53 research outputs found
The Topology of Double Field Theory
We describe the doubled space of Double Field Theory as a group manifold
with an arbitrary generalized metric. Local information from the latter is not
relevant to our discussion and so only captures the topology of the doubled
space. Strong Constraint solutions are maximal isotropic submanifold in
. We construct them and their Generalized Geometry in Double Field Theory on
Group Manifolds. In general, admits different physical subspace which
are Poisson-Lie T-dual to each other. By studying two examples, we reproduce
the topology changes induced by T-duality with non-trivial -flux which were
discussed by Bouwknegt, Evslin and Mathai [hep-th/0306062].Comment: 37 pages, 1 figure, published versio
Consistent Compactification of Double Field Theory on Non-geometric Flux Backgrounds
In this paper, we construct non-trivial solutions to the -dimensional
field equations of Double Field Theory (DFT) by using a consistent
Scherk-Schwarz ansatz. The ansatz identifies internal directions with
a twist which is directly connected to the covariant fluxes
. It exhibits linear independent generalized
Killing vectors and gives rise to a gauged supergravity in
dimensions. We analyze the covariant fluxes and the corresponding gauged
supergravity with a Minkowski vacuum. We calculate fluctuations around such
vacua and show how they gives rise to massive scalars field and vectors field
with a non-abelian gauge algebra. Because DFT is a background independent
theory, these fields should directly correspond the string excitations in the
corresponding background. For we perform a complete scan of all
allowed covariant fluxes and find two different kinds of backgrounds: the
single and the double elliptic case. The later is not T-dual to a geometric
background and cannot be transformed to a geometric setting by a field
redefinition either. While this background fulfills the strong constraint, it
is still consistent with the Killing vectors depending on the coordinates and
the winding coordinates, thereby giving a non-geometric patching. This
background can therefore not be described in Supergravity or Generalized
Geometry.Comment: 44 pages, 3 tables, references added, typos correcte
On Inflation and de Sitter in Non-Geometric String Backgrounds
We study the problem of obtaining de Sitter and inflationary vacua from
dimensional reduction of double field theory (DFT) on nongeometric string
backgrounds. In this context, we consider a new class of effective potentials
that admit Minkowski and de Sitter minima. We then construct a simple model of
chaotic inflation arising from T-fold backgrounds and we discuss the
possibility of trans-Planckian field range from nongeometric monodromies as
well as the conditions required to get slow roll.Comment: 21 pages, 2 figures, references added, typos corrected, note adde
Double Field Theory on Group Manifolds (Thesis)
This thesis deals with Double Field Theory (DFT), an effective field theory
capturing the low energy dynamics of closed strings on a torus. It renders
T-duality on a torus manifest by adding winding coordinates in addition to
the space time coordinates. An essential consistency constraint of the
theory, the strong constraint, only allows for field configurations which
depend on half of the coordinates of the arising doubled space. I derive
DFT, a generalization of the current formalism. It captures
the low energy dynamics of a closed bosonic string propagating on a compact
group manifold. Its classical action and the corresponding gauge
transformations arise from Closed String Field Theory up to cubic order in the
massless fields. These results are rewritten in terms of a generalized metric
and extended to all orders in the fields. There is an explicit distinction
between background and fluctuations. For the gauge algebra to close, the latter
have to fulfill a modified strong constraint, while for the former the weaker
closure constraint is sufficient. Besides the generalized diffeomorphism
invariance known from the original formulation, DFT is
invariant under standard diffeomorphisms of the doubled space. They are broken
by imposing the totally optional extended strong constraint. In doing so, the
original formulation is restored. A flux formulation for the new theory is
derived and its connection to generalized Scherk-Schwarz compactifications is
discussed. Further, a possible tree-level uplift of a genuinely non-geometric
background (not T-dual to any geometric configuration) is presented. Finally, a
long standing problem, the missing of a prescription to construct the twist in
generalized Scherk-Schwarz compactifications, is solved. Altogether, a more
general picture of DFT and the structures it is based on emerges.Comment: PhD Thesis, 142 pages, 7 figure
Flux Formulation of DFT on Group Manifolds and Generalized Scherk-Schwarz Compactifications
A flux formulation of Double Field Theory on group manifold is derived and
applied to study generalized Scherk-Schwarz compactifications, which give rise
to a bosonic subsector of half-maximal, electrically gauged supergravities. In
contrast to the flux formulation of original DFT, the covariant fluxes split
into a fluctuation and a background part. The latter is connected to a
-dimensional, pseudo Riemannian manifold, which is isomorphic to a Lie
group embedded into O(). All fields and parameters of generalized
diffeomorphisms are supported on this manifold, whose metric is spanned by the
background vielbein GL(). This vielbein takes the role of the
twist in conventional generalized Scherk-Schwarz compactifications. By doing
so, it solves the long standing problem of constructing an appropriate twist
for each solution of the embedding tensor. Using the geometric structure,
absent in original DFT, is identified with the left invariant
Maurer-Cartan form on the group manifold, in the same way as it is done in
geometric Scherk-Schwarz reductions. We show in detail how the Maurer-Cartan
form for semisimple and solvable Lie groups is constructed starting from the
Lie algebra. For all compact embeddings in O(), we calculate .Comment: 40 pages, no figures, minor changes, published versio
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