Chiral Dynamics From AdS Space

TL;DR

This paper models low-energy pion dynamics using a gravity dual approach, deriving a non-linear chiral Lagrangian and computing key physical constants consistent with QCD expectations.

Contribution

It introduces a holographic model with a probe D7 brane in a non-supersymmetric background to study chiral symmetry breaking and pion properties.

Findings

Derived a non-linear chiral Lagrangian from string theory.

Numerically computed quark condensate and pion decay constant.

Found results consistent with naive dimensional analysis.

Abstract

We study the low energy dynamics of pions in a gravity dual of chiral symmetry breaking. The string theory construction consists of a probe D7 brane in the Constable Myers non-supersymmetric background, which has been shown to describe chiral symmetry breaking in the pattern of QCD. We expand the D7 brane's Dirac Born Infeld action for fluctuations that correspond to the Goldstone mode and show that they take the form of a non-linear chiral lagrangian. We numerically compute the quark condensate, pion decay constant and higher order Gasser Leutwyler coefficients. We find their form is consistent with naive dimensional analysis estimates. We also explore the gauging of the quark's chiral symmetries and the vector meson spectrum.