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Speaker: Malte Buschmann (Princeton University)

Abstract: The axion is a hypothetical particle that solves thestrong CP problem of quantum chromodynamics (QCD) while simultaneously being anexcellent dark matter candidate. If the axion is generated after inflation,many unique objects arise from the theory, from axion strings and domain wallsto oscillons, miniclusters, and axion stars. The result is many potentiallyobservable signatures, whether in the CMB, the gravitational wave background orin neutron star data. More importantly, this scenario is entirely deterministic,allowing precise predictions through numerical simulations. In this talk, Iwill go through the cosmological history of such a post-inflationary axionto put the various phenomena into context and highlight the remaining openquestions.