Successful modular cosmology

We present a modular cosmology scenario where the difficulties encountered inconventional modular cosmology are solved in a self-consistent manner, withdefinite predictions to be tested by observation. Notably, the difficulty ofthe dilaton finding its way to a precarious weak coupling minimum is madeirrelevant by having eternal modular inflation at the vacuum supersymmetrybreaking scale after the dilaton is stabilised. Neither this eternal inflationnor the subsequent non-slow-roll modular inflation destabilise the dilaton fromits precarious minimum due to the low energy scale of the inflation andconsequent small back reaction on the dilaton potential. The observed flat CMBspectrum is obtained from fluctuations in the angular component of a modulusnear a symmetric point, which are hugely magnified by the roll down of themodulus to Planckian values, allowing them to dominate the final curvatureperturbation. We also give precise calculations of the spectral index and itsrunning.Comment: 18 pages, 2 eps figures; appendices and footnotes adde