EVH Black Hole Solutions With Higher Derivative Corrections

We analyze the effect of higher derivative corrections to the near horizon geometry of the extremal vanishing horizon (EVH) black hole solutions in four dimensions. We restrict ourselves to the Gauss-Bonnet correction with a dilation dependent coupling in an Einstein Maxwell dilaton theory. This action may represent the effective action as it arises in tree level heterotic string theory compactified to four dimensions or the K3 compactification of type II string theory. We show that EVH black holes, in this theory, develop an AdS3 throat in their near horizon geometry.Comment: 15 page

Dyonic solution of Horava-Lifshitz Gravity

Recently proposed Horava-Lifshitz gravity promises a UV completion of Einstein's theory by sacrificing general covariance at short distances and introducing anisotropic spacetime scaling. Here we present a dyonic solution by coupling this theory to a vector field and we discuss some properties of solution.Comment: 7 page

Charged Black Branes with Hyperscaling Violating Factor

We present an analytic solution of a charged black hole with hyperscaling violating factor in an Einstein-Maxwell-Dilaton model where the scalar potential is key to the existence of a solution. This solution provides a candidate gravitational description of theories with hyperscaling violation at both finite temperature and finite charge density. Using this background we explore certain features of these theories via AdS/CFT correspondence. Finally, we discuss embeddings based on the well-known sphere reductions of ten and eleven-dimensional supergravity.Comment: 1+21 pages, section on optical conductivity added, references corrected, agrees with published versio

Embedding the modified CYBE in Supergravity

It has recently been demonstrated that the Classical Yang-Baxter Equation (CYBE) emerges from supergravity via the open-closed string map. Thus, given any solution with an isometry group, there exists a deformed solution based on an $r$-matrix solution to the homogeneous CYBE. In this work, we argue that the CYBE emerges exclusively from the NS sector, while the RR sector acts largely as a spectator that supports the spacetimes. Moreover, shifting the dilaton by a constant, one can incorporate $r$-matrix solutions to the modified CYBE, but only for original geometries that are a direct-product of coset spaces. We illustrate our solution generating technique with deformations of $AdS_3 \times S^3 \times M_4$, where $M_4 = T^4$ (K3) and $S^3 \times S^1$, and explicitly construct one and two-parameter (integrable) q-deformations that are solutions to generalised supergravity.Comment: 27 pages; v2 references updated, typos corrected; v3 matches published versio