20,117 research outputs found
Finite Gauge Transformations and Geometry in Double Field Theory
Recently proposed forms for gauge transformations with finite parameters in
double field theory are discussed and problematic issues are identified. A new
form for finite gauge transformations is derived that reveals the underlying
gerbe structure and the close relationship with generalised geometry. The
nature of generalised tensors is elucidated, and in particular it is seen that
the presence of a constant metric with split signature does not restrict the
doubled geometry, provided it is a generalised tensor rather than a
conventional tensor.Comment: 28 page
Non-geometric strings, symplectic gravity and differential geometry of Lie algebroids
Based on the structure of a Lie algebroid for non-geometric fluxes in string
theory, a differential-geometry calculus is developed which combines usual
diffeomorphisms with so-called \beta-diffeomorphisms emanating from gauge
symmetries of the Kalb-Ramond field. This allows to construct a bi-invariant
action of Einstein-Hilbert type comprising a metric, a (quasi-)symplectic
structure \beta and a dilaton. As a salient feature, this symplectic gravity
action and the resulting equations of motion take a form which is similar to
the standard action and field equations. Furthermore, the two actions turn out
to be related via a field redefinition reminiscent of the Seiberg-Witten limit.
Remarkably, this redefinition admits a direct generalization to higher-order
\alpha'-corrections and to the additional fields and couplings appearing in the
effective action of the superstring. Simple solutions to the equations of
motion of the symplectic gravity action, including Calabi-Yau geometries, are
discussed.Comment: 42 pages; v2: published versio
Geometric Lagrangians for massive higher-spin fields
Lagrangians for massive, unconstrained, higher-spin bosons and fermions are
proposed. The idea is to modify the geometric, gauge invariant Lagrangians
describing the corresponding massless theories by the addition of suitable
quadratic polynomials. These polynomials provide generalisations of the
Fierz-Pauli mass term containing all possible traces of the basic field. No
auxiliary fields are needed.Comment: 50 pages, 3 appendices; typos corrected, comments and references
added. To appear in Nucl. Phys.
The geometry of supersymmetric coset models and superconformal algebras
An on-shell formulation of (p,q), 2\leq p \leq 4, 0\leq q\leq 4,
supersymmetric coset models with target space the group G and gauge group a
subgroup H of G is given. It is shown that there is a correspondence between
the number of supersymmetries of a coset model and the geometry of the coset
space G/H. The algebras of currents of supersymmetric coset models are
superconformal algebras. In particular, the algebras of currents of (2,2) and
(4,0) supersymmetric coset models are related to the N=2 Kazama-Suzuki and N=4
Van Proeyen superconformal algebras correspondingly.Comment: pages 2
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