What is the string theory dual to 4d N=2 Super Yang Mills? Motivated by this question, I will revisit some “noncritical” superstring models: these are string theories defined in less than ten spacetime dimensions. Focusing on the setup with 6d Poincare’ invariance, I will explain how a careful worldsheet analysis allows to identify the leading-order effective theories for the lowest modes. These are seven-dimensional, maximally supersymmetric gauged supergravities. The noncritical string can be viewed as a special case of a discrete series of backgrounds labelled by an integer k: the “noncritical” value is k = 2, while for k → ∞ one recovers a weakly-curved 10d target space. We will discuss the worldsheet approach by boundary states and BPS solutions to the supergravity equations of motion. 

Based on 2409.13806 and work in progress in collaboration with Pietro Ferrero and Leonardo Rastelli. 

(online talk)