Stringy effects in four-dimensional N = 2 supersymmetric QCD from 2D-4D correspondence

In this talk we are going to discuss recent results on non-Abelian vortex strings in four-dimensional (4D) N = 2 supersymmetric QCD with U(N = 2) gauge group and Nf = 4 flavors of quark hypermultiplets. It has been recently shown that these vortices behave as critical superstrings. In particular, the lowest string state appears to be a massless BPS “baryon.” Here we confirm the existence of this stringy baryon using purely field-theoretic methods. To this end we study the conformal world-sheet theory on the non-Abelian string – the so called weighted N = (2, 2) supersymmetric CP model. Then we use the 2D-4D correspondence to show that a marginal deformation of the target space is associated with the emergence of a non-perturbative Higgs branch in 4D theory which opens up at strong coupling. The modulus parameter on this Higgs branch is the vacuum expectation value of the massless BPS “baryon” previously found in string theory. Moreover, we explicitly demonstrate the occurrence of the so-called “instead-of-confinement” phase. Based on the talk given at the XXIV International Scientific Conference of Young Scientists and Specialists (AYSS-2020).