Informal Pizza Seminar

The Endpoint of Brane-Antibrane Inflation

Neil Barnaby

McGill

I will review recent progress in constructing a string theory realization of hybrid inflation in which the inter-brane separation plays the role of the inflaton and the open string tachyon plays the role of the `waterfall' field which provides a graceful exit from inflation. I will focus on the end of inflation, after the tachyonic instability has set in, describing how reheating could work in such a model. I will also review the effective description of the open string tachyon and show how its peculiar dynamics modifies the usual picture of defect formation at the end of inflation and leads to a higher density of defects than previous studies have suggested. I will then discuss the defect network evolution and the cosmological significance of this overproduction of defects, showing that some models may already be ruled out due to overclosure.