3,426 research outputs found
General Kerr-NUT-AdS Metrics in All Dimensions
The Kerr-AdS metric in dimension D has cohomogeneity [D/2]; the metric
components depend on the radial coordinate r and [D/2] latitude variables \mu_i
that are subject to the constraint \sum_i \mu_i^2=1. We find a coordinate
reparameterisation in which the \mu_i variables are replaced by [D/2]-1
unconstrained coordinates y_\alpha, and having the remarkable property that the
Kerr-AdS metric becomes diagonal in the coordinate differentials dy_\alpha. The
coordinates r and y_\alpha now appear in a very symmetrical way in the metric,
leading to an immediate generalisation in which we can introduce [D/2]-1 NUT
parameters. We find that (D-5)/2 are non-trivial in odd dimensions, whilst
(D-2)/2 are non-trivial in even dimensions. This gives the most general
Kerr-NUT-AdS metric in dimensions. We find that in all dimensions D\ge4
there exist discrete symmetries that involve inverting a rotation parameter
through the AdS radius. These symmetries imply that Kerr-NUT-AdS metrics with
over-rotating parameters are equivalent to under-rotating metrics. We also
consider the BPS limit of the Kerr-NUT-AdS metrics, and thereby obtain, in odd
dimensions and after Euclideanisation, new families of Einstein-Sasaki metrics.Comment: Latex, 24 pages, minor typos correcte
Yang-Mills-Chern-Simons Supergravity
N=(1,0) supergravity in six dimensions admits AdS_3\times S^3 as a vacuum
solution. We extend our recent results presented in hep-th/0212323, by
obtaining the complete N=4 Yang-Mills-Chern-Simons supergravity in D=3, up to
quartic fermion terms, by S^3 group manifold reduction of the six dimensional
theory. The SU(2) gauge fields have Yang-Mills kinetic terms as well as
topological Chern-Simons mass terms. There is in addition a triplet of matter
vectors. After diagonalisation, these fields describe two triplets of
topologically-massive vector fields of opposite helicities. The model also
contains six scalars, described by a GL(3,R)/SO(3) sigma model. It provides the
first example of a three-dimensional gauged supergravity that can obtained by a
consistent reduction of string-theory or M-theory and that admits AdS_3 as a
vacuum solution. There are unusual features in the reduction from
six-dimensional supergravity, owing to the self-duality condition on the 3-form
field. The structure of the full equations of motion in N=(1,0) supergravity in
D=6 is also elucidated, and the role of the self-dual field strength as torsion
is exhibited.Comment: Latex, 22 pages, hep-th number correcte
Killing Spinors for the Bosonic String
We obtain the effective action for the bosonic string with arbitrary
Yang-Mills fields, up to the \alpha' order, in general dimensions. The form of
the action is determined by the requirement that the action admit well-defined
Killing spinor equations, whose projected integrability conditions give rise to
the full set of equations of motion. The success of the construction suggests
that the hidden "pseudo-supersymmetry" associated with the Killing spinor
equations may be a property of the bosonic string itself.Comment: 9 page
Pseudo-Killing Spinors, Pseudo-supersymmetric p-branes, Bubbling and Less-bubbling AdS Spaces
We consider Einstein gravity coupled to an n-form field strength in D
dimensions. Such a theory cannot be supersymmetrized in general, we
nevertheless propose a pseudo-Killing spinor equation and show that the AdS X
Sphere vacua have the maximum number of pseudo-Killing spinors, and hence are
fully pseudo-supersymmetric. We show that extremal p-branes and their
intersecting configurations preserve fractions of the pseudo-supersymmetry. We
study the integrability condition for general (D,n) and obtain the additional
constraints that are required so that the existence of the pseudo-Killing
spinors implies the Einstein equations of motion. We obtain new
pseudo-supersymmetric bubbling AdS_5 X S^5 spaces that are supported by a
non-self-dual 5-form. This demonstrates that non-supersymmegtric conformal
field theories may also have bubbling states of arbitrary droplets of free
fermions in the phase space. We also obtain an example of less-bubbling AdS
geometry in D=8, whose bubbling effects are severely restricted by the
additional constraint arising from the integrability condition.Comment: typos corrected, extra comments and references added, version
appeared in JHE
Lambda and Anti-Lambda Hypernuclei in Relativistic Mean-field Theory
Several aspects about -hypernuclei in the relativistic mean field
theory, including the effective -nucleon coupling strengths based on
the successful effective nucleon-nucleon interaction PK1, hypernuclear magnetic
moment and -hypernuclei, have been presented. The effect of tensor
coupling in -hypernuclei and the impurity effect of to
nuclear structure have been discussed in detail.Comment: 8 pages, 2 figures, Proceedings of the Sendai International Symposium
"Strangeness in Nuclear and Hadronic Systems SENDAI08
Cosmological solutions, p-branes and the Wheeler-DeWitt equation
The low energy effective actions which arise from string theory or M-theory
are considered in the cosmological context, where the graviton, dilaton and
antisymmetric tensor field strengths depend only on time. We show that previous
results can be extended to include cosmological solutions that are related to
the E_N Toda equations. The solutions of the Wheeler-DeWitt equation in
minisuperspace are obtained for some of the simpler cosmological models by
introducing intertwining operators that generate canonical transformations
which map the theories into free theories. We study the cosmological properties
of these solutions, and also briefly discuss generalised Brans-Dicke models in
our framework. The cosmological models are closely related to p-brane solitons,
which we discuss in the context of the E_N Toda equations. We give the explicit
solutions for extremal multi-charge (D-3)-branes in the truncated system
described by the D_4 =O(4,4) Toda equations.Comment: 11 pages (2-column), Revte
From p-branes to Cosmology
We study the relationship between static p-brane solitons and cosmological
solutions of string theory or M-theory. We discuss two different ways in which
extremal p-branes can be generalised to non-extremal ones, and show how wide
classes of recently discussed cosmological models can be mapped into
non-extremal p-brane solutions of one of these two kinds. We also extend
previous discussions of cosmological solutions to include some that make use of
cosmological-type terms in the effective action that can arise from the
generalised dimensional reduction of string theory or M-theory.Comment: Latex, 24 pages, no figur
Gauged Six-dimensional Supergravity from Massive Type IIA
We obtain the complete non-linear Kaluza-Klein ansatz for the reduction of
the bosonic sector of massive type IIA supergravity to the Romans F(4) gauged
supergravity in six dimensions. The latter arises as a consistent warped S^4
reduction.Comment: Latex, 7 page
Fibre Bundles and Generalised Dimensional Reduction
We study some geometrical and topological aspects of the generalised
dimensional reduction of supergravities in D=11 and D=10 dimensions, which give
rise to massive theories in lower dimensions. In these reductions, a global
symmetry is used in order to allow some of the fields to have a non-trivial
dependence on the compactifying coordinates. Global consistency in the internal
space imposes topological restrictions on the parameters of the
compactification as well as the structure of the space itself. Examples that we
consider include the generalised reduction of the type IIA and type IIB
theories on a circle, and also the massive ten-dimensional theory obtained by
the generalised reduction of D=11 supergravity.Comment: 23 pages, Late
f(R) Gravities, Killing Spinor Equations, "BPS" Domain Walls and Cosmology
We derive the condition on f(R) gravities that admit Killing spinor equations
and construct explicit such examples. The Killing spinor equations can be used
to reduce the fourth-order differential equations of motion to the first order
for both the domain wall and FLRW cosmological solutions. We obtain exact "BPS"
domain walls that describe the smooth Randall-Sundrum II, AdS wormholes and the
RG flow from IR to UV. We also obtain exact smooth cosmological solutions that
describe the evolution from an inflationary starting point with a larger
cosmological constant to an ever-expanding universe with a smaller cosmological
constant. In addition, We find exact smooth solutions of pre-big bang models,
bouncing or crunching universes. An important feature is that the scalar
curvature R of all these metrics is varying rather than a constant. Another
intriguing feature is that there are two different f(R) gravities that give
rise to the same "BPS" solution. We also study linearized f(R) gravities in
(A)dS vacua.Comment: 37 pages, discussion on gravity trapping in RSII modified, typos
corrected, further comments and references added; version to appear in JHE
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