Constraints on relaxion windows
Abstract
We examine the low energy phenomenology of the relaxion solution to the weak scale hierarchy problem. Assuming that the Hubble friction is responsible for a dissipation of the relaxion energy, we identify the cosmological relaxion window which corresponds to the parameter region compatible with a given value of the acceptable number of inflationary e-foldings. We then discuss a variety of observational constraints on the relaxion window, including those from astrophysical and cosmological considerations. We find that majority of the parameter space with a relaxion mass m ϕ ≳ 100 eV or a relaxion decay constant f ≲107GeV is excluded by existing constraints. There is an interesting parameter region with m ϕ ∼ 0 .2 - 10 GeV and f ∼ few - 200 TeV, which is allowed by existing constraints, but can be probed soon by future beam dump experiments such as the SHiP experiment, or by improved EDM experiments.
- Publication:
-
Journal of High Energy Physics
- Pub Date:
- December 2016
- DOI:
- 10.1007/JHEP12(2016)093
- arXiv:
- arXiv:1610.00680
- Bibcode:
- 2016JHEP...12..093C
- Keywords:
-
- Beyond Standard Model;
- Cosmology of Theories beyond the SM;
- Higgs Physics;
- High Energy Physics - Phenomenology;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 27 pages, 4 figures