Chiral Limit of 2d QCD Revisited with Lightcone Conformal Truncation

TL;DR

This paper uses Lightcone Conformal Truncation to analyze the chiral limit of 2d QCD, successfully capturing the spectrum and correlation functions of the Sine-Gordon model, and enabling studies of integrable CFT deformations.

Contribution

It introduces a modified LCT basis for small quark masses, restoring convergence and accurately describing the IR behavior with the Sine-Gordon model.

Findings

LCT numerics match Sine-Gordon spectrum and correlators

Modified basis improves convergence for small quark masses

Potential to study deformations of integrable CFTs

Abstract

We study the chiral limit of 2d QCD with a single quark flavor at finite $N_c$ using LCT. By modifying the LCT basis according to the quark mass in a manner motivated by 't Hooft's analysis, we are able to restore convergence for quark masses much smaller than the QCD strong coupling scale. For such small quark masses, the IR of the theory is expected to be well described by the Sine-Gordon model. We verify that LCT numerics are able to capture in detail the spectrum and correlation functions of the Sine-Gordon model. This opens up the possibility for studying deformations of various integrable CFTs using LCT by considering the chiral limit of QCD like theories.