H. Liu

A prominent $π^{0}π^{0}$ mass threshold enhancement, mirroring the $π^+π^-$ channel, is definitively observed in $ψ(3686)$ decays, challenging simple chiral descriptions.

$U$-spin symmetry is substantially broken in $D^0 \to K\pi\pi$ decays, with measured breaking parameters reaching magnitudes up to $4.45$.