Linear Inflation from Axion Monodromy

          @misc{ pirsa_PIRSA:09010019,
            doi = {10.48660/09010019},
            url = {https://pirsa.org/09010019},
            author = {McAllister, Liam},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {Linear Inflation from Axion Monodromy},
            publisher = {Perimeter Institute},
            year = {2009},
            month = {jan},
            note = {PIRSA:09010019 see, \url{https://pirsa.org}}
          }
          

Abstract

Inflationary scenarios with detectable primordial tensor perturbations typically require symmetries that can protect the potential over a super-Planckian field excursion. An old and natural idea is for the inflaton to be an axion protected by a shift symmetry. However, this has appeared difficult to realize in string theory because axion periodicities are sub-Planckian in known examples. I will explain how in compactifications containing wrapped fivebranes, the effective axion range is increased by monodromy: a single axion period can be traversed many times. The resulting potential is approximately linear and can source technically natural large-field inflation. As a result of the all-orders axionic shift symmetry, the potential receives negligible corrections from moduli stabilization.