1,182 research outputs found
Massive Three-Dimensional Supergravity From R+R^2 Action in Six Dimensions
We obtain a three-parameter family of massive N=1 supergravities in three
dimensions from the 3-sphere reduction of an off-shell N=(1,0) six-dimensional
Poincare supergravity that includes a curvature squared invariant. The
three-dimensional theory contains an off-shell supergravity multiplet and an
on-shell scalar matter multiplet. We then generalise this in three dimensions
to an eight-parameter family of supergravities. We also find a duality
relationship between the six-dimensional theory and the N=(1,0) six-dimensional
theory obtained through a T^4 reduction of the heterotic string effective
action that includes the higher-order terms associated with the
supersymmetrisation of the anomaly-cancelling \tr(R\wedge R) term.Comment: Latex, 32 Pages, an equation is corrected, a few new equations and a
number of clarifying remarks are adde
On the new massive gravity and AdS/CFT
Demanding the existence of a simple holographic -theorem, it is shown that
a general (parity preserving) theory of gravity in 2+1 dimensions involving
upto four derivative curvature invariants reduces to the new massive gravity
theory. We consider extending the theory including upto six derivative
curvature invariants. Black hole solutions are presented and consistency with
1+1 CFTs is checked. We present evidence that bulk unitarity is still in
conflict with a positive CFT central charge for generic choice of parameters.
However, for a special choice of parameters appearing in the four and six
derivative terms reduces the linearized equations to be two derivative, thereby
ameliorating the unitarity problem.Comment: 16 pages, 2 figures. v4: typo correcte
A boundary stress tensor for higher-derivative gravity in AdS and Lifshitz backgrounds
We investigate the Brown-York stress tensor for curvature-squared theories.
This requires a generalized Gibbons-Hawking term in order to establish a
well-posed variational principle, which is achieved in a universal way by
reducing the number of derivatives through the introduction of an auxiliary
tensor field. We examine the boundary stress tensor thus defined for the
special case of `massive gravity' in three dimensions, which augments the
Einstein-Hilbert term by a particular curvature-squared term. It is shown that
one obtains finite results for physical parameters on AdS upon adding a
`boundary cosmological constant' as a counterterm, which vanishes at the
so-called chiral point. We derive known and new results, like the value of the
central charges or the mass of black hole solutions, thereby confirming our
prescription for the computation of the stress tensor. Finally, we inspect
recently constructed Lifshitz vacua and a new black hole solution that is
asymptotically Lifshitz, and we propose a novel and covariant counterterm for
this case.Comment: 25 pages, 1 figure; v2: minor corrections, references added, to
appear in JHE
Warped black holes in 3D general massive gravity
We study regular spacelike warped black holes in the three dimensional
general massive gravity model, which contains both the gravitational
Chern-Simons term and the linear combination of curvature squared terms
characterizing the new massive gravity besides the Einstein-Hilbert term. The
parameters of the metric are found by solving a quartic equation constrained by
an inequality that imposes the absence of closed timelike curves. Explicit
expressions for the central charges are suggested by exploiting the fact that
these black holes are discrete quotients of spacelike warped AdS(3) and a known
formula for the entropy. Previous results obtained separately in topological
massive gravity and in new massive gravity are recovered as special cases.Comment: 38 pages, 7 figures. v2: minor changes, added refs and an appendix on
self-dual and null z-warped black hole
AdS Black Hole Solutions in the Extended New Massive Gravity
We have obtained (warped) AdS black hole solutions in the three dimensional
extended new massive gravity. We investigate some properties of black holes and
obtain central charges of the two dimensional dual CFT. To obtain the central
charges, we use the relation between entropy and temperature according to the
AdS/CFT dictionary. For AdS black holes, one can also use the central charge
function formalism which leads to the same results.Comment: 24pages, some organization corrected, minor corrections, references
added, final published versio
The California-Kepler survey. X. The radius gap as a function of stellar mass, metallicity, and age
In 2017, the California-Kepler Survey (CKS) published its first data release (DR1) of high-resolution optical spectra of 1305 planet hosts. Refined CKS planet radii revealed that small planets are bifurcated into two distinct populations, super-Earths (smaller than 1.5 Râ) and sub-Neptunes (between 2.0 and 4.0 Râ), with few planets in between (the "radius gap"). Several theoretical models of the radius gap predict variation with stellar mass, but testing these predictions is challenging with CKS DR1 due to its limited Mâ range of 0.8â1.4 Mâ. Here we present CKS DR2 with 411 additional spectra and derived properties focusing on stars of 0.5â0.8 Mâ. We found that the radius gap follows Rp â Pm with m = â0.10 ± 0.03, consistent with predictions of X-ray and ultraviolet- and core-powered mass-loss mechanisms. We found no evidence that m varies with Mâ. We observed a correlation between the average sub-Neptune size and Mâ. Over 0.5â1.4 Mâ, the average sub-Neptune grows from 2.1 to 2.6 Râ, following with α = 0.25 ± 0.03. In contrast, there is no detectable change for super-Earths. These MââRp trends suggest that protoplanetary disks can efficiently produce cores up to a threshold mass of Mc, which grows linearly with stellar mass according to Mc â 10 Mâ(Mâ/Mâ). There is no significant correlation between sub-Neptune size and stellar metallicity (over â0.5 to +0.5 dex), suggesting a weak relationship between planet envelope opacity and stellar metallicity. Finally, there is no significant variation in sub-Neptune size with stellar age (over 1â10 Gyr), which suggests that the majority of envelope contraction concludes after âŒ1 Gyr
Status of the Planet Formation Imager (PFI) concept
This is the author accepted manuscript. The final version is available from SPIE via the DOI in this record.The Planet Formation Imager (PFI) project aims to image the period of planet assembly directly, resolving
structures as small as a giant planetâs Hill sphere. These images will be required in order to determine the key
mechanisms for planet formation at the time when processes of grain growth, protoplanet assembly, magnetic
fields, disk/planet dynamical interactions and complex radiative transfer all interact â making some planetary
systems habitable and others inhospitable. We will present the overall vision for the PFI concept, focusing
on the key technologies and requirements that are needed to achieve the science goals. Based on these key
requirements, we will define a cost envelope range for the design and highlight where the largest uncertainties
lie at this conceptual stage
Status of the Planet Formation Imager (PFI) concept
The Planet Formation Imager (PFI) project aims to image the period of planet assembly directly, resolving structures as small as a giant planetâs Hill sphere. These images will be required in order to determine the key mechanisms for planet formation at the time when processes of grain growth, protoplanet assembly, magnetic fields, disk/planet dynamical interactions and complex radiative transfer all interact â making some planetary systems habitable and others inhospitable. We will present the overall vision for the PFI concept, focusing on the key technologies and requirements that are needed to achieve the science goals. Based on these key requirements, we will define a cost envelope range for the design and highlight where the largest uncertainties lie at this conceptual stage.This is the author accepted manuscript. The final version is available from SPIE via http://dx.doi.org/10.1117/12.223392
Holographic Renormalization and Stress Tensors in New Massive Gravity
We obtain holographically renormalized boundary stress tensors with the
emphasis on a special point in the parameter space of three dimensional new
massive gravity, using the so-called Fefferman-Graham coordinates with relevant
counter terms. Through the linearized equations of motion with a standard
prescription, we also obtain correlators among these stress tensors. We argue
that the self-consistency of holographic renormalization determines counter
terms up to unphysical ambiguities. Using these renormalized stress tensors in
Fefferman-Graham coordinates, we obtain the central charges of dual CFT, and
mass and angular momentum of some black hole solutions. These results are
consistent with the previous ones obtained by other methods. In this study on
the Fefferman-Graham expansion of new massive gravity, some aspects of higher
curvature gravity are revealed.Comment: Version accepted for publication in JHEP, conclusion revised,
references adde
Short-cut to new anomalies in gravity duals to logarithmic conformal field theories
Various massive gravity theories in three dimensions are conjecturally dual
to logarithmic conformal field theories (LCFTs). We summarise the status of
these conjectures. LCFTs are characterised by the values of the central charges
and the so-called "new anomalies". We employ a short-cut to calculate these new
anomalies in generalised massive gravity and in the recently proposed
higher-derivative gravity theories with holographic c-theorem. Both cases
permit LCFTs exhibiting intriguing features, like rank three Jordan cells or
non-zero central charges. Finally, as an example we discuss in some detail the
partially massless version of new massive gravity, a theory with several
special properties that we call "partially massless gravity".Comment: 34 pages, 2 figures; v2: added references; v3: Several rewordings in
the introduction and section 2, added references. Matches published versio
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