1,738 research outputs found

### Supersymmetry for Gauged Double Field Theory and Generalised Scherk-Schwarz Reductions

Previous constructions of supersymmetry for double field theory have relied
on the so called strong constraint. In this paper, the strong constraint is
relaxed and the theory is shown to possess supersymmetry once the generalised
Scherk-Schwarz reduction is imposed. The equivalence between the generalised
Scherk-Schwarz reduced theory and the gauged double field theory is then
examined in detail for the supersymmetric theory. As a byproduct we write the
generalised Killing spinor equations for the supersymmetric double field
theory.Comment: 29 pages, LateX, v2 typos fixed and some improved discussion, version
as in Journa

### The string partition function in Hull's doubled formalism

T-duality is one of the essential elements of string theory. Recently, Hull
has developed a formalism where the dimension of the target space is doubled so
as to make T-duality manifest. This is then supplemented with a constraint
equation that allows the connection to the usual string sigma model. This paper
analyses the partition function of the doubled formalism by interpreting the
constraint equation as that of a chiral scalar and then using holomorphic
factorisation techniques to determine the partition function. We find there is
quantum equivalence to the ordinary string once the topological interaction
term is included.Comment: 16 pages, latex, v2 typos corrected, v3 some comments adde

### Branes are Waves and Monopoles

In a recent paper it was shown that fundamental strings are null waves in
Double Field Theory. Similarly, membranes are waves in exceptional extended
geometry. Here the story is continued by showing how various branes are
Kaluza-Klein monopoles of these higher dimensional theories. Examining the
specific case of the E7 exceptional extended geometry, we see that all branes
are both waves and monopoles. Along the way we discuss the O(d; d)
transformation of localized brane solutions not associated to an isometry and
how true T-duality emerges in Double Field Theory when the background possesses
isometries.Comment: 32 pages, Latex, v2, typos correcte

### Duality Symmetric String and M-Theory

We review recent developments in duality symmetric string theory. We begin
with the world sheet doubled formalism which describes strings in an extended
space time with extra coordinates conjugate to winding modes. This formalism is
T-duality symmetric and can accommodate non-geometric T-fold backgrounds which
are beyond the scope of Riemannian geometry. Vanishing of the conformal anomaly
of this theory can be interpreted as a set of spacetime equations for the
background fields. These equations follow from an action principle that has
been dubbed Double Field Theory (DFT). We review the aspects of generalised
geometry relevant for DFT. We outline recent extensions of DFT and explain how,
by relaxing the so-called strong constraint with a Scherk Schwarz ansatz, one
can obtain backgrounds that simultaneously depend on both the regular and
T-dual coordinates. This provides a purely geometric higher dimensional origin
to gauged supergravities that arise from non-geometric compactification. We
then turn to M-theory and describe recent progress in formulating an E_{n(n)}
U-duality covariant description of the dynamics. We describe how spacetime may
be extended to accommodate coordinates conjugate to brane wrapping modes and
the construction of generalised metrics in this extend space that unite the
bosonic fields of supergravity into a single object. We review the action
principles for these theories and their novel gauge symmetries. We also
describe how a Scherk Schwarz reduction can be applied in the M-theory context
and the resulting relationship to the embedding tensor formulation of maximal
gauged supergravities.Comment: Review article. 122 pages. V2 Published Version in Physics Report

### The gauge structure of generalised diffeomorphisms

We investigate the generalised diffeomorphisms in M-theory, which are gauge
transformations unifying diffeomorphisms and tensor gauge transformations.
After giving an En(n)-covariant description of the gauge transformations and
their commutators, we show that the gauge algebra is infinitely reducible,
i.e., the tower of ghosts for ghosts is infinite. The Jacobiator of generalised
diffeomorphisms gives such a reducibility transformation. We give a concrete
description of the ghost structure, and demonstrate that the infinite sums give
the correct (regularised) number of degrees of freedom. The ghost towers belong
to the sequences of rep- resentations previously observed appearing in tensor
hierarchies and Borcherds algebras. All calculations rely on the section
condition, which we reformulate as a linear condition on the cotangent
directions. The analysis holds for n < 8. At n = 8, where the dual gravity
field becomes relevant, the natural guess for the gauge parameter and its
reducibility still yields the correct counting of gauge parameters.Comment: 24 pp., plain tex, 1 figure. v2: minor changes, including a few added
ref

### Membranes with a boundary

We investigate the recently developed theory of multiple membranes. In
particular, we consider open membranes, i.e. the theory defined on a membrane
world volume with a boundary. We first restrict our attention to the gauge
sector of the theory. We obtain a boundary action from the Chern-Simons terms.
Secondly, we consider the addition of certain boundary terms to various
Chern-Simons theories coupled to matter. These terms ensure the full bulk plus
boundary action has the correct amount of supersymmetry. For the ABJM model,
this construction motivates the inclusion of a boundary quartic scalar
potential. The boundary dynamics obtained from our modified theory produce
Basu-Harvey type equations describing membranes ending on a fivebrane. The
ultimate goal of this work is to throw light on the theory of fivebranes using
the theory of open membranes.Comment: 48 pages, Latex, v2 references adde

### Confinement and the AdS/CFT Correspondence

We study the thermodynamics of the confined and unconfined phases of
superconformal Yang-Mills in finite volume and at large N using the AdS/CFT
correspondence. We discuss the necessary conditions for a smooth phase
crossover and obtain an N-dependent curve for the phase boundary.Comment: 12 pages, 1 figure, RevTe

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