Weak phases γ and α from B + , or B 0 and B s decays

An improved method is presented for determining the weak angle γ of the unitarity triangle using decay rates for B+ → Kπ,B+ → K+K̄0 and B+ → π+η (or B0 → Kπ and Bs → Kπ), their CP-conjugate modes and the CP-averaged rate for B → π±π0. Using SU(3) symmetry, the annihilation (color-suppressed) contribution in B+(B0) → Kπ decays is subtracted away. Electroweak penguin effects are included in a model-independent way. The only significant SU(3) breaking effects are accounted for in the factorization approximation of tree amplitudes. The weak angle α is obtained as a byproduct. Typeset using REVTEX