Intersecting D-branes, Chern-kernels and the inflow mechanism

We analyse a system of arbitrarily intersecting D-branes in ten-dimensional supergravity. Chiral anomalies are supported on the intersection branes, called I-branes. For non-transversal intersections anomaly cancellation has been realized until now only cohomologically but not locally, due to short-distance singularities. In this paper we present a consistent local cancellation mechanism, writing the delta-like brane currents as differentials of the recently introduced Chern--kernels, J=dK. In particular, for the first time we achieve anomaly cancellation for dual pairs of D-branes. The Chern-kernel approach allows to construct an effective action for the RR-fields which is free from singularities and cancels the quantum anomalies on all D-branes and I-branes.Comment: 1+28 pages, no figures. References update

Quantum properties of the heterotic five-brane

We find that the conjectured heterotic SO(32) five-brane sigma model develops necessarily k-anomalies, and we investigate their form. We show that these anomalies can be absorbed by modifications of the superspace constraints, that satisfy automatically the modified Bianchi-identity $dH_7=X_8$ of N=1, D=10 supergravity. The k-anomalies induce in particular a quantum deformation of the torsion constraint $T_{\alpha\beta}^a=2\gamma_{\alpha\beta}^a$.Comment: 15 pages, no figure

Dynamics of self-interacting strings and energy-momentum conservation

Classical strings coupled to a metric, a dilaton and an axion, as conceived by superstring theory, suffer from ultraviolet divergences due to self-interactions. Consequently, as in the case of radiating charged particles, the corresponding effective string dynamics cannot be derived from an action principle. We propose a fundamental principle to build this dynamics, based on local energymomentum conservation in terms of a well-defined distribution-valued energy-momentum tensor. Its continuity equation implies a finite equation of motion for self-interacting strings. The construction is carried out explicitly for strings in uniform motion in arbitrary space\u2013time dimensions, where we establish cancelations of ultraviolet divergences which parallel superstring non-renormalization theorems. The uniqueness properties of the resulting dynamics are analyzed

Deformations of quantum field theories and integrable models

Deformations of quantum field theories which preserve Poincar\'e covariance and localization in wedges are a novel tool in the analysis and construction of model theories. Here a general scenario for such deformations is discussed, and an infinite class of explicit examples is constructed on the Borchers-Uhlmann algebra underlying Wightman quantum field theory. These deformations exist independently of the space-time dimension, and contain the recently studied warped convolution deformation as a special case. In the special case of two-dimensional Minkowski space, they can be used to deform free field theories to integrable models with non-trivial S-matrix.Comment: 36 pages, no figures: Minor changes and corrections in Section 3. Added new Section 5 on von Neumann algebraic formulation, and modular structur

A Quantum field theory of dyons

We construct a classical field theory action which upon quantization via the functional integral approach, gives rise to a consistent Dirac-string independent quantum field theory. The approach entails a systematic derivation of the correlators of all gauge invariant observables, and also of charged dyonic fields. Manifest SO(2)-duality invariance and Lorentz invariance are ensured by the PST-approach.Comment: 9 pages, LaTeX, talk given at the conference "Quantum aspects of gauge theories, supersymmetry and unification", Paris, September 199

World-manifold and target space anomalies in heterotic Green-Schwarz strings and five-branes

The quantum consistency of sigma-models describing the dynamics of extended objects in a curved background requires the cancellation of their world-volume anomalies, which are conformal anomalies for the heterotic string and $SO(1,5)$ Lorentz-anomalies for the heterotic five-brane, and of their ten dimensional target space anomalies. In determining these anomalies in a $D=10$ Lorentz-covariant back-ground gauge we find that for the heterotic string the worldvolume anomalies cancel for 32 heterotic fermions while for the conjectured heterotic five-brane they cancel for only 16 heterotic fermions, this result being in contrast with the string/five-brane duality conjecture. For what concerns the target space anomalies we find that the five-brane eight-form Lorentz-anomaly polynomial differs by a factor of $1/2$ from what is expected on the basis of duality. Possible implications of these results are discussed.Comment: 9 pages, no figures, talk given at the Conference "Gauge Theories, Applied Supersymmetry and Quantum Gravity", London, July 199

Urban CGE Modeling: An Introduction

Cities are usually confronted with a large variety of economic development choices. With growing environmental concern as well as rising income and wealth inequalities, assessment of the impacts of such choices is likely to gain in importance. Consequently, the demand for adequate assessment tools will grow. Computable general equilibrium (CGE) models analyze issues of resource allocation and income distribution in market economies. They have become a widely accepted tool for policy assessment over the past two decades but are currently still primarily a field for specialists. This is particularly distinctive in the case of urban CGE models, which are the focus of this paper.

Modular nuclearity: A generally covariant perspective

A quantum field theory in its algebraic description may admit many irregular states. So far, selection criteria to distinguish physically reasonable states have been restricted to free fields (Hadamard condition) or to flat spacetimes (e.g. Buchholz-Wichmann nuclearity). We propose instead to use a modular l^p-condition, which is an extension of a strengthened modular nuclearity condition to generally covariant theories. The modular nuclearity condition was previously introduced in Minkowski space, where it played an important role in constructive two dimensional algebraic QFT's. We show that our generally covariant extension of this condition makes sense for a vast range of theories, and that it behaves well under causal propagation and taking mixtures. In addition we show that our modular l^p-condition holds for every quasi-free Hadamard state of a free scalar quantum field (regardless of mass or scalar curvature coupling). However, our condition is not equivalent to the Hadamard condition.Comment: 42 page