9,221 research outputs found
Gyrating Schrodinger Geometries and Non-Relativistic Field Theories
We propose homogeneous metrics of Petrov type III that describe gyrating
Schrodinger geometries as duals to some non-relativistic field theories, in
which the Schrodinger symmetry is broken further so that the phase space has a
linear dependence of the momentum in a selected direction. We show that such
solutions can arise in four-dimensional Einstein-Weyl supergravity as well as
higher-dimensional extended gravities with quadratic curvature terms coupled to
a massive vector. In Einstein-Weyl supergravity, the gyrating Schrodinger
solutions can be supersymmetric, preserving 1/4 of the supersymmetry. We obtain
the exact Green function in the phase space associated with a bulk free massive
scalar.Comment: 9 page
On Realisations of W Algebras
It has been known for some time that algebras can be realised in terms of
an energy-momentum tensor together with additional free scalar fields. Some
recent results have shown that more general realisations are also possible. In
this paper, we consider a wide class of realisations that may be obtained from
the Miura transformation, related to the existence of canonical subalgebras of
the Lie algebras on which the algebras are based. We give explicit formulae
for all realisations of this kind, and discuss their applications in -string
theory.Comment: 11 page
T-duality and U-duality in toroidally-compactified strings
We address the issue of T-duality and U-duality symmetries in the
toroidally-compactified type IIA string. It is customary to take as a starting
point the dimensionally-reduced maximal supergravity theories, with certain
field strengths dualised such that the classical theory exhibits a global
symmetry, where n=11-D in D dimensions. A discrete subgroup then
becomes the conjectured U-duality group. In dimensions D\le 6, these necessary
dualisations include NS-NS fields, whose potentials, rather than merely their
field strengths, appear explicitly in the couplings to the string worldsheet.
Thus the usually-stated U-duality symmetries act non-locally on the fundamental
fields of perturbative string theory. At least at the perturbative level, it
seems to be more appropriate to consider the symmetries of the versions of the
lower-dimensional supergravities in which no dualisations of NS-NS fields are
required, although dualisations of the R-R fields are permissible since these
couple to the string through their field strengths. Taking this viewpoint, the
usual T-duality groups survive unscathed, as one would hope since T-duality is
a perturbative symmetry, but the U-duality groups are modified in D\le 6.Comment: Latex, 21 pages. References and discussion adde
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