# Fixing D7 brane Positions by F-Theory Fluxes

Roberto Valandro (Uni Heidelberg)

04.12.2008 at 16:15

To do realistic model building in type IIB supergravity, it is important
to understand how to fix D7-brane positions by choice of fluxes. More
generally, F-theory model building requires the understanding of how
fluxes determine the singularity structure (and hence gauge group and
matter content) of the compactification. We analyse this problem in the
simple setting of M-theory on K3xK3, where we are able to show explicitly
how fluxes stabilise D7-branes or stacks of D7-branes. The analysis is
based on a parametrisation of the moduli space of type IIB string theory
on T2/Z2 (including D7-brane motion) in terms of the periods of integral
cycles of M-theory on K3. This allows us, in particular, to select a
specific desired gauge group by the choice of flux numbers.

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