Quark mass and condensate in HQCD

TL;DR

This paper extends the Sakai-Sugimoto holographic QCD model by incorporating a scalar field that accounts for quark masses and chiral symmetry breaking, reproducing key QCD relations.

Contribution

It introduces a scalar bi-fundamental field into the HQCD model, linking it to quark mass generation and chiral symmetry breaking mechanisms.

Findings

Scalar field induces spontaneous chiral symmetry breaking.

Reproduces Gell-Mann-Oakes-Renner relation for pion mass.

Provides a holographic understanding of quark mass effects.

Abstract

We extend the Sakai-Sugimoto holographic model of QCD (HQCD) by including the scalar bi-fundamental "tachyon" field in the 8-brane-anti-8-brane probe theory. We show that this field is responsible both for the spontaneous breaking of the chiral symmetry, and for the generation of (current algebra) quark masses, from the point of view of the bulk theory. As a by-product we show how this leads to the Gell-Mann- Oakes-Renner relation for the pion mass.