Axion Cosmology: from strings to dwarf galaxies

by David J E Marsh (Kings College London)

Monday 23 May 2016, 16:30 → 17:30 Europe/Berlin

seminar room 2, building 2A (DESY Hamburg)

The existence of axions and axion like particles is well motivated by field theory, supersymmetry, and string theory. They can play a variety of roles in cosmology: as inflatons, dark matter or dark energy. If they is particularly light, 10-33 eV<m<10-18 eV, axion dark matter can be constrained by the CMB and large scale structure. I will explain the origin of these constraints, which give the absolute lower bound on DM particle mass, m\gtrsim 10-22 eV. Light axions may also solve some problems with standard cold dark matter on small scales, and I will outline how. This low axion mass scale is challenging to direct detection, but several new experiments and analysis techniques are being investigated, with a bright future. I will describe one particular such experiment using ultracold neutrons.