Testing Higgs Relaxation Leptogenesis: Why Isocurvature Is More Promising Than CP Violation

In this talk, I will discuss how CP violation appears in Higgs relaxation leptogenesis, showing that it is subsumed into an effective "scale" of a dimension 6 operator, which is in fact a combination of the scale of new physics and the CP-violation in this new sector. Consequently, Higgs relaxation leptogenesis does not make concrete predictions for either the scale of new physics or the amount of CP violation independently of each other. I will then discuss, however, a different promising direction for testing Higgs relaxation leptogenesis: namely, it requires the production of cosmological isocurvature perturbations. Time permitting, I will end by discussing how this can affect the production of earliest stars.