom-up holographic models of QCD, inspired by the AdS/CFT correspondence, have shown a remarkable degree of phenomenological success. However, they rely on a number of bold assumptions. We investigate the reliability of one of the key assumptions, which involves matching the parameters of these models to QCD at high 4D momentum $q^2$ and renormalization scale $\mu^2$. We show that this leads to phenomenological and theoretical inconsistencies for scale-dependent quantities such as $\bra \bar{q}q\ket$