Speaker
Description
he CKM angle $\gamma$ ($\phi_3$) of the unitarity triangle is the only one that is accessible with tree-level decays in a theoretically clean way. The key method to measure $\gamma$ is through the interference between $B^+\to D^0 K^+$ and $B^+ \to \bar D^0 K^+$ decays that occurs if the final state of the charm-meson decay is accessible to both the $D^0$ and $\bar D^0$ mesons. The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. With the ultimate Belle II data sample of 50 ab$^-1$, a determination of $\gamma$ with a precision of 1 degree or better is foreseen. Main operation of SuperKEKB started in March 2019 and results from the full available Belle II data set, which corresponds to approximately 100~fb$^{-1}$, will be presented. The ratios of decay rates of $\Gamma(B^-\to D^{(*)0}K^-)/\Gamma(B^-\to D^{(*)0}\pi^-)$ and $\Gamma(\bar{B}^0\to D^{(*)+}K^-)/\Gamma(\bar{B}^0\to D^{(*)+}\pi^-)$ are measured. In addition, more detailed studies of $B^{-}\to D(K_{\rm S}^0\pi^{+}\pi^{-})K^-$, $B^{-}\to D(K_{\rm S}^0\pi^{0})K^-$ and $B^{-}\to D^{*0}(D^0\pi^0)K^-$ decays are described; these modes are key to the accurate determination of $\gamma$ at Belle II.
| First author | Jim Libby |
|---|---|
| libby@iitm.ac.in | |
| Collaboration / Activity | Belle II |
