5 research outputs found
On a gauge invariant description of soliton dynamics
We present important elements of a gauge and diffeomorphism invariant
formulation of the moduli space approximation to soliton dynamics. We argue
that explicit velocity-dependent modifications are determined entirely from
gauge and diffeomorphism invariance. We illustrate the formalism for the case
of a Yang-Mills theory on a curved spacetime background.Comment: 8 pages, contribution to the proceedings of the 35th Ahrenshoop
Symposium, 200
Stationary Configurations and Geodesic Description of Supersymmetric Black Holes
This thesis contains a detailed study of various properties of
supersymmetric black holes. In chapter I an overview over some of the
fascinating aspects of black hole physics is provided. In particular, the
string theory approach to black hole entropy is discussed. One of the
consequences of the string theory results is that black hole entropy can
be understood within the context of an effective field theory only if one
resorts to supergravity theories with higher-order curvature interactions.
To this extent, some relevant elements of N=2 supersymmetric theories and
supergravity theories are introduced in chapter II. In chapter III N=2
supergravity theories with higher-order curvature interactions are
described. Chapter IV contains a classification of the fully
supersymmetric vacua and a characterization of a large class of stationary
BPS black hole configurations in the presence of higher-derivative
interactions. In chapter V the derivation of the macroscopic entropy
formula appropriate for theories with higher-order curvature interactions
is reviewed and compared to the results of string theory. Furthermore, in
the absence of higher-order curvature interactions, the metric on the
moduli space of simple multi-centered black hole solutions is calculated.
In chapter VI, finally, a formalism to derive the geodesic description of
generic gravitational solitons is developed
Black hole partition functions and duality
The macroscopic entropy and the attractor equations for BPS black holes in
four-dimensional N=2 supergravity theories follow from a variational principle
for a certain `entropy function'. We present this function in the presence of
R^2-interactions and non-holomorphic corrections. The variational principle
identifies the entropy as a Legendre transform and this motivates the
definition of various partition functions corresponding to different ensembles
and a hierarchy of corresponding duality invariant inverse Laplace integral
representations for the microscopic degeneracies. Whenever the microscopic
degeneracies are known the partition functions can be evaluated directly. This
is the case for N=4 heterotic CHL black holes, where we demonstrate that the
partition functions are consistent with the results obtained on the macroscopic
side for black holes that have a non-vanishing classical area. In this way we
confirm the presence of a measure in the duality invariant inverse Laplace
integrals. Most, but not all, of these results are obtained in the context of
semiclassical approximations. For black holes whose area vanishes classically,
there remain discrepancies at the semiclassical level and beyond, the nature of
which is not fully understood at present.Comment: 36 pages, Late
A note on topological amplitudes in hybrid string theory
We study four-dimensional compactifications of type II superstrings on Calabi-Yau spaces using the formalism of hybrid string theory. Chiral and twisted-chiral interactions are rederived, which involve the coupling of the compactification moduli to two powers of the Weyl-tensor and of the derivative of the universal tensor field-strength