Finite temperature holographic duals of 2-dimensional BCFTs

We consider holographic duals of $2$-dimensional conformal field theories in the presence of a boundary, interface, defect and/or junction, referred to collectively as BCFTs. In general, the presence of a boundary reduces the $SO(2,2)$ conformal symmetry to $SO(2,1)$ and the dual geometry is realized as a warped product of the form $AdS_2 \times {\cal M}$, where ${\cal M}$ is not compact. In particular, it will contain points where the warp factor of the $AdS_2$ space diverges, leading to asymptotically $AdS_3$ regions. We show that the $AdS_2$ space-time may always be replaced with an $AdS_2$-"black-hole" space-time. We argue the resulting geometry describes the BCFT at finite temperature. To motivate this claim, we compute the entanglement entropy holographically for a segment centered around the defect or ending on the boundary and find agreement with a known universal formula.Comment: 16 pages, 2 figures; minor corrections and references adde

Integrable systems from supergravity BPS equations

Integrable systems of the sine-Gordon/Liouville type, which arise from reducing the BPS equations for solutions invariant under 16 supersymmetries in Type IIB supergravity and M-theory, are shown to be special cases of an infinite family of integrable systems, parametrized by an arbitrary real function $f$ of a real variable. It is shown that, for each function $f$, this generalized integrable system may be mapped onto a system of linear equations, which in turn may be integrated in terms of the two linearly independent solutions of an ordinary linear second order differential equation which depends only on the function $f$.Comment: 7 page

Holographic two-point functions for Janus interfaces in the D1/D5D1/D5 CFT

This paper investigates scalar perturbations in the top-down supersymmetric Janus solutions dual to conformal interfaces in the $D1/D5$ CFT, finding analytic closed-form solutions. We obtain an explicit representation of the bulk-to-bulk propagator and extract the two-point correlation function of the dual operator with itself, whose form is not fixed by symmetry alone. We give an expression involving the sum of conformal blocks associated with the bulk-defect operator product expansion and briefly discuss finite-temperature extensions. To our knowledge, this is the first two-point function computation for a fully-backreacted, top-down holographic defect.Comment: 30 pages, PDFLaTe

Near Horizon Geometry of Strings Ending on Intersecting D8/D4-branes

We consider solutions of massive IIA supergravity corresponding to the half-BPS intersection of D8/D4-branes with fundamental strings. The $1+1$-dimensional intersection preserves the symmetry $D(2,1;\gamma;1) \times SO(4)$. We give a reduction and partial integration of the BPS equations for this symmetry group. We then specialize to the cases of enhanced supersymmetry corresponding to $\gamma = -1/2,-2$ or $\gamma = 1$. In the first case, we show that the only solution with enhanced symmetry is given by the $AdS_6$ geometry describing the near horizon geometry of D8/D4-branes in the presence of an O8-plane. In the second case, we identify novel solutions corresponding to fundamental strings ending on D8-branes and a second set of novel solutions corresponding to fundamental strings ending on an O8-plane. In both cases, the fundamental string geometry contains an asymptotically flat region where the string coupling goes to zero. We also show that there are no solutions corresponding to $1+0$-dimensional CFTs, which one may have hoped to construct by suspending fundamental strings between D8-branes.Comment: 36 pages, 6 figures (12 pdf figure files