Guest speaker: Kenichi Saikawa
Abstract:
Axions are well-motivated hypothetical particles as they arise as a solution to the strong CP problem of QCD and are regarded as a good candidate for cold dark matter. The theoretical prediction for the axion dark matter mass is however still an open problem and a fast-developing topic in astroparticle physics. The prediction for the axion dark matter mass can be obtained by fixing its relic abundance, which is not straightforward to estimate since we must take account of the contribution of axions radiated from global strings if the Pecceci-Quinn symmetry is restored and broken after inflation. In this talk, we review the issue of the production mechanism of dark matter axions and present the results of recent large scale numerical simulations on the axionic strings.
