New strategies to obtain insights into CP violation through Bs → Ds± K∓, Ds*± K∓, . . . and Bd → D±π∓, D*±π∓, . . . decays

Decays of the kind B-s --> Ds+/-K-/+, D-s*K-+/-(-/+), . . . and B-d --> D(+/-)pi(-/+), D*(+/-)pi(-/+), . . . allow us to probe phi(s) + gamma and phi(d) + gamma, respectively, involving the angle gamma of the unitarity triangle and the B-q(0)-(B) over bar (0)(q) mixing phases phi(q) (q is an element of {d, s}). Analysing these modes in a phase-convention-independent way, we find that their mixing-induced observables are affected by a subtle (-1)(L) factor, where L denotes the angular momentum of the B-q decay products, and derive bounds on phi(q) + gamma. Moreover, we emphasize that "untagged" rates are an important ingredient for efficient determinations of weak phases, not only in the presence of a sizeable width difference DeltaGamma(q); should DeltaGamma(s) be sizeable, the combination of "untagged" with "tagged" B-s --> Ds+/-K-/+, D-s*K-+/-(-/+), . . . observables provides an elegant and unambiguous extraction of tan(phi(s) + gamma), whereas the "conventional" determination of phi(s) + gamma is affected by an eightfold discrete ambiguity. Finally, we propose a combined analysis of B-s --> Ds+/-K-/+, D-s*K-+/-(-/+), . . . and B-d --> D(+/-)pi(-/+), D*(+/-)pi(-/+), . . . modes, which has important advantages, offering various interesting new strategies to extract gamma in an essentially unambiguous manner. (C) 2003 Elsevier B.V. All rights reserved.