Bounding the penguin effects in determinations of alpha from B-0(t)->pi(+)pi(-) - art. no. 054020

In the absence of QCD penguin contributions a measurement of the time-depen dent asymmetry in the decay B-0(t)--> pi(+) pi(-) gives directly the weak a ngle alpha. Several bounds have been proposed in the literature on the magn itude of the penguin effects on this determination, the prototype of which is the isospin bound of Grossman and Quinn. We point out that large strong final state interactions could cause these bounds to overestimate the Teal penguin effect. A new flavor SU(3) bound is proposed, requiring only the ch arge-averaged branching ratios for B-0 --> pi(+)pi(-) and B-s-->K+K-, which exactly takes into account all relevant amplitudes and electroweak penguin effects. This bound on the penguin-induced error on the determination of t he weak phase cu holds even without knowledge of direct CP asymmetry in the pi(+)pi(-) channel. [S0556-2821(99)04715-3].