Dante’s Waterfall: A Hybrid Model of Inflation

Given recent observational results from the BICEP2 and Planck collaborations regarding the ratio of power in tensor to scalar modes in the cosmic microwave background radiation, and the implications of this ratio for the possible existence of large gravity waves resulting from inflation, it is of current interest to investigate models of inflation which are capable of producing large gravity waves. We examine a hybrid axion monodromy model we call “Dante’s Waterfall”. In this model, the inflaton rolls slowly along a trench in the potential, and inflation ends when this trench becomes unstable and the inflaton rapidly approaches the global minimum of the potential. We find that this model is incapable of producing large gravity waves. We then introduce a vector interpretation of inflaton motion along a potential, and show that this can be useful in considering non-trivial kinetic terms which could give rise to large gravity waves in a hybrid model.