New rare meson decay constraints on a light vector in $U(1{)}_{B-L},U(1{)}_R$ and the dark photon

Osamu Seto, Takashi Shimomura, Shinsuke Yoshida

We evaluate constraints from flavor changing rare meson decays to a light vector boson $X$, followed by the decay of the on-shell $X$ into the SM fermions. The flavor changing meso…