Connecting the Higgs Mass with Cosmic History

The mass of the recently discovered Higgs particle is one of the greatest mysteries in present-day particle physics. While much larger than the mass of most known elementary particles, it is far smaller than other energy scales. Within our current understanding of quantum mechanics and relativity, this disparity is puzzling and is referred to as the hierarchy or naturalness problem. One popular explanation is provided by a hypothesized new symmetry of nature, supersymmetry. Peter Graham from Stanford University, California, and collaborators [1] have now put forward an alternative theory in which the hierarchy among mass scales is a consequence of cosmic history. In their theory, the Higgs mass depends on the value of a field dubbed the relaxion. Like the gravitational field, the relaxion pervades all space. Immediately after the big bang, this field repeatedly changes, but at a certain point its value is frozen, and this value is predicted to give a mass to the Higgs comparable to that observed.