Orateur
Ryosuke Sato
(Osaka University)
Description
The QCD axion is the most interesting solution for the strong CP problem. The QCD axion is the Nambu-Goldstone boson which is associated with spontaneous breaking of Peccei-Quinn symmetry and can absorb theta-term at its potential minimum. However, an explicit breaking of Peccei-Quinn symmetry easily jeopardizes the QCD axion as a solution to the strong CP problem. Thus, the quality of Peccei-Quinn symmetry must be extremely high and this is so-called the axion quality problem. In this talk, we review the axion quality problem and discuss possible solutions.
