A closer look at Bd,s → Dfr decays and novel avenues to determine γ

Decays of neutral B mesons originating from b --> Dr (r epsilon {s, d}) processes, i.e., B-d --> DKS(L), B-s --> Deta(()'()), Dphi,... (r = s) and B-s --> DKS(L), B-d --> Dpi(0), D-rho(0),... (r = d) modes, offer valuable insights into CP violation. Here the neutral D mesons may be observed through D --> f+/- or D --> f(NE), where f+/- and f(NE) are CP eigenstates and CP non-eigenstates, respectively. Recently, we pointed out that "untagged" and mixing-induced CP-violating B-d,B-s --> D+/-f(s) observables provide a very efficient, theoretically clean determination of the angle gamma of the unitarity triangle. Here we perform a more detailed analysis of the B-d,B-s --> D[--> f+/-]f(s) channels, and focus on B-d,B-s --> D[-->f(NE)]f(s), where interference effects between Cabibbo-favoured and doubly Cabibbo-suppressed D-meson decays lead to complications. We show that gamma can nevertheless be determined in an elegant and essentially unambiguous manner from the B-d,B-s --> D[--> f(NE)]f(s) observables with the help of the corresponding "untagged" B-d,B-s --> D[--> f+/-]f(s) measurements. Moreover, we may also extract hadronic B- and D-decay parameters. Several interesting features of decays of the kind B-d,B-s --> Df(d) are also pointed out. (C) 2003 Elsevier Science B.V. All rights reserved.