Hadrons of N=2 supersymmetric QCD in four dimensions from little string theory

It was recently shown that non-Abelian vortex strings supported in a version of four-dimensional N=2 supersymmetric QCD 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 noncompact Calabi-Yau threefold. In this paper we report on further studies of low-lying closed string states that emerge in four dimensions and identify them as hadrons of our four-dimensional N=2 QCD. We use the approach based on little string theory, describing the critical string on the conifold as a noncritical c=1 string with the Liouville field and a compact scalar at the self-dual radius. In addition to the 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."