IR Dynamics of d=2, N=(4,4) Gauge Theories and DLCQ of "Little String Theories"

Abstract

We analyze the superconformal theories (SCFTs) which arise in the low-energy limit of N=(4,4) supersymmetric gauge theories in two dimensions, primarily the Higgs branch SCFT. By a direct field theory analysis we find a continuum of "throat"-like states localized near the singularities of the Higgs branch. The "throat" is similar to the "throat" found in the Coulomb branch of the same theories, but the full superconformal field theories of the two branches are different. A particular example is the SCFT of the R^4/Z_2 sigma model with zero theta angle. In the application of the Higgs branch SCFTs to the DLCQ description of "little string theories" (LSTs), the "throat" continuum is identified with the continuum of "throat" states in the holographic description of the LSTs. We also match the descriptions of the string interactions (in the "throat" region) in the DLCQ and holographic descriptions of the N=(2,0) LSTs.Comment: 37 pages, harvmac. v2: very minor change