Weak phase γ from the ratio of B→Kπ rates

The ratio of partial decay rates for charged and neutral B mesons to K pi final states provides information on the weak phase gamma=Arg(V-ub*) when augmented with information on the CP-violating asymmetry in the K(+/-)pi(-/+) mode. The requirements for a useful determination of gamma are examined in the light of present information about the decays B-o-->K(+)pi(-), B+-->K-0 pi(+), and the corresponding charge-conjugate modes. The effects of electroweak penguin diagrams and rescattering corrections are noted, and proposals are made for estimating and measuring their importance.