Strong and Weak Phases from Time - Dependent Measurements of B → Ππ

Time-dependence in B(t) → ππ and B0(t) → ππ is utilized to obtain a maximal set of information on strong and weak phases. One can thereby check theoretical predictions of a small strong phase δ between penguin and tree amplitudes. A discrete ambiguity between δ ≃ 0 and δ ≃ π may be resolved by comparing the observed charge-averaged branching ratio predicted for the tree amplitude alone, using measurements of B → πlν and factorization, or by direct comparison of CabibboKobayashi-Maskawa (CKM) matrix parameters with those determined by other means. It is found that with 150 fb from BaBar and Belle, this ambiguity will be resolvable if no direct CP violation is found. In the presence of direct CP violation, the discrete ambiguity between δ and π − δ becomes less important, vanishing altogether as |δ| → π/2. The role of measurements involving the lifetime difference between neutral B eigenstates is mentioned briefly.