Szczegóły publikacji

Searches are presented for $B_c^+ \to D h^+ h^-$ decays, where $D$ is a charmed meson and $h^\pm$ denotes a charged pion or kaon, using $pp$ collision data collected by the LHCb experiment corresponding to an integrated luminosity of $9\,\mathrm{fb}^{-1}$. The decays $B_c^+ \to D^+ K^+ \pi^-$, $B_c^+ \to D^{*+} K^+ \pi^-$, and $B_c^+ \to D_s^+ K^+ K^-$ are observed for the first time. Their branching fractions, expressed as ratios relative to that of the $B_c^+ \to B_s^0 \pi^+$ decay, are determined to be \begin{align} \mathcal{R}(B_c^+ \to D^+ K^+ \pi^-) &= (1.96 \pm 0.23 \pm 0.08 \pm 0.10)\times 10^{-3}, \\ \mathcal{R}(B_c^+ \to D^{*+} K^+ \pi^-) &= (3.67 \pm 0.55 \pm 0.24 \pm 0.20)\times 10^{-3}, \\ \mathcal{R}(B_c^+ \to D_s^+ K^+ K^-) &= (1.61 \pm 0.35 \pm 0.13 \pm 0.07)\times 10^{-3}, \end{align} where the first uncertainty is statistical, the second is systematic, and the third arises from the limited precision on the $D$-meson branching fractions. The decay channels proceed primarily via excited $K^0$ or $D^0$ resonances or $\phi$ mesons, and open a new avenue for studies of charge--parity violation in beauty mesons.