395 research outputs found
Consistent and covriant anomalies in the overlap formulation of chiral gauge theories
In this letter we show how the covariant anomaly emerges in the overlap
scheme. We also prove that the overlap scheme correctly reproduces the anomaly
in the flavour currents such as in vector like theories like QCD.Comment: 10 pages, Late
The Renormalization Group for Flag Manifolds
The renormalization group equations for a class of non--relativistic quantum
--models targeted on flag manifolds are given. These models emerge in a
continuum limit of generalized Heisenberg antiferromagnets. The case of the
manifold is studied in greater detail. We show
that at zero temperature there is a fixed point of the RG transformations in
--dimensions where the theory becomes relativistic. We study
the linearized RG transformations in the vicinity of this fixed point and show
that half of the couplings are irrelevant. We also show that at this fixed
point there is an enlargement of the global isometries of the target manifold.
We construct a discrete non--abelian enlargement of this kind.Comment: 22 page
Non-linear quantum mechanics and semi-classical field theories
Imperial Users onl
Type IIB string theory on AdS_5 X T^{nn'}
We study \kk spectrum of type IIB string theory compactified on in the context of correspondence. We examine some of the
modes of the complexified 2 form potential as an example and show that for the
states at the bottom of the \kk tower the corresponding boundary field
operators have rational conformal dimensions. The masses of some of the
fermionic modes in the bottom of each tower as functions of the charge in
the boundary conformal theory are also rational. Furthermore the modes in the
bottom of the towers originating from forms on can be put in
correspondence with the BRS cohomology classes of the non critical string
theory with ghost number . However, a more detailed investigation is called
for, to clarify further the relation of this supergravity background with the
strings.Comment: Plain Tex, 12 pages, (v2) minor typos corrected, version to appear in
PLB. (v3) Problem in the format of titlepage fixe
Nonsingular 4d-flat branes in six-dimensional supergravities
We show that six-dimensional supergravity models admit nonsingular solutions
in the presence of flat three-brane sources with positive tensions. The models
studied in this paper are nonlinear sigma models with the target spaces of the
scalar fields being noncompact manifolds. For the particular solutions of the
scalar field equations which we consider, only two brane sources are possible
which are positioned at those points where the scalar field densities diverge,
without creating a divergence in the Ricci scalar or the total energy. These
solutions are locally invariant under 1/2 of D=6 supersymmetries, which,
however, do not integrate to global Killing spinors. Other branes can be
introduced by hand by allowing for local deficit angles in the transverse space
without generating any kind of curvature singularities.Comment: 13 pages. The discussion of modular invariance is amended and a
reference has been adde
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