Fibre inflation: observable gravity waves from IIB string compactifications

We introduce a simple string model of inflation, in which the inflaton field can take trans-Planckian values while driving a period of slow-roll inflation. This leads naturally to a realisation of large field inflation, inasmuch as the inflationary epoch is well described by the single-field scalar potential V = V0(3−4e−φ̂/(3)1/2). Remarkably, for a broad class of vacua all adjustable parameters enter only through the overall coefficient V0, …