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

Decays of neutral B mesons originating from b→Dr (r∈{s,d}) processes, i.e., Bd→DKS(L), Bs→Dη(′),Dφ,… (r=s) and Bs→DKS(L), Bd→Dπ0, Dρ0,… (r=d) modes, offer valuable insights into CP violation. Here the neutral D mesons may be observed through D→f± or D→fNE, where f± and fNE are CP eigenstates and CP non-eigenstates, respectively. Recently, we pointed out that “untagged” and mixing-induced CP-violating Bd,s→D±fs 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 Bd,s→D[→f±]fs channels, and focus on Bd,s→D[→fNE]fs, 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 Bd,s→D[→fNE]fs observables with the help of the corresponding “untagged” Bd,s→D[→f±]fs measurements. Moreover, we may also extract hadronic B- and D-decay parameters. Several interesting features of decays of the kind Bd,s→Dfd are also pointed out.