From N=2 Supergravity to Constrained Moduli Spaces

In this talk we review some results concerning a mechanism for reducing the moduli space of a topological field theory to a proper submanifold of the ordinary moduli space. Such mechanism is explicitly realized in the example of constrained topological gravity, obtained by topologically twisting the N=2 Liouville theory.Comment: (Talk given at the Trieste Workshop on String Theory, April 1994) LaTeX file, 17 pages, SISSA 66/94/EP, IFUM 470/F

Gauge Fields and D-branes

We prove that self-dual gauge fields in type I superstring theory are equivalent to configurations of Dirichlet 5-branes, by showing that the world-sheet theory of a Dirichlet 1-brane moving in a background of 5-branes includes an ``ADHM sigma model.'' This provides an explicit construction of the equivalent self-dual gauge field. We also discuss type II.Comment: harvmac, 9p

Monopole Condensates in Seiberg-Witten Theory

A product of two Riemann surfaces of genuses p_1 and p_2 solves the Seiberg-Witten monopole equations for a constant Weyl spinor that represents a monopole condensate. Self-dual electromagnetic fields require p_1=p_2=p and provide a solution of the euclidean Einstein-Maxwell-Dirac equations with p-1 magnetic vortices in one surface and the same number of electric vortices in the other. The monopole condensate plays the role of cosmological constant. The virtual dimension of the moduli space is zero, showing that for given p_1 and p_2, the solutions are unique.Comment: 10 page

Anticommutativity Equation in Topological Quantum Mechanics

We consider topological quantum mechanics as an example of topological field theory and show that its special properties lead to numerous interesting relations for topological corellators in this theory. We prove that the generating function $\mathcal{F}$ for thus corellators satisfies the anticommutativity equation $(\mathcal{D}- \mathcal{F})^2=0$. We show that the commutativity equation $[dB,dB]=0$ could be considered as a special case of the anticommutativity equation.Comment: 6 pages, no figures, Late

Topological Massive Sigma Models

In this paper we construct topological sigma models which include a potential and are related to twisted massive supersymmetric sigma models. Contrary to a previous construction these models have no central charge and do not require the manifold to admit a Killing vector. We use the topological massive sigma model constructed here to simplify the calculation of the observables. Lastly it is noted that this model can be viewed as interpolating between topological massless sigma models and topological Landau-Ginzburg models.Comment: 20 pages, Phyzzx. Revised version to appear in Nucl. Phys. B. The construction of the model is clarified and there are a few minor change

On mixed phases in gauge theories

In many gauge theories at different values of parameters entering Lagrangian, the vacuum is dominated by coherent condensates of different mutually non-local fields (for instance, by condensates of electric or magnetic charges, or by various dyons). It is argued that the transition between these "dual to each other" phases proceeds through the intermediate "mixed phase", having qualitatively different features. The examples considered include: ordinary YM, N=1 SYM, N=1 SQCD, and broken N=2 SYM and SQCD.Comment: Latex, 19 pages; Talk given at "Continuous Advances in QCD-2002/Arkadyfest", honoring the 60-th birthday of Arkady Vainshtein; 17-23 May 2002, University of Minneapolis, Minnesota, USA; v.3: the extended and improved versio

The Mathai-Quillen Formalism and Topological Field Theory

These lecture notes give an introductory account of an approach to cohomological field theory due to Atiyah and Jeffrey which is based on the construction of Gaussian shaped Thom forms by Mathai and Quillen. Topics covered are: an explanation of the Mathai-Quillen formalism for finite dimensional vector bundles; the definition of regularized Euler numbers of infinite dimensional vector bundles; interpretation of supersymmetric quantum mechanics as the regularized Euler number of loop space; the Atiyah-Jeffrey interpretation of Donaldson theory; the construction of topological gauge theories from infinite dimensional vector bundles over spaces of connections.Comment: 34 a4.sty pages (Notes of lectures given at the Karpacz Winter School on `Infinite Dimensional Geometry in Physics', 17-27 February 1992

Global U(1) R-Symmetry And Conformal Invariance Of (0,2) Models

We derive a condition under which (0,2) linear sigma models possess a ``left-moving'' conformal stress tensor in \bq cohomology (i.e. which leaves invariant the ``right-moving'' ground states) even away from their critical points. At the classical level this enforces quasihomogeneity of the superpotential terms. The persistence of this structure at the quantum level on the worldsheet is obstructed by an anomaly unless the charges and superpotential degrees satisfy a condition which is equivalent to the condition for the cancellation of the anomaly in a particular ``right-moving'' U(1) R-symmetry.Comment: 8 page

G/GG/G--Topological Field Theories by Cosetting GkG_k

$G/G$ topological field theories based on $G_k$ WZW models are constructed and studied. These coset models are formulated as Complex BRST cohomology in $G^c_k$, the complexified level $k$ current algebra. The finite physical spectrum corresponds to the conformal blocks of $G_k$ .The amplitudes for $G/G$ theories are argued to be given in terms of the $G_k$ fusion rules. The $G_k/G_k$ character is the Kac-Weyl numerator of $G_k$ and is interpreted as an index. The Complex BRST cohomology is found to contain states of arbitrary ghost number. Intriguing similarities of $G/G$ to $c\leq 1$ matter systems coupled to two dimensional gravity are pointed out.Comment: 40 pages (52/2 if use the little option of harvmac.tex

Observations on the Topological Structure in 2d Gravity Coupled to Minimal Matter

By using a bosonization we uncover the topological gravity structure of Labastida, Pernici and Witten in ordinary $2d$ gravity coupled to $(p,q)$ minimal models. We study the cohomology class associated with the fermionic charge of the topological gravity which is shown to be isomorphic to that of the total $BRST$ charge. One of the ground ring generators of $c_M <1$ string theory is found to be in the equivariant cohomology of this fermionic charge.Comment: 13 pages, plain tex, UG-5/94 Some clarifying statements and two new references adde