Cosmological Relaxation from Dark Fermion Production

TL;DR

This paper proposes a cosmological relaxation mechanism for the electroweak hierarchy problem that involves dark fermion production, avoiding large field excursions and e-folds, and suggests these fermions could be warm dark matter candidates.

Contribution

It introduces a novel relaxation approach using dark fermion production via derivative coupling, eliminating the need for super-Planckian fields and extensive inflation.

Findings

Dark fermions can serve as keV-scale warm dark matter.

The relaxation mechanism avoids large field excursions and many e-folds.

Produced fermions are SM-singlets, acting as dark matter candidates.

Abstract

We consider the cosmological relaxation solution to the electroweak hierarchy problem using the fermion production as a dominant friction force. In our approach, neither super-Planckian field excursions nor a large number of e-folds arise, and scanning over thermal Higgs mass squared is avoided. The produced fermions from the relaxion source through the derivative coupling are SM-singlets, what we call dark fermions, and they can serve as the keV scale warm dark matter candidates.