Looking from the east at an elephant trotting west: direct CP violation in B0 decays

With the time dependent CP asymmetry in Bd(t)→ψKS well measured, the most powerful method to search for direct CP violation in Bd decays is to analyze whether the CP asymmetry of other transitions like Bd(t)→π+π−,η′KS, etc., can be described by a sin term taken from Bd(t)→ψKS and without a cos term. The failure of such a constrained fit would establish direct CP violation (even if no CP asymmetry were observed in these other modes).