Subcritical String and Large N QCD

TL;DR

This paper explores using subcritical string theory in four dimensions as a dual description of large N QCD, analyzing open string loops to infer closed string spectra and gauge theory behavior.

Contribution

It proposes that the Neveu-Schwarz dual resonance model's open string dynamics can determine an appropriate subcritical closed string theory for large N QCD.

Findings

One-loop open string diagram reveals the closed string spectrum at weak coupling.

Field theory limit reproduces the correct running coupling behavior of QCD.

Higher loop diagrams are needed to understand closed string interactions.

Abstract

We pursue the possibility of using subcritical string theory in 4 space-time dimensions to establish a string dual for large N QCD. In particular we study the even G-parity sector of the 4 dimensional Neveu-Schwarz dual resonance model as the natural candidate for this string theory. Our point of view is that the open string dynamics given by this model will {\it determine} the appropriate subcritical closed string theory, a tree level background of which should describe the sum of planar multi-loop open string diagrams. We examine the one loop open string diagram, which contains information about the closed string spectrum at weak coupling. Higher loop open string diagrams will be needed to determine closed string interactions. We also analyze the field theory limit of the one loop open string diagram and recover the correct running coupling behavior of the limiting gauge theory.