Higgs relaxation after inflation

Fonseca, Nayara; Servant, Geraldine; Morgante, Enrico

Preprint/Report

PUBDB-2018-02122

Higgs relaxation after inflation

Fonseca, N.DESY* ; Morgante, E. (Corresponding author)DESY* ; Servant, G.DESY*

2018

[10.3204/PUBDB-2018-02122]

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Please use a persistent id in citations: doi:10.3204/PUBDB-2018-02122

Report No.: DESY-18-069; arXiv:1805.04543

Abstract: 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 first show that Higgs particle production does not work for that purpose as the Higgs field does not track the minimum of its potential in the regime where Higgs particles get efficiently produced through their coupling to the relaxion. We then focus on gauge boson production. We provide a detailed 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. In this approach, the relaxion sector is responsible for reheating the visible sector. 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.

Keyword(s): Higgs particle: production ; gauge boson: production ; scale: electroweak interaction ; nucleosynthesis: big bang ; inflation ; reheating ; signature ; tracks