Speaker
金葆 王
(河北师范大学)
Description
The decay $K\to\pi a$ provides the most stringent particle-physics constraints on ALPs with masses below 300 MeV. Previous studies have been performed within SU(3) chiral perturbation theory, where the $\eta_0$ is integrated out. However, the explicit $\eta_0$ may play an important role, since the ALP and the $\eta_0$ belong to the same flavor-singlet sector. In this talk, we discuss the $K\to\pi a$ decay in U(3) chiral perturbation theory, focusing on the explicit $\eta_0$ contribution, the new weak operator, and the large-$N_C$ behavior of the decay amplitude.
