Observation of $B\to \varphi \varphi K$ Decays

Abstract

We report the observation of the decay $B^{\pm }\to \varphi \varphi K^{\pm }$ and find evidence for $B^0\to \varphi \varphi K^0$. These results are based on a 414 fb${}^{-1}$ data sample that contains $449\times 10^6$ $B\bar{B}$ pairs, collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ (3.5 on 8 GeV) collider operating at the ${\rm Y}(4S)$ resonance. This is the first observation of a $b\to s\bar{s}s\bar{s}s$ transition. The branching fractions for these decay modes are measured to be $\mathcal{B}(B^{\pm }\to \varphi \varphi K^{\pm })=(3.2_{-0.5}^{+0.6}\pm 0.3)\times 10^{-6}$ and $\mathcal{B}(B^0\to \varphi \varphi K^0)=(2.3_{-0.7}^{+1.0}\pm 0.2)\times 10^{-6}$ for $\varphi \varphi$ invariant mass below 2.85 GeV/$c^2$. The corresponding partial rate asymmetry for the charged $B$ mode is measured to be ${\mathcal{A}}_{CP}(B^{\pm }\to \varphi \varphi K^{\pm })=0.01_{-0.16}^{+0.19}\pm 0.02$. Results for other related charmonium decay modes are also reported. We also search for CP asymmetry using the $\varphi \varphi$ candidates within the ${\eta }_c$ mass region. The value obtained is ${\mathcal{A}}_{CP}(B^{\pm }\to \varphi \varphi K^{\pm },M_{\varphi \varphi }\approx M_{{\eta }_c})=0.15_{-0.17}^{+0.16}\pm 0.02$, which is consistent with no asymmetry.

10 pages, 3 figures, submitted to ICHEP06