Inflation on Moduli Space and Cosmic Perturbations

By Kenji Kadota, Fermilab

Early Universe cosmology along with unprecedented wealth of observational data offers one of few opportunities to test the framework of particle theory phenomenology at high energy scales well beyond those of collider physics, in particular string/M-theory phenomenology. Indeed, the existence of ubiquitous moduli is a generic feature of string/M-theory and much attention has been drawn to `modular cosmology.' Unfortunately, despite many attempts to find viable cosmology scenarios associated with moduli, they turned out to give us cosmological obstacles rather than attractive features. We shall discuss that a careful analysis of rich structure of moduli space, in particular the generic existence of multiple points of enhanced symmetry which is not usually considered in inflation model building, naturally leads to self-consistent modular cosmology scenario without fine-tuning for the form of modular potential expected from simple hidden sector symmetry breaking without any modifications. Our scenario also predicts characteristic behaviors of cosmic perturbations with possible running of spectrum at small scales, which can be tested in the forthcoming experiments such as Planck.