Holographic Descriptions Of QCD

TL;DR

This thesis develops a holographic model of QCD combining top-down supergravity solutions and bottom-up extensions, successfully reproducing meson properties and hadronization data with high accuracy.

Contribution

It introduces a hybrid holographic QCD model that captures chiral symmetry breaking, meson spectra, and hadronization phenomena with improved precision.

Findings

Reproduces lightest meson masses and decay constants within 10%.

Achieves 2% accuracy for rho meson masses.

Matches hadronization data across four orders of magnitude.

Abstract

In this thesis we investigate proposed duals to QCD. Duals to QCD fall into two categories: `top-down' and `bottom-up'. We take inspiration from both by truncating a consistent solution to the type IIB supergravity equations of motion (top-down). This model demonstrates dynamical chiral symmetry breaking, has a running coupling and contains a holographic description of the vector meson sector. By artificially extending the existing U(1) symmetry to SU(2) (bottom-up) we then obtain a holographic description of the axial vector sector. We show that this model reproduces the masses and decay constants of the lightest mesons to the 10% level. By regulating the UV with a sharp cut-off we can reproduce the rho meson masses to within 2%. Finally we demonstrate that this model can be used to reproduce a very good agreement with hadronization data for particle production over a range of four orders of magnitude.