Dartmouth Events

Abstract: Axions are attractive candidates for theories of large-field inflation that are capable of generating observable primordial gravitational wave backgrounds. These fields enjoy shift symmetries which protect the form of their action from large radiative-corrections. This symmetry also restricts the couplings of these axion fields to other matter fields. At lowest order, the only allowed interactions are derivative couplings to gauge fields and fermions. These derivative couplings lead to the biased production of fermion and gauge-boson helicity states during and after inflation. I will describe some recent work on  preheating in axion-inflation models that are derivatively coupled to Abelian gauge-fields and fermion axial-currents. The biased production of fermion helicity-states in these theories has interesting phenomenological implications for leptogenesis, while gauge preheating in this class of models can be extremely efficient, completing within a single oscillation of the axion.