Lessons from LHCb and Belle II measurements of B → J/ψπ and B → J/ψK decays

A bstract The LHCb collaboration has recently measured the CP asymmetry in B + → J/ψπ + decay, while the Belle II collaboration has recently measured the CP asymmetries in B 0 → J/ψπ 0 decay. Within the Standard Model, and using flavor-SU (3) relations including first-order breaking corrections, these measurements lead to new predictions with regard to CP violation in B + → J/ψK + and Bₒ J/ K ^0 decays, the difference between S ₊ₒ and sin 2 β, and the rate and CP asymmetries in B s → J/ψπ 0 decay.