Search for $B^{+}\to J/\psi {\eta }^{\prime }{K}^{+}$ and $B^0\to J/\psi {\eta }^{\prime }{K}_S^0$ decays

We report the results of searches for $B^{+}\to J/\psi {\eta }^{\prime }{K}^{+}$ and $B^0\to J/\psi {\eta }^{\prime }{K}_S^0$ decays, using a sample of $388\times {10}^6$ $B\overline{B}$ pairs collected with the Belle detector at the ${\rm Y}(4S)$ resonance. No statistically significant signal is found for either of the two decay modes and upper limits for the branching fractions are determined to be $\mathcal{B}(B^{+}\to J/\psi {\eta }^{\prime }{K}^{+})<8.8\times {10}^{-5}$ and $\mathcal{B}(B^0\to J/\psi {\eta }^{\prime }{K}_S^0)<2.5\times {10}^{-5}$ at 90% confidence level.

Figure 1

(a) The $(M_{\mathrm{bc}},\Delta E)$ scatterplot of $B^{+}\to J/\psi {\eta }^{\prime }{K}^{+}$ candidates and its projections onto (b) $\Delta E$ with $5.27\mathrm{GeV}/c^2<M_{\mathrm{bc}}<5.29\mathrm{GeV}/c^2$ and (c) $M_{\mathrm{bc}}$ with $|\Delta E|<0.03\mathrm{GeV}$. The dashed lines and solid boxes indicate the signal regions. The curves are the result of the fit as described in the text.

Figure 2

(a) The $(M_{\mathrm{bc}},\Delta E)$ scatterplot of $B^0\to J/\psi {\eta }^{\prime }{K}_S^0$ candidates and its projections onto (b) $\Delta E$ with $5.27\mathrm{GeV}/c^2<M_{\mathrm{bc}}<5.29\mathrm{GeV}/c^2$ and (c) $M_{\mathrm{bc}}$ with $|\Delta E|<0.03\mathrm{GeV}$. The dashed lines and the solid box indicate the signal regions. The curves are the result of the fit.