68 research outputs found
Subleading Correction to Statistical Entropy for BMPV Black Hole
We study higher derivative corrections to the statistical entropy function
and the statistical entropy for five dimensional BMPV black holes by doing the
asymptotic expansion of the partition function. This enables us to evaluate
entropy for a large range of charges, even out of Cardy (Farey tail) limit.Comment: 0+11 pages, V2, one section added, typos correcte
(Un)attractor black holes in higher derivative AdS gravity
We investigate five-dimensional static (non-)extremal black hole solutions in
higher derivative Anti-de Sitter gravity theories with neutral scalars
non-minimally coupled to gauge fields. We explicitly identify the boundary
counterterms to regularize the gravitational action and the stress tensor. We
illustrate these results by applying the method of holographic renormalization
to computing thermodynamical properties in several concrete examples. We also
construct numerical extremal black hole solutions and discuss the attractor
mechanism by using the entropy function formalism.Comment: 30 pages, 4 figures; V2: comments on holographic renormalization
method and ack. added, misprints corrected, expanded reference
Conformal Structure of Massless Scalar Amplitudes Beyond Tree level
We show that the one-loop on-shell four-point scattering amplitude of
massless scalar field theory in 4D Minkowski space time, when Mellin
transformed to the Celestial sphere at infinity, transforms covariantly under
the global conformal group () on the sphere. The unitarity of the
four-point scalar amplitudes is recast into this Mellin basis. We show that the
same conformal structure also appears for the two-loop Mellin amplitude.
Finally we comment on some universal structure for all loop four-point Mellin
amplitudes specific to this theory.Comment: 15 pages, 4 figures, V2: Reference Adde
The off-shell c-map
The off-shell version of the c-map is presented, based on a systematic
off-shell reduction from four to three space-time dimensions for supergravity
theories with eight supercharges. In the reduction, the R-symmetry group is
enhanced to local [SU(2) x SU(2)]/Z2 =SO(4) and the c-map is effected by a
parity transformation in the internal space that interchanges the two SU(2)
factors. Vector and tensor supermultiplets are each others conjugate under the
c-map and both can be dualized in three dimensions to (on-shell)
hypermultiplets. As shown in this paper the off-shell formulation indeed leads
to a clarification of many of the intricate issues that play a role in the
c-map. The results for off-shell Lagrangians quadratic in space-time
derivatives are analyzed in detail and compared to the literature. The
underlying reasons are identified why not all of the four-dimensional tensor
multiplet Lagrangians can be in the image of the c-map. The advantage of the
off-shell approach is, that it also enables a systematic analysis of theories
with higher-derivative couplings. This is demonstrated for a particular
subclass of such theories, which, under certain conditions, are consistent
under the c-map. In principle, explicit results for realistic four-dimensional
type-II string compactifications can be explored in this way.Comment: 57 page
Near-Horizon Analysis of
It is now well understood that the coefficient of shear viscosity of boundary
fluid can be obtained from the horizon values of the effective coupling of
transverse graviton in bulk spacetime. In this paper we observe that to find
the shear viscosity coefficient it is sufficient to know only the near horizon
geometry of the black hole spacetime. One does not need to know the full
analytic solution. We consider several examples including non-trivial matter
(dilaton, gauge fields) coupled to gravity in presence of higher derivative
terms and calculate shear viscosity for both extremal and non-extremal black
holes only studying the near horizon geometry. In particular, we consider
higher derivative corrections to extremal R-charged black holes and compute
in presence of three independent charges. We also consider
asymptotically Lifshitz spacetime whose dual black hole geometry can not be
found analytically. We study the near horizon behaviour of these black holes
and find for its dual plasma at Lifshitz fixed point.Comment: 17 page
Maximally -extended super-BMS algebras and Generalized 3D Gravity Solutions
We consider the maximal extended supergravity theory in 3
dimensions with fermionic generators transforming under real but non
necessarily irreducible representations of the internal algebra. We obtain the
symmetry algebra at null infinity preserving boundary conditions of
asymptotically flat solutions, i.e. the maximal extended
super-BMS algebra, which possesses non-linear correction in the
anti-commutators of supercharges. We present the supersymmetric energy bound
and derive the explicit form of the asymptotic Killing spinors. We also find
the most generic circular symmetric ground state of the theory, which
corresponds to a non-supersymmetric cosmological solutions and derive their
entropy.Comment: 29+1 pages, typos correcte
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