383 research outputs found
Supersymmetric Drinfeld-Sokolov reduction
The Drinfeld-Sokolov construction of integrable hierarchies, as well as its
generalizations, may be extended to the case of loop superalgebras. A
sufficient condition on the algebraic data for the resulting hierarchy to be
invariant under supersymmetry transformation is given. The method used is a
construction of the hierarchies in superspace, where supersymmetry is manifest.
Several examples are discussed.Comment: 25 pages, LaTeX fil
N=2 KP and KdV hierarchies in extended superspace
We give the formulation in extended superspace of an supersymmetric KP
hierarchy using chirality preserving pseudo-differential operators. We obtain
two quadratic hamiltonian structures, which lead to different reductions of the
KP hierarchy. In particular we find two different hierarchies with the
classical super- algebra as a hamiltonian structure. The relation
with the formulation in superspace is carried out.Comment: 18 pages, LaTeX file, important reference adde
Stable non-BPS D-branes of type I
We review the boundary state description of the non-BPS D-branes in the type
I string theory and show that the only stable configurations are the D-particle
and the D-instanton. We also compute the gauge and gravitational interactions
of the non-BPS D-particles and compare them with the interactions of the dual
non-BPS particles of the heterotic string finding complete agreement. In this
way we provide further dynamical evidence of the heterotic/type I duality.Comment: 8 pages, 1 figure.eps, JHEP.cls, talk given by A. Lerda at the TMR
Conference "Quantum aspects of gauge theories, supersymmetry and
unification", Paris, September 199
Modular anomaly equation, heat kernel and S-duality in N=2 theories
We investigate epsilon-deformed N=2 superconformal gauge theories in four
dimensions, focusing on the N=2* and Nf=4 SU(2) cases. We show how the modular
anomaly equation obeyed by the deformed prepotential can be efficiently used to
derive its non-perturbative expression starting from the perturbative one. We
also show that the modular anomaly equation implies that S-duality is
implemented by means of an exact Fourier transform even for arbitrary values of
the deformation parameters, and then we argue that it is possible,
perturbatively in the deformation, to choose appropriate variables such that it
reduces to a Legendre transform.Comment: 30 pages, LeTeX2e. V2: references added, appendix B expanded, a few
typos correcte
Transformations of locally conformally K\"ahler manifolds
We consider several transformation groups of a locally conformally K\"ahler
manifold and discuss their inter-relations. Among other results, we prove that
all conformal vector fields on a compact Vaisman manifold which is neither
locally conformally hyperk\"ahler nor a diagonal Hopf manifold are Killing,
holomorphic and that all affine vector fields with respect to the minimal Weyl
connection of a locally conformally K\"ahler manifold which is neither
Weyl-reducible nor locally conformally hyperk\"ahler are holomorphic and
conformalComment: 8 page
Higher dimensional abelian Chern-Simons theories and their link invariants
The role played by Deligne-Beilinson cohomology in establishing the relation
between Chern-Simons theory and link invariants in dimensions higher than three
is investigated. Deligne-Beilinson cohomology classes provide a natural abelian
Chern-Simons action, non trivial only in dimensions , whose parameter
is quantized. The generalized Wilson -loops are observables of the
theory and their charges are quantized. The Chern-Simons action is then used to
compute invariants for links of -loops, first on closed
-manifolds through a novel geometric computation, then on
through an unconventional field theoretic computation.Comment: 40 page
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