The heterotic prepotential from eleven dimensions

We compactify M-theory in the Horava-Witten formulation on S^1/Z_2 \times K3 \times T^2. Focusing on the moduli-space of vector multiplets of the resulting four-dimensional N=2 theory, we determine the prepotential as an expansion in two dimensionless parameters which both scale as \kappa^{2/3}. We determine the prepotential completely to relative order \kappa^{4/3} and compare the expression with the results obtained for the perturbative string theories. We find complete agreement to relative order \kappa^{4/3} between the strong and weak coupling regimes. The sources of higher order perturbative and non-perturbative corrections to the prepotential are also briefly discussed from the M-theory perspective.Comment: 19 pages, LaTeX; minor change

(Super)conformal many-body quantum mechanics with extended supersymmetry

We study N=4 supersymmetric quantum-mechanical many-body systems with M bosonic and 4M fermionic degrees of freedom. We also investigate the further restrictions of conformal and superconformal invariance. In particular, we construct conformal N=4 extensions of the A_{M-1} Calogero models, which for generic values of the coupling constant are not SU(1,1|2) superconformal. This class of models is also extended to arbitrary (even) N. We give both hamiltonian and (classical) lagrangean formulations. In the latter case we use both component and N=4 superfield formulations.Comment: 16 pages, LaTeX2e; minor corrections, references adde

Generalized Toda Theories from WZNW Reduction

We reconsider the, by Brink and Vasiliev, recently proposed generalized Toda field theories using the framework of WZNW$\rightarrow$Toda reduction. The reduced theory has a gauge symmetry which can be fixed in various ways. We discuss some different gauge choices. In particular we study the ${\cal W}$ algebra associated with the generalized model in some different realizations, corresponding to different gauge choices. We also investigate the mapping between the Toda field and a free field and show the relation between the ${\cal W}$ algebra generators expressed in terms of the two different fields. All results apply also to the case of ordinary Toda theories.Comment: 18 pages, Plain LaTe

Derivative corrections to the D-brane Born-Infeld action: non-geodesic embeddings and the Seiberg-Witten map

We dimensionally reduce the four-derivative corrections to the parity-conserving part of the D9-brane effective action involving all orders of the gauge field, to obtain corrections to the actions for the lower-dimensional Dp-branes. These corrections involve the second fundamental form and correspond to a non-geodesic embedding of the Dp-brane into (flat) ten-dimensional space. In addition, we study the transformation of the corrections under the Seiberg-Witten map relating the ordinary and non-commutative theories. A speculative discussion about the higher-order terms in the derivative expansion is also included.Comment: 20 pages, LaTeX. v2: relation between (2.11) and result in hep-th/9903210 clarified. v3: minor changes; reference adde

A note on S-duality for the N=1* Sp(2n) and SO(2n+1) super-Yang-Mills theories

We study the N=1* supersymmetric gauge theories with gauge groups Sp(2n) and SO(2n+1). These theories are obtained from the corresponding N=4 supersymmetric Yang-Mills theories via a mass deformation. We show that the number of quantum vacua in the Sp(2n) theory is equal to the number of quantum vacua in the SO(2n+1) theory. This constitutes non-trivial support for S-duality between these theories. The verification of the equality of the number of quantum vacua involves a rather esoteric identity due to Ramanujan.Comment: 9 pages. v2:clarifying footnote adde

Towards a manifestly SL(2,Z)-covariant action for the type IIB (p,q) super-five-branes

We determine a manifestly SL(2,Z)-covariant kappa-symmetric action for the type IIB (p,q) five-branes as a perturbative expansion in the world-volume field strengths within the framework where the brane tension is generated by a world-volume field. In this formulation the Lagrangian is expected to be polynomial; we construct the kappa-invariant action to fourth order in the world-volume field strengths.Comment: 9 pages, LaTeX2

Towards relating the kappa-symmetric and pure-spinor versions of the supermembrane

We study the relation between the kappa-symmetric formulation of the supermembrane in eleven dimensions and the pure-spinor version. Recently, Berkovits related the Green-Schwarz and pure-spinor superstrings. In this paper, we attempt to extend this method to the supermembrane. We show that it is possible to reinstate the reparameterisation constraints in the pure-spinor formulation of the supermembrane by introducing a topological sector and performing a similarity transformation. The resulting BRST charge is then of conventional type and is argued to be (related to) the BRST charge of the kappa-symmetric supermembrane in a formulation where all second class constraints are 'gauge unfixed' to first class constraints. In our analysis we also encounter a natural candidate for a (non-covariant) supermembrane analogue of the superstring b ghost.Comment: 15 Page

An A_r threesome: Matrix models, 2d CFTs and 4d N=2 gauge theories

We explore the connections between three classes of theories: A_r quiver matrix models, d=2 conformal A_r Toda field theories and d=4 N=2 supersymmetric conformal A_r quiver gauge theories. In particular, we analyse the quiver matrix models recently introduced by Dijkgraaf and Vafa and make detailed comparisons with the corresponding quantities in the Toda field theories and the N=2 quiver gauge theories. We also make a speculative proposal for how the matrix models should be modified in order for them to reproduce the instanton partition functions in quiver gauge theories in five dimensions.Comment: 43 pages; v2: minor typos corrected, reference added. v3: Added clarifying discussions in sections 4.1 and 5.1; typos correcte