Higgs relaxation after inflation

by Nayara Fonseca (DESY Hamburg)

Tuesday 15 May 2018, 14:00 → 15:00 Europe/Madrid

IFAE Seminar room (IFAE)

We show that the mechanism of cosmological relaxation of the electroweak scale can take place independently of the inflation mechanism, thus relieving burdens from the original relaxion proposal. What eventually stops the (fast-rolling) relaxion field during its cosmological evolution is the production of particles whose mass is controlled by the Higgs vacuum expectation value. We provide an analysis of the scanning and stopping mechanism and determine the parameter space for which the relaxion mechanism can take place after inflation, while being compatible with cosmological constraints, such as the relaxion overabundance and Big Bang Nucleosynthesis. We find that the cutoff scale can be as high as several hundreds of TeV. The stopping barriers of the periodic potential are large and Higgs-independent, facilitating model-building. As a result, the relaxion is quite heavy, from 0.1 GeV up to the cutoff. In this scenario, the relaxion field excursion is many orders of magnitude smaller than in the original relaxion proposal (subplanckian). We also discuss whether the relaxion may leave detectable signatures at future experiments.