Determining the Ckm Unitarity Triangle from B Decays to Charged Pions and Kaons

Decay rates of B(t) → ππ, B → πK, B → πK (KS → π π) and of charge-conjugate processes are studied within flavor SU(3) symmetry and first-order SU(3) breaking. We show that these measurements can determine with a reasonable accuracy the two angles, α and γ, of the CabibboKobayashi-Maskawa unitarity triangle. B decays provide a variety of CP asymmetry measurements [1], which can test the currently favored hypothesis that phases in elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix [2] are the source of the observed CP violation in the neutral kaon system [3]. The time-dependent rate-asymmetry between the process B(t) → ππ and its CP-conjugate measures one of these phases, the angle α of the CKM unitarity triangle. Penguin amplitudes [4] and higher order electroweak penguin contributions [5] complicate the situation somewhat. However, by measuring also the rates of B → ππ, B → ππ and of their charge-conjugate counterparts one can isolate the amplitudes contributing to final states with isospin 0 and 2 and thereby determine α with a rather good accuracy [6, 7]. The detection of the modes involving neutral pions poses an interesting challenge for future experiments. To be submitted to Physical Review Letters. Permanent address.