24 research outputs found
Non-relativistic metrics with extremal limits
We present solutions of type IIB supergravity with z=2 Schrodinger
asymptotics that admit an extremal limit, i.e. the black hole horizon has a
double zero. These solutions are obtained as TsT transformations of the charged
planar black hole in AdS_5 \times S^5. Unlike the uncharged solution, the
Ramond-Ramond two-form is turned on. We study the thermodynamic properties of
these new solutions, and we show that the ratio of shear viscosity to entropy
density is 1/4\pi even in the extremal limit. We also consider the
TsT-transformed soliton and show that, for a special radius of the compact
circle, there is a confinement-deconfinement phase transition at zero
temperature between the soliton and black hole phases.Comment: 23 pages, references and clarifications added, typos corrected,
restriction in phase transition due to equation 6.5 emphasized; published
versio
T-Duality For String in Horava-Lifshitz Gravity
We continue our study of the Lorentz breaking string theories. These theories
are defined as string theory with modified Hamiltonian constraint which breaks
the Lorentz symmetry of target space-time. We analyze properties of this theory
in the target space-time that possesses isometry along one direction. We also
derive the T-duality rules for Lorentz breaking string theories and show that
they are the same as that of Buscher's T-duality for the relativistic strings.Comment: 17 pages, references adde
Supersymmetric IIB Solutions with Schr\"{o}dinger Symmetry
We find a class of non-relativistic supersymmetric solutions of IIB
supergravity with non-trivial B-field that have dynamical exponent n=2 and are
invariant under the Schrodinger group. For a general Sasaki-Einstein internal
manifold with U(1)^3 isometry, the solutions have two real supercharges. When
the internal manifold is S^5, the number of supercharges can be four. We also
find a large class of non-relativistic scale invariant type IIB solutions with
dynamical exponents different from two. The explicit solutions and the values
of the dynamical exponents are determined by vector eigenfunctions and
eigenvalues of the Laplacian on an Einstein manifold.Comment: 28 pages, LaTe
The absence of the Kerr black hole in the Ho\v{r}ava-Lifshitz gravity
We show that the Kerr metric does not exist as a fully rotating black hole
solution to the modified Ho\v{r}ava-Lifshitz (HL) gravity with
and case. We perform it by showing that the Kerr metric does not
satisfy full equations derived from the modified HL gravity.Comment: 35 pages, no figure
The Black Hole and Cosmological Solutions in IR modified Horava Gravity
Recently Horava proposed a renormalizable gravity theory in four dimensions
which reduces to Einstein gravity with a non-vanishing cosmological constant in
IR but with improved UV behaviors. Here, I study an IR modification which
breaks "softly" the detailed balance condition in Horava model and allows the
asymptotically flat limit as well. I obtain the black hole and cosmological
solutions for "arbitrary" cosmological constant that represent the analogs of
the standard Schwartzschild-(A)dS solutions which can be asymptotically (A)dS
as well as flat and I discuss some thermodynamical properties. I also obtain
solutions for FRW metric with an arbitrary cosmological constant. I study its
implication to the dark energy and find that it seems to be consistent with
current observational data.Comment: Footnote 5 about the the very meaning of the horizons and Hawking
temperature is added; Accepted in JHE
A note on Friedmann equation of FRW universe in deformed Horava-Lifshitz gravity from entropic force
With entropic interpretation of gravity proposed by Verlinde, we obtain the
Friedmann equation of the Friedmann-Robertson-Walker universe for the deformed
Ho\v{r}ava-Lifshitz gravity. It is shown that, when the parameter of
Ho\v{r}ava-Lifshitz gravity , the modified Friedmann
equation will go back to the one in Einstein gravity. This results may imply
that the entropic interpretation of gravity is effective for the deformed
Ho\v{r}ava-Lifshitz gravity.Comment: 9 pages, no figure
Slowly rotating black holes in the Horava-Lifshitz gravity
We investigate slowly rotating black holes in the Ho\v{r}ava-Lifshitz (HL)
gravity. For and , we find a slowly rotating black
hole of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. We
discuss their thermodynamic properties by computing mass, temperature, angular
momentum, and angular velocity on the horizon.Comment: 12 pages, no figures, version to appear in EPJ
Branes at Quantum Criticality
In this paper we propose new non-relativistic p+1 dimensional theory. This
theory is defined in such a way that the potential term obeys the principle of
detailed balance where the generating action corresponds to p-brane action.
This condition ensures that the norm of the vacuum wave functional of p+1
dimensional theory is equal to the partition function of p-brane theory.Comment: 17 pages, references added, typos fixed,v2. minor change
Caustic avoidance in Horava-Lifshitz gravity
There are at least four versions of Horava-Lishitz gravity in the literature.
We consider the version without the detailed balance condition with the
projectability condition and address one aspect of the theory: avoidance of
caustics for constant time hypersurfaces. We show that there is no caustic with
plane symmetry in the absence of matter source if \lambda\ne 1. If \lambda=1 is
a stable IR fixed point of the renormalization group flow then \lambda is
expected to deviate from 1 near would-be caustics, where the extrinsic
curvature increases and high-energy corrections become important. Therefore,
the absence of caustics with \lambda\ne 1 implies that caustics cannot form
with this symmetry in the absence of matter source. We argue that inclusion of
matter source will not change the conclusion. We also argue that caustics with
codimension higher than one will not form because of repulsive gravity
generated by nonlinear higher curvature terms. These arguments support our
conjecture that there is no caustic for constant time hypersurfaces. Finally,
we discuss implications to the recently proposed scenario of ``dark matter as
integration constant''.Comment: 19 pages; extended to general z \geq 3, typos corrected (v2); version
accepted for publication in JCAP (v3
Horava-Lifshitz f(R) Gravity
This paper is devoted to the construction of new type of f(R) theories of
gravity that are based on the principle of detailed balance. We discuss two
versions of these theories with and without the projectability condition.Comment: 22 pages, references adde