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 $j^5_\mu$ in vector like theories like QCD.Comment: 10 pages, Late

Regularized overlap and the chiral determinant

We study the relationship between the continuum overlap and its corresponding chiral determinant, showing that the former amounts to an unregularised version of the latter. We then construct a regularised continuum overlap, and consider the chiral anomalies that follow therefrom. The relation between these anomalies and the ones derived from the formal (i.e., unregularised) overlap is elucidated.Comment: 14 pages, late

Gauge Fields, Fermions and Mass Gaps in 6D Brane Worlds

We study fluctuations about axisymmetric warped brane solutions in 6D minimal gauged supergravity. Much of our analysis is general and could be applied to other scenarios. We focus on bulk sectors that could give rise to Standard Model gauge fields and charged matter. We reduce the dynamics to Schroedinger type equations plus physical boundary conditions, and obtain exact solutions for the Kaluza-Klein wave functions and discrete mass spectra. The power-law warping, as opposed to exponential in 5D, means that zero mode wave functions can be peaked on negative tension branes, but only at the price of localizing the whole Kaluza-Klein tower there. However, remarkably, the codimension two defects allow the Kaluza-Klein mass gap to remain finite even in the infinite volume limit. In principle, not only gravity, but Standard Model fields could `feel' the extent of large extra dimensions, and still be described by an effective 4D theory.Comment: 33 pages, 2 figures; typesetting problem fixed ({\o}replaced by \omega

Fermion zero-modes on brane-worlds

We study localization of bulk fermions on a brane with inclusion of Yang-Mills and scalar backgrounds in higher dimensions and give the conditions under which localized chiral fermions can be obtained.Comment: Latex, 5 pages. A factor "2" mistake that propagated through a number of equations is corrected. Conclusions unchange

The Renormalization Group for Flag Manifolds

The renormalization group equations for a class of non--relativistic quantum $\sigma$--models targeted on flag manifolds are given. These models emerge in a continuum limit of generalized Heisenberg antiferromagnets. The case of the ${SU(3)\over U(1)\times U(1)}$ manifold is studied in greater detail. We show that at zero temperature there is a fixed point of the RG transformations in $(2+\varepsilon )$--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

A Formalism to Analyze the Spectrum of Brane World Scenarios

In this paper we develop a formalism to analyze the spectrum of small perturbations about arbitrary solutions of Einstein, Yang-Mills and scalar systems. We consider a general system of gravitational, gauge and scalar fields in a $D-$dimensional space-time and give the bilinear action for the fluctuations of the fields in the system around an arbitrary solution of the classical field equations. We then consider warped geometries, popular in brane world scenarios, and use the light cone gauge to separate the bilinear action into a totally decoupled spin-two, -one and -zero fluctuations. We apply our general scheme to several examples and discuss in particular localization of abelian and non-abelian gauge fields of the standard model to branes generated by scalar fields. We show in particular that the Nielsen-Olsen string solution gives rise to a normalizable localized spin-1 field in any number of dimensions.Comment: Latex, 31 pages. Final version appeared in Nucl. Phy

Type IIB string theory on AdS_5 X T^{nn'}

We study \kk spectrum of type IIB string theory compactified on $AdS_5 \times T^{nn'}$ in the context of $AdS/CFT$ 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 $d=4$ 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 $R$ charge in the boundary conformal theory are also rational. Furthermore the modes in the bottom of the towers originating from $q$ forms on $T^{11}$ can be put in correspondence with the BRS cohomology classes of the $c=1$ non critical string theory with ghost number $q$. However, a more detailed investigation is called for, to clarify further the relation of this supergravity background with the $c=1$ strings.Comment: Plain Tex, 12 pages, (v2) minor typos corrected, version to appear in PLB. (v3) Problem in the format of titlepage fixe