60 research outputs found
Genus four superstring measures
A main issue in superstring theory are the superstring measures. D'Hoker and
Phong showed that for genus two these reduce to measures on the moduli space of
curves which are determined by modular forms of weight eight and the bosonic
measure. They also suggested a generalisation to higher genus. We showed that
their approach works, with a minor modification, in genus three and we
announced a positive result also in genus four. Here we give the modular form
in genus four explicitly. Recently S. Grushevsky published this result as part
of a more general approach.Comment: 7 pages. To appear in Letters in Mathematical Physic
Cosmological solutions from fake N=2 EYM supergravity
We characterise the (fake) supersymmetric solutions of Wick-rotated N=2 d=4
gauged supergravity coupled to non-Abelian vector multiplets. In the time-like
case we obtain generalisations of Kastor & Traschen's cosmological black holes:
they have a specific time-dependence and the base-space must be 3-dimensional
hyperCR/Gauduchon-Tod space. In the null-case, we find that the metric has a
holonomy contained in Sim(2), give a general characterisation of the solutions,
and give some examples. Finally, we point out that in some cases the solutions
we found are non-BPS solutions to N=2 d=4 supergravity coupled to vector
multiplets.Comment: 30 pages. Comments and references added, typos correcte
General Supersymmetric Solutions of Five-Dimensional Supergravity
The classification of 1/4-supersymmetric solutions of five dimensional gauged
supergravity coupled to arbitrary many abelian vector multiplets, which was
initiated in hep-th/0401129, is completed. The structure of all solutions for
which the Killing vector constructed from the Killing spinor is null is
investigated in both the gauged and the ungauged theories and some new
solutions are constructed.Comment: 24 pages, references added, uses JHEP3.cl
The vanishing of two-point functions for three-loop superstring scattering amplitudes
In this paper we show that the two-point function for the three-loop chiral
superstring measure ansatz proposed by Cacciatori, Dalla Piazza, and van Geemen
vanishes. Our proof uses the reformulation of ansatz in terms of even cosets,
theta functions, and specifically the theory of the linear system
on Jacobians introduced by van Geemen and van der Geer.
At the two-loop level, where the amplitudes were computed by D'Hoker and
Phong, we give a new proof of the vanishing of the two-point function (which
was proven by them). We also discuss the possible approaches to proving the
vanishing of the two-point function for the proposed ansatz in higher genera
Characterization of all the supersymmetric solutions of gauged N=1,d=5 supergravity
We find a complete characterization of all the supersymmetric solutions of
non-Abelian gauged N=1,d=5 supergravity coupled to vector multiplets and
hypermultiplets: the generic forms of the metrics as functions of the scalars
and vector fields plus the equations that all these must satisfy. These
equations are now a complicated non-linear system and there it seems impossible
to produce an algorithm to construct systematically all supersymmetric
solutions.Comment: Some references and two comments adde
New supersymmetric solutions of N=2, D=5 gauged supergravity with hyperscalars
We construct new supersymmetric solutions, including AdS bubbles, in an N=2
truncation of five-dimensional N=8 gauged supergravity. This particular
truncation is given by N=2 gauged supergravity coupled to two vector multiples
and three incomplete hypermultiplets, and was originally investigated in the
context of obtaining regular AdS bubble geometries with multiple active
R-charges. We focus on cohomogeneity-one solutions corresponding to objects
with two equal angular momenta and up to three independent R-charges.
Curiously, we find a new set of zero and negative mass solitons asymptotic to
AdS_5/Z_k, for k \ge 3, which are everywhere regular without closed timelike
curves.Comment: Latex 3 times, 42 page
Flow Equations for Non-BPS Extremal Black Holes
We exploit some common features of black hole and domain wall solutions of
(super)gravity theories coupled to scalar fields and construct a class of
stable extremal black holes that are non-BPS, but still can be described by
first-order differential equations. These are driven by a "superpotential'',
which replaces the central charge Z in the usual black hole potential. We
provide a general procedure for finding this class and deriving the associated
"superpotential''. We also identify some other cases which do not belong to
this class, but show a similar behaviour.Comment: LaTeX, 21 pages, 2 figures. v2: reference added, JHEP versio
All timelike supersymmetric solutions of N=2, D=4 gauged supergravity coupled to abelian vector multiplets
The timelike supersymmetric solutions of N=2, D=4 gauged supergravity coupled
to an arbitrary number of abelian vector multiplets are classified using
spinorial geometry techniques. We show that the generalized holonomy group for
vacua preserving N supersymmetries is GL((8-N)/2,C) N/2 C^((8-N)/2)
GL(8,R), where N=0,2,4,6,8. The spacetime turns out to be a
fibration over a three-dimensional base manifold with U(1) holonomy and
nontrivial torsion. Our results can be used to construct new supersymmetric AdS
black holes with nontrivial scalar fields turned on.Comment: 35 pages, uses JHEP3.cl
The supersymmetric solutions and extensions of ungauged matter-coupled N=1,d=4 supergravity
We find the most general supersymmetric solutions of ungauged N=1,d=4
supergravity coupled to an arbitrary number of vector and chiral
supermultiplets, which turn out to be essentially pp-waves and strings. We also
introduce magnetic 1-forms and their supersymmetry transformations and 2-forms
associated to the isometries of the scalar manifold and their supersymmetry
transformations. Only the latter can couple to BPS objects (strings), in
agreement with our results.Comment: Some misprints and citations correcte
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