Graviton one-loop effective action and inflationary dynamics

Understand

We consider the one-loop effective action due to gravitons in a FLRW background with constant epsilon=-(dH/dt)/H^2.

• By expanding around epsilon=0 (corresponding to an expansion around de Sitter space), we can study how the deviation from de Sitter space effects the quantum corrected Friedmann equations.
• We find that, at zeroth order in epsilon, one-loop effects induce only a finite shift in the coupling constants.
• At linear order in epsilon there is however a divergent contribution to the equations of motion.