Low-l CMB Power Loss and String Inflation
Dr. Alexander Westphal (DESY Hamburg)

abstract: "The PLANCK satellite may have observed a lack of power on large scales (l < 40). We argue that this putative feature can be explained by a phase of fast roll at the onset of inflation. We show that in the context of single field models what is required is an asymmetric inflection point model of which fibre inflation is a string motivated example. We study the ability of fibre inflation to generate a suppression of the CMB 2-point function power at low l, finding that the potential derived from string loops is almost but not quite steep enough for this purpose. We introduce a steeper contribution to the potential, that dominates away from the inflationary region, and show that if properly tuned it can indeed lead to a spectrum with lack of power at large scales."