1,837 research outputs found
Duality Symmetric Strings, Dilatons and O(d,d) Effective Actions
We calculate the background field equations for the T-duality symmetric
string building on previous work by including the effect of the Dilaton up to
two-loops. Inclusion of the Dilaton allows us to obtain the full beta
functionals of the duality symmetric sigma model. We are able to interpret the
result in terms of a dimensionally reduced O(d,d) invariant target space
effective action.Comment: 15 pages, latex; v2 reference added, typos fixe
Background Field Equations for the Duality Symmetric String
This paper describes the background field equations for strings in T-duality
symmetric formalisms in which the dimension of target space is doubled and the
sigma model supplemented with constraints. These are calculated by demanding
the vanishing of the beta-functional of the sigma model couplings in the
doubled target space. We demonstrate the equivalence with the background field
equations of the standard string sigma model.Comment: 26 pages, latex, v2 typos correcte
Connecting T-duality invariant theories
We show that the vanishing of the one-loop beta-functional of the doubled
formalism (which describes string theory on a torus fibration in which the
fibres are doubled) is the same as the equation of motion of the recently
proposed generalised metric formulation of double field theory restricted to
this background: both are the vanishing of a generalised Ricci tensor. That
this tensor arises in both backgrounds indicates the importance of a new
doubled differential geometry for understanding both constructions.Comment: 25 pages. v2: published version with minor correction
Gravitational and Schwinger model anomalies: how far can the analogy go?
We describe the most general treatment of all anomalies both for chiral and
massless Dirac fermions, in two-dimensional gravity. It is shown that for this
purpose two regularization dependent parameters are present in the effective
action. Analogy to the \sc\ model is displayed corresponding to a specific
choice of the second parameter, thus showing that the gravitational model
contains \a\ relations having no analogy in the \sc\ model.Comment: 16 pages, no figure, phyzzx macro, square.tex has been deleted from
the previous versio
A Double Sigma Model for Double Field Theory
We define a sigma model with doubled target space and calculate its
background field equations. These coincide with generalised metric equation of
motion of double field theory, thus the double field theory is the effective
field theory for the sigma model.Comment: 26 pages, v1: 37 pages, v2: references added, v3: updated to match
published version - background and detail of calculations substantially
condensed, motivation expanded, refs added, results unchange
Duality Invariant M-theory: Gauged supergravities and Scherk-Schwarz reductions
We consider the reduction of the duality invariant approach to M-theory by a
U-duality group valued Scherk-Schwarz twist. The result is to produce
potentials for gauged supergravities that are normally associated with
non-geometric compactifications. The local symmetry reduces to gauge
transformations with the gaugings exactly matching those of the embedding
tensor approach to gauged supergravity. Importantly, this approach now includes
a nontrivial dependence of the fields on the extra coordinates of the extended
space.Comment: 22 pages Latex; v2: typos corrected and references adde
Duality orbits of non-geometric fluxes
Compactifications in duality covariant constructions such as generalised
geometry and double field theory have proven to be suitable frameworks to
reproduce gauged supergravities containing non-geometric fluxes. However, it is
a priori unclear whether these approaches only provide a reformulation of old
results, or also contain new physics. To address this question, we classify the
T- and U-duality orbits of gaugings of (half-)maximal supergravities in
dimensions seven and higher. It turns out that all orbits have a geometric
supergravity origin in the maximal case, while there are non-geometric orbits
in the half-maximal case. We show how the latter are obtained from
compactifications of double field theory.Comment: 39 pages, 1 figure, 6 tables; v2: refs added, published versio
Heterotic string from a higher dimensional perspective
The (abelian bosonic) heterotic string effective action, equations of motion
and Bianchi identity at order alpha prime in ten dimensions, are shown to be
equivalent to a higher dimensional action, its derived equations of motion and
Bianchi identity. The two actions are the same up to the gauge fields: the
latter are absorbed in the higher dimensional fields and geometry. This
construction is inspired by heterotic T-duality, which becomes natural in this
higher dimensional theory. We also prove the equivalence of the heterotic
string supersymmetry conditions with higher dimensional geometric conditions.
Finally, some known Kahler and non-Kahler heterotic solutions are shown to be
trivially related from this higher dimensional perspective, via a simple
exchange of directions. This exchange can be encoded in a heterotic T-duality,
and it may also lead to new solutions.Comment: 43 pages; minor changes; version published in NP
Massive Type II in Double Field Theory
We provide an extension of the recently constructed double field theory
formulation of the low-energy limits of type II strings, in which the RR fields
can depend simultaneously on the 10-dimensional space-time coordinates and
linearly on the dual winding coordinates. For the special case that only the RR
one-form of type IIA carries such a dependence, we obtain the massive
deformation of type IIA supergravity due to Romans. For T-dual configurations
we obtain a `massive' but non-covariant formulation of type IIB, in which the
10-dimensional diffeomorphism symmetry is deformed by the mass parameter.Comment: 21 page
- …