The strong CP problem can be solved via the Peccei-Quinn mechanism. The resulting pseudo-Goldstone boson, the axion is a natural candidate for dark matter. In order to quantitatively understand axion dark matter production two important QCD inputs are required: the equation of state and the topological susceptibility at high temperatures. After reviewing the Peccei-Quinn mechanism and axion dark matter production in the early universe, recent lattice results on these quantities will be presented. They will be used to constrain the axion mass in different axion production scenarios.
Sándor Katz (ELTE Dept. Theor. Phys.)