Hadrons of N=2 Supersymmetric QCD in Four Dimensions from Little String Theory

TL;DR

This paper explores how certain non-Abelian vortex strings in four-dimensional N=2 supersymmetric QCD can be viewed as critical superstrings, revealing hadron-like states through a novel approach based on little string theory.

Contribution

It demonstrates the emergence of hadron-like states from vortex strings in N=2 SQCD using little string theory, including massive multiplets and a new perspective on holography.

Findings

Identification of massive vector and spin-2 multiplets as hadrons.

Observation of non-BPS states in the string spectrum.

Interpretation of states as baryons with confined monopoles.

Abstract

It was recently shown that non-Abelian vortex strings supported in a version of four-dimensional N=2 supersymmetric QCD (SQCD) become critical superstrings. In addition to four translational moduli, non-Abelian strings under consideration have six orientational and size moduli. Together they form a ten-dimensional target space required for a superstring to be critical, namely, the product of the flat four-dimensional space and conifold -- a non-compact Calabi-Yau threefold. In this paper we report on further studies of low-lying closed string states which emerge in four dimensions and identify them as hadrons of our four-dimensional N=2 SQCD. We use the approach based on "little string theory," describing critical string on the conifold as a non-critical $c=1$ string with the Liouville field and a compact scalar at the self-dual radius. In addition to massless hypermultiplet found earlier we observe several massive vector multiplets and a massive spin-2 multiplet, all belonging to the long (non-BPS) representations of N=2 supersymmetry in four dimensions. All the above states are interpreted as baryons formed by a closed string with confined monopoles attached. Our construction presents an example of a "reverse holography."