Holographic Entanglement Entropy for Excited States in Two Dimensional CFT

We use holographic methods to study the entanglement entropy for excited states in a two dimensional conformal field theory. The entangling area is a single interval and the excitations are produced by in and out vertex operators with given scaling dimensions. On the gravity side we provide the excitations by turning on a scalar field with an appropriate mass. The calculation amounts to using the gravitational background, with a singular boundary, to find the one point function of the vertex operators. The singular boundary is taken care of by introducing a nontrivial UV regulator surface to calculate gravitational partition functions. By means of holographic methods we reproduce the field theory results for primary excitations.