Holographic approach to deformations of NS5-brane distributions and exact CFTs

We consider general planar deformations of a circular distribution of NS5-branes. The near-horizon region of the latter admits, after a T-duality transformation, an exact conformal-field-theory description in terms of the coset model SU(2)/U(1) X SL(2,R)/U(1). We derive the exactly marginal operators corresponding to an infinitesimal planar deformation using the conjectured holography between the coset model and the little string theory that resides on the worldvolume of the NS5-branes. Subsequently, we perform a complementary analysis of the same deformations using the associated N=1 supersymmetric sigma model and verify the holographic correspondence. We explicitly demonstrate a precise match between the two approaches which rests upon a delicate interplay between exact conformal-field-theory operators and their semiclassical realizations in terms of target-space variables.