1,149 research outputs found
The Dirac field in Taub-NUT background
We investigate the SO(4,1) gauge-invariant theory of the Dirac fermions in
the external field of the Kaluza-Klein monopole, pointing out that the quantum
modes can be recovered from a Klein-Gordon equation analogous to the Schr\"
odinger equation in the Taub-NUT background. Moreover, we show that there is a
large collection of observables that can be directly derived from those of the
scalar theory. These offer many possibilities of choosing complete sets of
commuting operators which determine the quantum modes. In addition there are
some spin- like and Dirac-type operators involving the covariantly constant
Killing-Yano tensors of the hyper-K\" ahler Taub-NUT space. The energy
eigenspinors of the central modes in spherical coordinates are completely
evaluated in explicit, closed form.Comment: 20 pages, latex, no figure
Quantum Metamorphosis of Conformal Transformation in D3-Brane Yang-Mills Theory
We show how the linear special conformal transformation in four-dimensional
N=4 super Yang-Mills theory is metamorphosed into the nonlinear and
field-dependent transformation for the collective coordinates of Dirichlet
3-branes, which agrees with the transformation law for the space-time
coordinates in the anti-de Sitter (AdS) space-time. Our result provides a new
and strong support for the conjectured relation between AdS supergravity and
super conformal Yang-Mills theory (SYM). Furthermore, our work sheds
elucidating light on the nature of the AdS/SYM correspondence.Comment: 8 pages, no figure
A Superstring Theory in Four Curved Space-Time Dimensions
Neveu-Schwarz-Ramond type heterotic and type-II superstrings in four
dimensional curved space-time are constructed as exact superconformal
theories. The tachyon is eliminated with a GSO projection. The theory is based
on the N=1 superconformal gauged WZW model for the anti-de Sitter coset
with integer central extension . The model has dynamical
duality properties in its space-time metric that are similar to the large-small
() duality of tori. To first order in a expansion we
give expressions for the metric, the dilaton, the Ricci tensor and their dual
generalizations. The curvature scalar has several singularities at various
locations in the 4-dimensional manifold. This provides a new singular solution
to Einstein's equations in the presence of matter in four dimensions. A
non-trivial path integral measure which we conjectured in previous work for
gauged WZW models is verified.Comment: 12 page
string model in curved spacetime and exact conformal results
Pursuing further the recent methods in the algebraic Hamiltonian approach to
gauged WZW models, we apply them to the bosonic SL(2,R) X SU(2)/R^2 model
recently investigated by Nappi and Witten. We find the global space and compute
the conformally exact metric and dilaton fields to all orders in the
expansion. The semiclassical limit of our exact results agree
with the lowest order perturbation computation which was done in the Lagrangian
formalism. We also discuss the supersymmetric type-II and heterotic versions of
this model and verify the non-renormalization of .Comment: USC-92/HEP-B3, 13 pages and 1 figur
Effective action of magnetic monopole in three-dimensional electrodynamics with massless matter and gauge theories of superconductivity
We compute one-loop effective action of magnetic monopole in
three-dimensional electrodynamics of massless bosons and fermions and find that
it contains an infrared logarithm. So, when the number of massless matter
species is sufficiently large, monopoles are suppressed and in the weak
coupling limit charged particles are unconfined. This result provides some
support to gauge theories of high-temperature superconductors. It also provides
a mechanism by which interlayer tunneling of excitations with one unit of the
ordinary electric charge can be suppressed while that of a doubly charged
object is allowed.Comment: 8 pages, LATEX, UCLA/93/TEP/41 (the last sentence of the paragraph
concerning applications at the end of the paper has been deleted; mailing
problems have been corrected
Lie superalgebras and irreducibility of A_1^(1)-modules at the critical level
We introduce the infinite-dimensional Lie superalgebra and
construct a family of mappings from certain category of -modules
to the category of A_1^(1)-modules of critical level. Using this approach, we
prove the irreducibility of a family of A_1^(1)-modules at the critical level.
As a consequence, we present a new proof of irreducibility of certain
Wakimoto modules. We also give a natural realizations of irreducible quotients
of relaxed Verma modules and calculate characters of these representations.Comment: 21 pages, Late
No N=4 Strings on Wolf Spaces
We generalize the standard supersymmetric Kazama-Suzuki coset
construction to the case by requiring the {\it non-linear}
(Goddard-Schwimmer) quasi-superconformal algebra to be realized on
cosets. The constraints that we find allow very simple geometrical
interpretation and have the Wolf spaces as their natural solutions. Our results
obtained by using components-level superconformal field theory methods are
fully consistent with standard results about supersymmetric
two-dimensional non-linear sigma-models and WZNW models on Wolf spaces.
We construct the actions for the latter and express the quaternionic structure,
appearing in the coset solution, in terms of the symplectic structure
associated with the underlying Freudenthal triple system. Next, we gauge the
QSCA and build a quantum BRST charge for the string propagating on
a Wolf space. Surprisingly, the BRST charge nilpotency conditions rule out the
non-trivial Wolf spaces as consistent string backgrounds.Comment: 31 pages, LaTeX, special macros are include
Wave functions and correlation functions for GKP strings from integrability
We develop a general method of computing the contribution of the vertex
operators to the semi-classical correlation functions of heavy string states,
based on the state-operator correspondence and the integrable structure of the
system. Our method requires only the knowledge of the local behavior of the
saddle point configuration around each vertex insertion point and can be
applied to cases where the precise forms of the vertex operators are not known.
As an important application, we compute the contributions of the vertex
operators to the three-point functions of the large spin limit of the
Gubser-Klebanov-Polyakov (GKP) strings in spacetime, left unevaluated
in our previous work [arXiv:1110.3949] which initiated such a study. Combining
with the finite part of the action already computed previously and with the
newly evaluated divergent part of the action, we obtain finite three-point
functions with the expected dependence of the target space boundary coordinates
on the dilatation charge and the spin.Comment: 80 pages, 7 figures, v2: typos and minor errors corrected, a
reference added, v3: typos and a reference corrected, published versio
Current-Current Deformations of Conformal Field Theories, and WZW Models
Moduli spaces of conformal field theories corresponding to current-current
deformations are discussed. For WZW models, CFT and sigma model considerations
are compared. It is shown that current-current deformed WZW models have
WZW-like sigma model descriptions with non-bi-invariant metrics, additional
B-fields and a non-trivial dilaton.Comment: 30 pages, latex, v2: remarks and references adde
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