Abstract
We consider an ultra-light scalar coupled to the Higgs in the presence of heavier new physics. In the electroweak broken phase the Higgs gives a tree-level contribution to the light-scalar potential, while new physics contributes at loop level. Thereby, the theory has a cosmologically meta-stable phase where the light scalar is around the top of its potential, and the Higgs is a loop factor lighter than new physics. Such regions with precarious naturalness are anthropically and environmentally selected, as regions with heavier Higgs crunch quickly. We expect observable effects of rolling in the dark-energy equation of state. Furthermore, vacuum energies up to the weak scale can be canceled down to anthropically small values.
Highlights
Scalars with mass m below the present Hubble scale H0 can still lie away from the minimum of their potential and thereby undergo significant cosmological evolution at present times
In the electroweak broken phase the Higgs gives a tree-level contribution to the light-scalar potential, while new physics contributes at loop level
The squared Higgs mass might receive unnaturally large corrections from heavy new physics, but what matters here is its value renormalized around the weak scale
Summary
Scalars with mass m below the present Hubble scale H0 can still lie away from the minimum of their potential and thereby undergo significant cosmological evolution at present times. Values of φ such that the Higgs mass is a loop factor lighter than new physics This observation is relevant for the Higgs-mass hierarchy problem if, for some reason, φ lies close to the maximum of its potential. In this way, only regions where the Higgs is light are long-lived: a small Higgs mass is selected. We find that this setting allows for a range of values of the vacuum energy, up to the weak scale in the most optimistic case, thereby providing a mechanism (alternative to a landscape of vacua) for the anthropic selection of the cosmological constant down to the small observed value This scenario generates a little hierarchy, making the weak scale one or two loop factors below the scale of new physics.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
