First observation of the decay $B_s^0\to K_S^0{K}^{\ast }(892{)}^0$

Abstract

A search for $B_{(s)}^0\to K_S^0{K}^{\ast }(892{)}^0$ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of $1.0{\text{fb}}^{-1}$, collected with the LHCb detector at a centre-of-mass energy of $7\text{TeV}$. The $B_s^0\to K_S^0{K}^{\ast }(892{)}^0$ decay is observed for the first time, with a significance of 7.1 standard deviations. The branching fraction is measured to be \begin{equation*} \mathcal{B}(B_{s}^{0} \to \bar{K}^{0} K^{*}(892)^{0}) + \mathcal{B}(B_{s}^{0} \to K^{0} \bar{K}^{*}(892)^{0}) = (16.4 \pm 3.4 \pm 2.3) \times 10^{-6},\\ \end{equation*} where the first uncertainty is statistical and the second is systematic. No evidence is found for the decay $B^0\to K_S^0{K}^{\ast }(892{)}^0$ and an upper limit is set on the branching fraction, $\mathcal{B}(B^0\to {\bar{K}}^0{K}^{\ast }(892{)}^0)+\mathcal{B}(B^0\to K^0{\bar{K}}^{\ast }(892{)}^0)<0.96\times 10^{-6},$ at $90\%$ confidence level. All results are consistent with Standard Model predictions.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-018.html