Speaker
Description
I will present an inclusive study of $B^+\!\to K^+ X_{c\bar c}$ and $B^+\!\to \bar D^{(*)0}\pi^+$ using $778~\mathrm{fb}^{-1}$ of Belle data and $362~\mathrm{fb}^{-1}$ of Belle~II data at $\sqrt{s}=10.58~\mathrm{GeV}$. The main goal is to measure the inclusive branching-fraction ratio $R_{X/J/\psi} = \mathcal{B}(B^+\!\to K^+ X(3872)) / \mathcal{B}(B^+\!\to K^+ J/\psi)$, where many systematics cancel, and to search for or constrain limit charmonium-like states such as $X(3915)$ and $X(3960)$ in the kaon recoil-mass spectrum. One $B$ meson is fully reconstructed in hadronic modes, while the signal $B$ is inferred from a single prompt kaon or pion and the known $e^+e^-$ initial state. Using the same framework, I also measure $R_{D^*/D} = \mathcal{B}(B^+\!\to\bar D^{*0}\pi^+)/\mathcal{B}(B^+\!\to\bar D^{0}\pi^+)$ and use the $B^+\!\to \bar D^{(*)0}\pi^+$ sample to provide data-driven constraints for the $B^+\!\to K^+ X_{c\bar c}$ fit.
