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

Abstract

Decays of neutral B mesons originating from b→ Dr ( r∈{ s, d}) processes, i.e., B d → DK S(L), B s → Dη (′), Dφ,… ( r= s) and B s → DK S(L), B d → Dπ 0, Dρ 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, s → D ± f s observables provide a very efficient, theoretically clean determination of the angle γ of the unitarity triangle. Here we perform a more detailed analysis of the B d, s → D[→ f ±] f s channels, and focus on B d, 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 γ can nevertheless be determined in an elegant and essentially unambiguous manner from the B d, s → D[→ f NE] f s observables with the help of the corresponding “untagged” B d, 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, s → Df d are also pointed out.