Boundary entropy of supersymmetric Janus solutions

TL;DR

This paper calculates the boundary entropy for supersymmetric Janus solutions in type IIB supergravity, showing exact agreement with CFT results for dilaton jumps and partial agreement for axion jumps, advancing understanding of holographic interfaces.

Contribution

It provides the first exact holographic computation of boundary entropy for supersymmetric Janus solutions and compares it with CFT results, including cases with axion jumps.

Findings

Exact match between holographic and CFT results for dilaton jumps.

Partial agreement at leading order for non-supersymmetric Janus solutions.

Holographic results for axion jumps relate to $Z_2$-orbifold twist deformations.

Abstract

In this paper we compute the holographic boundary entropy for half-BPS Janus deformations of the $AdS_3\times S^3\times T^4$ vacuum of type IIB supergravity. Previous work \cite{Chiodaroli:2009yw} has shown that there are two independent deformations of this sort. In one case, the six-dimensional dilaton jumps across the interface, while the other case displays a jump of axion and four-form potential. In case of a jump of the six-dimensional dilaton, it is possible to compare the holographic result with the weak-coupling result for a two-dimensional interface CFT where the radii of the compactified bosons jump across the interface. We find exact agreement between holographic and CFT results. This is to be contrasted with the holographic calculation for the non-supersymmetric Janus solution, which agrees with the CFT result only at the leading order in the jump parameter. We also examine the implications of the holographic calculation in case of a solution with a jump in the axion, which can be associated with a deformation of the CFT by the $Z_2$-orbifold twist operator.