Infrared Dynamics of a Large N QCD Model, the Massless String Sector and Mesonic Spectra

TL;DR

This paper uses a UV complete string theory model to analyze IR mesonic spectra in large N QCD, validating supergravity approaches and comparing results with established models like Sakai-Sugimoto.

Contribution

It provides a novel IR analysis of mesonic spectra from a UV complete model and explores landscape points that improve spectral predictions.

Findings

Massless string sector spectra are UV-independent.

Certain landscape points improve spectral predictions.

Background supergravity components are constrained by spectral consistency.

Abstract

A consistency check for any UV complete model for large N QCD should be, among other things, the existence of a well-defined vector and scalar mesonic spectra. In this paper, we use our UV complete model in type IIB string theory to study the IR dynamics and use this to predict the mesonic spectra in the dual type IIA side. The advantage of this approach is two-fold: not only will this justify the consistency of the supergravity approach, but it will also give us a way to compare the IR spectra and the model with the ones proposed earlier by Sakai and Sugimoto. Interestingly, the spectra coming from the massless stringy sector are independent of the UV physics, although the massive string sector may pose certain subtleties regarding the UV contributions as well as the mappings to actual QCD. Additionally, we find that a component of the string landscape enters the picture: there are points in the landscape where the spectra can be considerably improved over the existing results in the literature. These points in the landscape in-turn also determine certain background supergravity components and fix various pathologies that eventually lead to a consistent low energy description of the theory.