Quantum corrections to inflation: the importance of RG-running and choosing the optimal RG-scale

Understand

We demonstrate the importance of correctly implementing RG-running and choosing the RG-scale when calculating quantum corrections to inflaton dynamics.

• We show that such corrections are negligible for single-field inflation, in the sense of not altering the viable region in the $n_s-r$ plane, when imposing Planck constraints on $A_s$.
• Surprisingly, this also applies, in a nontrivial way, for an inflaton coupled to additional spectator degrees of freedom.
• The result relies on choosing the renormalisation scale (pseudo-)optimally, thereby avoiding unphysical large logarithmic corrections to the Friedmann equations and large running of the couplings.