Little string theory from double-scaling limits of field theories

We show that little string theory on S5 can be obtained as double-scaling limits of the maximally supersymmetric Yang-Mills theories on R × S2 and R × S3/Zk. By matching the gauge theory parameters with those in the dual supergravity solutions found by Lin and Maldacena, we determine the limits in the gauge theories that correspond to decoupling of NS5-brane degrees of freedom. We find that for the theory on R × S2, the 't Hooft coupling must be scaled like ln 3N, and on R × S3/Zk, like ln 2N. Accordingly, taking these limits in these field theories gives Lagrangian definitions of little string theory on S5.