Geneva University seminars

# The axion vs the WIMP

## by Sacha Davidson (Universite Claude Bernard-Lyon I (FR))

Friday, 6 December 2013 from to (Europe/Zurich)
at Geneva University ( Room 234 )
24 quai E. Ansermet, CH-1211 Genève 4
 Description The QCD axion is a micro->milli eV boson arising in extensions of the Standard Model which solve the "strong CP problem". It is consistent with astrophysical observations of the cooling timescale of stars. Non-thermal production mechanisms in the early Universe allow the axions, despite their neutrino-scale mass, to behave like Cold Dark Matter: their energy density redshifts like matter, and their density fluctuations grow like CDM. I aim to review the above, and explore the question of how to distinguish axions from WIMPs, in particular during non-linear stucture formation. Sadly, I have not an answer.