Leptogenesis in Cosmological Relaxation with Particle Production
  Cosmological relaxation of the electroweak scale is improved by using
particle production to trap the relaxion. We combine leptogenesis with such a
relaxion model that has no extremely small parameters or large e-foldings.
Scanning happens after inflation--now allowed to be at a high scale--over a
sub-Planckian relaxion field range for an $\mathcal{O}(100)$ TeV cut-off scale
of new physics. Particle production by the relaxion also reheats the universe
and generates the baryonic matter-antimatter asymmetry. We propose a
realisation in which out-of-equilibrium leptons, produced by the relaxion,
scatter with the thermal bath through interactions that violate CP and lepton
number via higher-dimensional operators. Such a minimal effective field theory
setup, with no new physics below the cut-off, naturally decouples new physics
while linking leptogenesis to relaxion particle production; the baryon
asymmetry of the universe can thus be intrinsically tied to a weak scale
hierarchy.
