Hadrons in AdS/QCD models

TL;DR

This paper explores how gauge/gravity duality models can effectively describe the spectrum and decay properties of light hadrons, providing insights into their mass trajectories and decay widths.

Contribution

It compares two 5D AdS/QCD models with infrared modifications, demonstrating their ability to produce linear Regge trajectories and realistic decay widths for light mesons.

Findings

Models produce linear Regge trajectories for light mesons.

Decay widths of f0 mesons into pions agree qualitatively with experimental data.

Infrared deformations enable mass gaps while maintaining near-conformal boundary behavior.

Abstract

We discuss applications of gauge/gravity duality to describe the spectrum of light hadrons. We compare two particular 5-dimensional approaches: a model with an infrared deformed Anti-de Sitter metric and another one based on a dynamical AdS/QCD framework with back-reacted geometry in a dilaton/gravity background. The models break softly the scale invariance in the infrared region and allow mass gap for the field excitations in the gravity description, while keeping the conformal property of the metric close to the four-dimensional boundary. The models provide linear Regge trajectories for light mesons, associated with specially designed infrared gravity properties. We also review the results for the decay widths of the f0's into two pions, as overlap integrals between mesonic string amplitudes, which are in qualitative agreement with data.