Doubly CKM-suppressed corrections to CP asymmetries in B0→J/ψK0

A doubly CKM-suppressed amplitude in B0→J/ψKS leads to corrections in CP asymmetries S=sin2β, C=0, which may be enhanced by long-distance rescattering. It has been suggested that this enhancement may lead to several percent corrections. We calculate an upper bound of order 10−3 on rescattering corrections using measured branching ratios for charmless |ΔS|=1B0 decays.