Relaxion

A hypothetical, ultra-light scalar particle that is itself a candidate for the Higgs boson. Proposed as a novel solution to the Hierarchy Problem, the relaxion mechanism suggests that the Higgs mass is not fixed but dynamic. In the early universe, it could "roll" or relax down its potential, scanning through many possible values. Its rolling stops (or "gets stuck") due to its interactions with the QCD vacuum or a new confining sector, naturally landing the Higgs mass at the small, observed value without extreme fine-tuning. This elegantly explains the weakness of the electroweak scale compared to the Planck scale. The relaxion itself, if it exists, would be a very light, very weakly interacting particle, potentially a component of dark matter or detectable in precision experiments.