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

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

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

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

The Frailty of Economic Reforms: Political Logic and Constitutional Lessons

Why are efficiency-enhancing reforms often frail and subject to being undermined over time? Two theories are examined: public-choice theory, which explains this as the possible result of a need, from time to time, to wipe the slate clean in order to retain productivity in the distribution of favors to interest groups, and a theory which acknowledges that politicians may implement reforms for ideological reasons but still, as time passes, be influenced by the logic of the political and media systems to abandon their initial aspirations. In any case, the demise of reforms is partly a function of the constitutional setting: rules which encourage shortsightedness and easy satisfaction of interest-group agendas make it difficult for decision-makers to withstand pressure for legislative change. Avenues to mitigate these problems through constitutional reforms are explored.tax reform; political incentives; constitutional reform

Time for behavioral political economy? An analysis of articles in behavioral economics

This study analyzes leading research in behavioral economics to see whether it contains advocacy of paternalism and whether it addresses the potential cognitive limitations and biases of the policymakers who are going to implement paternalist policies. The findings reveal that 20.7% of the studied articles in behavioral economics propose paternalist policy action and that 95.5% of these do not contain any analysis of the cognitive ability of policymakers. This suggests that behavioral political economy, in which the analytical tools of behavioral economics are applied to political decision-makers as well, would offer a useful extension of the research program.Behavioral economics; Anomalies; Rationality; Homo economicus; Public choice