Observation of the decay $B_s^0\to J/\psi \eta$ and Evidence for $B_s^0\to J/\psi {\eta }^{\prime }$

Abstract

We report the first observation of $B_s^0\to J/\psi \eta$ and evidence for $B_s^0\to J/\psi {\eta }^{\prime }$. These results are obtained from $23.6{\mathrm{fb}}^{-1}$ of data collected at the ${\rm Y}(5S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We measure the branching fractions $\mathcal{B}(B_s^0\to J/ψη)= (3.32 \pm 0.87(\mathrm{stat.})^{+0.32}_{-0.28}(\mathrm{syst.}) \pm 0.42(f_s))\times 10^{-4}}$ with a significance of $7.3\sigma$, and $\mathcal{B}(B_s^0\to J/\psi {\eta }^{\prime })=(3.1\pm 1.2(stat.{)}_{-0.6}^{+0.5}(syst.)\pm 0.38(f_s))\times 10^{-4}$ with a significance of $3.8\sigma$.

arXiv comment6 pages, 3 figures, 2 tables. Contributed to Moriond QCD 09, FPCP 09, EPS HEP 09, DPF 09, and BEAUTY 09