Chiral lagrangians and the QCD string

TL;DR

This paper introduces a method to derive the low-energy effective action of QCD using a string theory approach, addressing common issues by employing a sigma model and conformal invariance to determine effective lagrangian coefficients.

Contribution

It presents a novel approach combining string theory and sigma models to derive QCD effective actions, overcoming traditional problems like tachyons and Adler zero.

Findings

Two-dimensional conformal invariance leads to vanishing of certain effective lagrangian coefficients.

The method provides a new perspective on the low-energy behavior of QCD.

Discussion of potential extensions beyond the current limit.

Abstract

We propose a method to derive the low-energy efective action of QCD assuming that the long-distance properties of strong interactions can be described by a string theory. We bypass the usual problems related to the existence of the tachyon and absence of the adequate Adler zero by using a sigma model approach where excitations above the correct (chirally non-invariant) QCD vacuum are included. Two-dimensional conformal invariance then implies the vanishing of the O(p^4) effective lagrangian coefficients. We discuss ways to go beyond this limit.