11 research outputs found
Non-relativistic Matrix Inflation
We reconsider a string theoretic inflationary model, where inflation is
driven by multiple coincident -branes in the finite limit. We show
that the finite action can be continued to the limit of large , where it
converges to the action for a wrapped -brane with units of U(1) flux.
This provides an important consistency check of the scenario and allows for
more control over certain back-reaction effects. We determine the most general
form of the action for a specific sub-class of models and examine the
non-relativistic limits of the theory where the branes move at speeds much less
than the speed of light. The non-Abelian nature of the world-volume theory
implies that the inflaton field is matrix valued and this results in
modifications to the slow-roll parameters and Hubble-flow equations. A specific
small field model of inflation is investigated where the branes move out of an
AdS throat, and observational constraints are employed to place bounds on the
background fluxes.Comment: 25 page
Fluxbranes: Moduli Stabilisation and Inflation
Fluxbrane inflation is a stringy version of D-term inflation in which two
fluxed D7-branes move towards each other until their (relative) gauge flux
annihilates. Compared to brane-antibrane inflation, the leading-order
inflationary potential of this scenario is much flatter. In the present paper
we first discuss a new explicit moduli stabilisation procedure combining the F-
and D-term scalar potentials: It is based on fluxed D7-branes in a geometry
with three large four-cycles of hierarchically different volumes. Subsequently,
we combine this moduli stabilisation with the fluxbrane inflation idea,
demonstrating in particular that CMB data (including cosmic string constraints)
can be explained within our setup of hierarchical large volume CY
compactifications. We also indicate how the eta-problem is expected to
re-emerge through higher-order corrections and how it might be overcome by
further refinements of our model. Finally, we explain why recently raised
concerns about constant FI terms do not affect the consistent, string-derived
variant of D-term inflation discussed in this paper.Comment: In section 3 an improved model is discusse