Hossein Yavartanoo

Charged black branes with hyperscaling violating factor

A bstractWe 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.

On holography with hyperscaling violation

A bstractWe study certain features of strongly coupled theories with hyperscaling violation by making use of their gravitational duals. We will consider models with an anisotropic scaling in time or in one of spatial directions. In particular for the case where the anisotropic scaling is along a spatial direction we will compute the holographic entanglement entropy and show that for specific values of the parameters it exhibits a logarithmic violation of the area law. We will also probe the backgrounds by different closed and open strings which in turn can be used to read, for example, effective potential of an external object, drag force and etc.

EVH black holes, AdS3 throats and EVH/CFT proposal

Within class of generic black holes there are extremal black holes (with vanishing Hawking temperature T) and vanishing horizon area Ah, but with finite Ah/T ratio, the Extremal Vanishing Horizon (EVH) black holes. We study the near horizon limit of a four dimensional EVH black hole solution to a generic (gauged) Einstein-Maxwell dilaton theory and show that in the near horizon limit they develop a throat which is a pinching orbifold limit of AdS3. This is an extension of the well known result for extremal black holes the near horizon limit of which contains an AdS2 throat. We show that in the near EVH near horizon limit the pinching AdS3 factor turns to a pinching BTZ black hole and that this near horizon limit is indeed a decoupling limit. We argue that the pinching AdS3 or BTZ orbifold is resolved if the near horizon limit is accompanied by taking the 4d Newton constant G4 to zero such that the Bekenstein-Hawking entropy Su2009=u2009Ah/(4G4) remains finite. We propose that in this limit the near horizon EVH black hole is dual to a 2d CFT. We provide pieces of evidence in support of the EVH/CFT correspondence and comment on its connection to the Kerr/CFT proposal and speculation show the EVH/CFT maybe used to study generic e.g. Schwarzchild-type black holes.

On the generality of the LLM geometries in M-theory

In this note we revisit the Lin, Lunin, Maldacena (LLM) class of d = 11 supergravity solutions with symmetry SO(6) × SO(3) × R, but generalise to allow for all fluxes consistent with the isometries. Using the Killing spinor equation, we prove there are no supersymmetric geometries with additional fluxes beyond the LLM ansatz. In addition, the LLM relationship between Killing spinors, ϵ− = − γ5ϵ+, may be seen as a consequence of identifying two Killing directions identified through the Killing spinor equation corresponding to candidate R-symmetry directions.

Fermionic T-duality in the pp-wave limit

AdS5u2009×u2009S5 and its pp-wave limit are self-dual under transformations involving eight fermionic T-dualities, a property which accounts for symmetries seen in scattering amplitudes in

Near-extremal vanishing horizon AdS5 black holes and their CFT duals

mathcal{N} = 4

EVH black hole solutions with higher derivative corrections

super-Yang-Mills. Despite strong evidence for similar symmetries in the amplitudes of three-dimensional

On EVH black hole solution in heterotic string theory

mathcal{N} = 6

Supersymmetric AdS3 × S2 M-theory geometries with fluxes

ABJM theory,a corresponding self-duality in the dual geometry

Five-dimensional heterotic black holes and its dual IR-CFT

Ad{S_4} times mathbb{C}{P^3}