Trapped axion misalignment mechanism

by Pablo Quilez Lasanta (DESY)

Friday 3 Sept 2021, 15:30 → 17:30 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

In this talk I will present a novel mechanism to produce axion dark matter in the early universe: trapped misalignment mechanism. As a consequence of a particular temperature dependence of the axion potential (with strong non-adiabaticities), two distinct stages of oscillations take place. The axion field is first trapped in the high temperature minimum and it is not until the true zero-temperature potential develops that the axion is free to oscillate around the final minimum. As a consequence the onset of true oscillations is delayed as compared with the standard QCD axion scenario, resulting in an enhancement of the DM relic density. Moreover if the axion kinetic energy at the end of trapping is larger than the potential barrier at low energies, the trapped misalignment then automatically seeds the recently proposed kinetic misalignment. In this case the axion rolls for a long time over the low-temperature potential barriers before final oscillations start, extending further the delay of oscillations around the true minimum.