Dynamical Soft-Wall AdS/QCD

TL;DR

This paper introduces a phenomenological holographic QCD model with a soft wall that reproduces linear Regge trajectories and suggests chiral symmetry remains broken at high excitations, providing insights into confinement.

Contribution

It presents a dynamical bottom-up AdS/QCD model with a quadratic dilaton and linear tachyon that captures linear confinement and chiral symmetry behavior.

Findings

Reproduces linear Regge trajectories for meson spectra

Chiral symmetry remains broken for highly excited states

Provides a dynamical holographic model of confinement

Abstract

We present a solution of the five-dimensional gravity-dilaton-tachyon equations of motion with a pure AdS_5 metric and a quadratic dilaton and linear tachyon in conformal coordinates. This leads to an infrared soft wall model where the dilaton profile gives rise to linear Regge trajectories for the four-dimensional mass spectrum of the dual gauge theory. Even though our approach is phenomenological the scalar fields resemble the dilaton and the closed string tachyon of a non-critical string theory. Interestingly, the linear tachyon has the correct profile to imply that chiral symmetry is not restored for highly excited states. Our solution thus provides a dynamical bottom-up model of linear confinement in holographic QCD.