CHARMING PENGUINS IN B-DECAY

Full expressions of the B-d(0) --> pi(+)pi(-) and B-d(0) --> pi(0) pi( 0) amplitudes, given in terms of matrix elements of operators of the e ffective weak Hamiltonian, are used to study the dependence of the rel evant branching ratios on the different contributions, The uncertainty in the extraction of the weak phase alpha from the measurement of the time-dependent asymmetry in B-d(0) --> pi(+)pi(-) decays is also anal yzed. We find that, among several effects which may enhance the B-d(0) pi(0) pi(0) branching ratio, the most important is due to ''charming penguin'' diagrams. These diagrams easily increase BR(B-d(0) --> pi(0) pi(0)) up to a value of 1-3 x 10(-6). The same effect produces, howev er, a large error in the extraction of alpha from the measurement of t he B-d(0) --> pi(+)pi(-) time-dependent asymmetry. We show that it is possible to determine charming-penguin amplitudes from the experimenta l measurement of many decay rates. Their effect is impressive in B+ -- > pi(+)K(0) and B-d(0) --> K(+)pi(-) decays, where charming-penguin co ntributions easily give values of BR(B+ --> pi(+)K(0)) and BR(B-d(0) - -> K(+)pi(-)) of about 1 x 10(-5), Among other possibilities, we also suggest to use B-d(0) --> K-0 (K) over bar(0), the BR of which can be as large as 2-3 x 10(-6), to determine the size of charming-penguin am plitudes. (C) 1997 Published by Elsevier Science B.V.