Flux Backgrounds and Generalised Geometry
Typ
Examensarbete för masterexamen
Program
Physics and astronomy (MPPAS), MSc
Publicerad
2019
Författare
Eriksson, Magdalena
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
In this thesis we study aspects of compactifications of mainly the type II supergravity theories.
We begin with the study of classical approaches with a Kaluza-Klein compactification of the type
II supergravity theories on a Calabi-Yau 3-fold, followed by a presentation of their orientifold
variants, mirror symmetry, and the effects of allowing background fluxes on the moduli in the
4D effective field theory. The moduli fields can be stabilised by the presence of non-trivial
background fluxes, perturbative corrections to the 10D theory and non-perturbative corrections
to the 4D scalar potential. These corrections can be used to construct toy model de Sitter vacua
as in the KKLT and large volume scenarios. We also introduce a compactification with so-called
non-geometric fluxes, whose presence makes the metric of the internal manifold ill-defined. This
is followed by a discussion of double field theory, which treats geometric and non-geometric
fluxes on equal footing by extending spacetime in order to covariantise the T-duality group
O(d, d). We briefly discuss consistent truncations in the context of the generalised Scherk-
Schwarz ansatz. This is followed by an introduction of exceptional field theory, which is also an
extension of supergravity which covariantises the exceptional U-duality groups. This brings us
to the formalism of exceptional generalised geometry where we formulate supersymmetric flux
backgrounds as torsion-free generalised G-structures. The notion of generalised G-structures is
then interpreted as generalised differential forms in exceptional field theory and used to describe
vacua. The application to find consistent truncations to 4D is also discussed. This construction
is believed to play an important role in the classification of supersymmetric backgrounds.