HE Seminar
Speaker: Guido D'Amico (NYU)
Title: Unwinding Inflation
Host: Nemanja
Room: 416
Abstract: When electric-type flux winds around compact extra dimensions, a single quantum event can break a flux line and initiate a classical cascade that unwinds many units of flux. From the 4D point of view, this is the formation of a thin-wall bubble containing an open FRW cosmology, but---unlike Coleman-de Luccia bubble formation---the vacuum energy inside the bubble is initially only slightly reduced, and then decreases steadily throughout the cascade. If the initial number of flux quanta $Q \simgeq 100$, this can result in $N \simgeq 60$ efolds of inflationary expansion while producing a scale-invariant spectrum of adiabatic density perturbations, with amplitude and tilt consistent with observation. The power spectrum has a small oscillatory component that does not decay away during inflation, with a period set approximately by the light-crossing time of the compact dimension. Since the ingredients are fluxes wrapping compact dimensions, wound inflation fits naturally into the string landscape, but does not appear to suffer from the eta problem or require fine-tuning (beyond the usual anthropic requirement of small vacuum energy after reheating).
