172 research outputs found
Instanton Effects in Three-Dimensional Supersymmetric Gauge Theories with Matter
Using standard field theory techniques we compute perturbative and instanton
contributions to the Coulomb branch of three-dimensional supersymmetric QCD
with N=2 and N=4 supersymmetry and gauge group SU(2). For the N=4 theory with
one massless flavor, we confirm the proposal of Seiberg and Witten that the
Coulomb branch is the double-cover of the centered moduli space of two BPS
monopoles constructed by Atiyah and Hitchin. Introducing a hypermultiplet mass
term, we show that the asymptotic metric on the Coulomb branch coincides with
the metric on Dancer's deformation of the monopole moduli space. For the N=2
theory with flavors, we compute the one-loop corrections to the metric
and complex structure on the Coulomb branch. We then determine the
superpotential including one-loop effects around the instanton background.
These calculations provide an explicit check of several results previously
obtained by symmetry and holomorphy arguments.Comment: 24 pages, Late
Covariant Quantisation in the Antifield Formalism
In this thesis we give an overview of the antifield formalism and show how it
must be used to quantise arbitrary gauge theories. The formalism is further
developed and illustrated in several examples, including Yang-Mills theory,
chiral and gravity, strings in curved backgrounds and
topological field theories. All these models are characterised by their gauge
algebra, which can be open, reducible, or even infinitly reducible. We show in
detail how to perform the gauge fixing and how to compute the anomalies using
Pauli-Villars regularisation and the heat kernel method. Finally, we discuss
the geometrical structure of the antifield formalism.Comment: Latex, 151 pages, PhD thesis, KUleuven, December 1995 12 files
compressed into thes.tar.g
Superconformal hypermultiplets
We present theories of N=2 hypermultiplets in four spacetime dimensions that are invariant under rigid or local superconformal symmetries. The target spaces of theories with rigid superconformal invariance are (4n)-dimensional {\it special} hyper-K\"ahler manifolds. Such manifolds can be described as cones over tri-Sasakian metrics and are locally the product of a flat four-dimensional space and a quaternionic manifold. The latter manifolds appear in the coupling of hypermultiplets to N=2 supergravity. We employ local sections of an Sp bundle in the formulation of the Lagrangian and transformation rules, thus allowing for arbitrary coordinatizations of the hyper-K\"ahler and quaternionic manifolds
Redefining B-twisted topological sigma models
A recently proposed variation on the usual procedure to perform the
topological B-twist in rigid models is applied to the case of the model on a K\"ahler manifold. This leads to an alternative description of
Witten's topological model, which allows for a proper BRST
interpretation and ghost number assignement. We also show that the auxiliary
fields, which are responsible for the off shell closure of the algebra,
play an important role in our construction.Comment: one reference adde
Instanton Solutions for the Universal Hypermultiplet
We expand our previous analysis on fivebrane and membrane instanton solutions
in the universal hypermultiplet, including near-extremal multi-centered
solutions and mixed fivebrane-membrane charged instantons. The results are most
conveniently described in terms of a double-tensor multiplet.Comment: Minor changes, clarification added. Contribution to the proceedings
of the 36th International Symposium Ahrenshoop, August 200
The Batalin-Vilkovisky Formalism on Fermionic Kaehler Manifolds
We show that the Kaehler structure can be naturally incorporated in the Batalin-Vilkovisky formalism. The phase space of the BV formalism becomes a fermionic Kaehler manifold. By introducing an isometry we explicitly construct the fermionic irreducible hermitian symmetric space. We then give some solutions of the master equation in the BV formalism
Ultracold Superstrings in atomic boson-fermion mixtures
We propose a setup with ultracold atomic gases that can be used to make a
nonrelativistic superstring in four spacetime dimensions. In particular, we
consider for the creation of the superstring a fermionic atomic gas that is
trapped in the core of a vortex in a Bose-Einstein condensate. We explain the
required tuning of experimental parameters to achieve supersymmetry between the
fermionic atoms and the bosonic modes describing the oscillations in the vortex
position. Furthermore, we discuss the experimental consequences of
supersymmetry.Comment: 4 pages, 4 figures; published versio
Order parameter fluctuations in the holographic superconductor
We investigate the effect of order parameter fluctuations in the holographic
superconductor. In particular, using a fully backreacted bulk geometry, the
intrinsic spectral functions of the order parameter in both the normal and the
superconducting phase are computed. We also present a vector-like large-
version of the Ginzburg-Landau model that accurately describes our
long-wavelength results in both phases. The large- limit of the latter model
explains why the Higgs mode and the second-sound mode are not present in the
spectral functions. Our results indicate that the holographic superconductor
describes a relativistic multi-component superfluid in the universal regime of
the BEC-BCS crossover.Comment: 21 pages, 15 figures; version accepted for publicatio
Construction of topological field theories using BV
We discuss in detail the construction of topological field theories using the
Batalin--Vilkovisky (BV) quantisation scheme. By carefully examining the
dependence of the antibracket on an external metric, we show that
differentiating with respect to the metric and the BRST charge do not commute
in general. We introduce the energy momentum tensor in this scheme and show
that it is BRST invariant, both for the classical and quantum BRST operators.
It is antifield dependent, guaranteeing gauge independence. For topological
field theories, this energy momentum has to be quantum BRST exact. This leads
to conditions at each order in . As an example of this procedure, we
consider topological Yang--Mills theory. We show how the reducible set of
symmetries used in topological Yang--Mills can be recovered by means of trivial
systems and canonical transformations. Self duality of the antighosts is
properly treated by introducing an infinite tower of auxiliary fields. Finally,
it is shown that the full energy momentum tensor is classically BRST exact in
the antibracket sense.Comment: 15
Membrane and fivebrane instantons from quaternionic geometry
We determine the one-instanton corrections to the universal hypermultiplet moduli space coming both from Euclidean membranes and NS-fivebranes wrapping the cycles of a (rigid) Calabi-Yau threefold. These corrections are completely encoded by a single function characterizing a generic four-dimensional quaternion-Kahler metric without isometries. We give explicit solutions for this function describing all one-instanton corrections, including the fluctuations around the instanton to all orders in the string coupling constant. In the semi-classical limit these results are in perfect agreement with previous supergravity calculations
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