Quantum Corrections to the Stochastic Gravitational Wave Background

Abstract: We study 1-loop corrections to the primordial stochastic background of gravitational waves produced during inflation. While in single-clock, at the leading order in slow-roll, quantum corrections keep the amplitude scale-free this is not the case when the pattern of symmetry breaking is different. In particular, when spatial diffeomorphisms are also broken during inflation as for solid inflation, a log-running in the external momentum is generated. We relate the appearance of a log-running to the spontaneous breaking of dilatation invariance. The running could be instrumental to distinguish single-clock from alternative models of inflation in future high sensitivity CMB polarisation and GWs experiments.