Measurement of Branching Fractions for $B\to {\eta }_c{K}^{(*)}$ Decays

We report measurements of branching fractions for charged and neutral $B\to {\eta }_{c}K$ decays where the ${\eta }_c$ meson is reconstructed in the $K_S^0{K}^{\pm }{\pi }^{\mp }$, $K^{+}{K}^{-}{\pi }^0$, $K^{*0}{K}^{-}{\pi }^{+}$, and $p\overline{p}$ decay channels. The neutral $B^0$ channel is a $CP$ eigenstate and can be used to measure the $CP$ violation parameter $\sin 2{\phi }_1$. We also report the first observation of the $B^0\to {\eta }_c{K}^{*0}$ mode. The results are based on an analysis of $29.1{\mathrm{f}\mathrm{b}}^{-1}$ of data collected by the Belle detector at KEKB.

Figure 1

(a) $M_{\mathrm{b}\mathrm{c}}$ and (b) $\Delta E$ distributions for $B\to {\eta }_{c}K$ candidates in all the decay modes.

Figure 2

Candidate $M({\eta }_c)$ invariant mass distribution for events in the $M_{\mathrm{b}\mathrm{c}}$ and $\Delta E$ signal region. Signals at the ${\eta }_c$ and $J/\psi$ masses from $B\to {\eta }_{c}K$ and $B\to J/\psi K$ decays are visible.

Figure 3

(a) $M_{\mathrm{b}\mathrm{c}}$ and (b) $\Delta E$ distributions for $B\to {\eta }_c{K}^{*0}$ candidates.