The Fragility of Life and Post-Inflationary Axion Cosmology

by Prof. Frank Wilczek (Massachusetts Institute of Technology)

Tuesday 23 Oct 2007, 13:15 → 14:15 Europe/Stockholm

FA 32

The cosmological implications of axion physics are changed radically if inflation occurs after the phase transition where Peccei-Quinn symmetry is broken. The ratio of axion dark matter to baryons then varies over super-horizon scales (i.e., over "effective universes"). But regions in which the dark matter is very dominant are inhospitable to structure formation, and thus unobservable. When that selection effect is taken into account, a good prediction for the most likely dark matter density emerges. On the way to this conclusion, we must consider astrophysical issues of considerable independent interest.