Gravitational tests of electroweak relaxation

Understand

We consider a scenario in which the electroweak scale is stabilized via the relaxion mechanism during inflation, focussing on the case in which the back-reaction potential is generated by the confinement of new strongly interacting vector-like fermions.

• If the reheating temperature is sufficiently high to cause the deconfinement of the new strong interactions, the back-reaction barrier then disappears and the Universe undergoes a second relaxation phase.
• This phase stops when the temperature drops sufficiently for the back-reaction to form again.
• We identify the regions of parameter space in which the second relaxation phase does not spoil the successful stabilization of the electroweak scale.