4,905 research outputs found
KT and HKT Geometries in Strings and in Black Hole Moduli Spaces
Some selected applications of KT and HKT geometries in string theory,
supergravity, black hole moduli spaces and hermitian geometry are reviewed. It
is shown that the moduli spaces of a large class of five-dimensional
supersymmetric black holes are HKT spaces. In hermitian geometry, it is shown
that a compact, conformally balanced, strong KT manifold whose associated KT
connection has holonomy contained in SU(n) is Calabi-Yau. The implication of
this result in the context of some string compactifications is explained.Comment: 26 pages, Contribution to the Proceedings of the Bonn workshop on
"Special Geometric Structures in String Theory", a change in terminology and
some other minor change
New potentials for conformal mechanics
We find under some mild assumptions that the most general potential of
1-dimensional conformal systems with time independent couplings is expressed as
, where is a homogeneous function with respect to a homothetic
motion in configuration space and is determined from an equation with
source a homothetic potential. Such systems admit at most an SL(2,\bR)
conformal symmetry which, depending on the couplings, is embedded in Diff(R)SL(2,\bR)V=\alpha
x^2+\beta x^{-2}\alpha\betaSL(2,\bR)AdS_2 x S^3AdS_2 x S^3 x S^3AdS_2/CFT_1$.Comment: 15 pages, significant changes, references adde
Seeking the balance: Patching double and exceptional field theories
We investigate the patching of double and exceptional field theories. In
double field theory the patching conditions imposed on the spacetime after
solving the strong section condition imply that the 3-form field strength
is exact. A similar conclusion can be reached for the form field strengths of
exceptional field theories after some plausive assumptions are made on the
relation between the transition functions of the additional coordinates and the
patching data of the form field strengths. We illustrate the issues that arise,
and explore several alternative options which include the introduction of
C-folds and of the topological geometrisation condition.Comment: substantial changes, section with example added, to appear in jhep,
24 page
The Universality of M-branes
We review the evidence for the various dualities amongst the five D=10
superstring theories and for the existence of M-theory using the associated
effective supergravity theories. We also summarise the combinatorial technics
developed for constructing BPS solutions in D=11 supergravity theory and
conjecture that all the BPS solutions of D<11 supergravity theories can be
derived from the BPS solutions of D=11 supergravity that preserve 1/2 the
supersymmetry. To demonstrate this, we derive the dyonic p-brane solutions from
eleven dimensions.Comment: Many changes have been made in the text and some references have been
added. 8 pages, Latex, Talk at the Imperial College Workshop 5-10 Jul
Brane Surgery with Thom Classes
We propose a method to investigate the conservation of brane charges at the
intersection of two or more branes using the Thom classes of their normal
bundles. In particular we find a relation between the charge of the branes
involved in the configuration and the charge of the defects on the branes due
to the intersection. We also explore the applications of our method for various
brane intersections in type II strings and M-theory.Comment: 20 pages, Phyzz
The Solutions of Affine and Conformal Affine Toda Field Theories
We give new formulations of the solutions of the field equations of the
affine Toda and conformal affine Toda theories on a cylinder and
two-dimensional Minkowski space-time. These solutions are parameterised in
terms of initial data and the resulting covariant phase spaces are
diffeomorphic to the Hamiltonian ones. We derive the fundamental Poisson
brackets of the parameters of the solutions and give the general static
solutions for the affine theory.Comment: 11pp, phyzz
Grassmannians,Calibrations and Five-Brane Intersections
We present a geometric construction of a new class of hyper-Kahler manifolds
with torsion. This involves the superposition of the four-dimensional
hyper-Kahler geometry with torsion associated with the NS-5-brane along
quaternionic planes in quaternionic k-space, \bH^k. We find the moduli space
of these geometries and show that it can be constructed using the bundle space
of the canonical quaternionic line bundle over a quaternionic projective space.
We also investigate several special cases which are associated with certain
classes of quaternionic planes in \bH^k. We then show that the
eight-dimensional geometries we have found can be constructed using
quaternionic calibrations. We generalize our construction to superpose the same
four-dimensional hyper-Kahler geometry with torsion along complex planes in
\bC^{2k}. We find that the resulting geometry is Kahler with torsion. The
moduli space of these geometries is also investigated. In addition, the
applications of these new geometries to M-theory and sigma models are
presented. In particular, we find new solutions of IIA supergravity with the
interpretation of intersecting NS-5-branes at Sp(2)-angles on a string and show
that they preserve 3/32, 1/8, 5/32 and 3/16 of supersymmetry. We also show that
two-dimensional sigma models with target spaces the above manifolds have (p,q)
extended supersymmetry.Comment: 39 pages, phyzzx; a previously undetermined fraction of supersymmetry
has now been fixed; a table has been replaced; version submitted for
publication in CM
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