Measurement of Branching Fraction and Search for $CP$ Violation in $Bto phi phi K$

We report the measurement of branching fractions and $CP$-violation asymmetries in $Bto phi phi K$ decays based on a $711,{rm fb}^{-1}$ data sample containing $772times 10^6$ $Bbar{B}$ events. The data were recorded at the $Upsilon (4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. For $B^+ to phi phi K^+$, the branching fraction and $CP$-violation asymmetry measured below the $eta_{c}$ threshold ($m_{phiphi}<2.85,{rm GeV}/c^2$) are $[3.43^{,+,0.48}_{,-,0.46}({rm stat})pm 0.22({rm syst})] times10^{-6}$ and $-0.02pm0.11({rm stat})pm0.01({rm syst})$, respectively. Similarly, the branching fraction obtained for $B^0 tophiphi K^0$ below the $eta_{c}$ threshold is $[3.02^{,+,0.75}_{,-,0.66} ({rm stat})pm ,0.20({rm syst})]times10^{-6}$. We also measure the $CP$-violation asymmetry for $B^+ tophiphi K^+$ within the $eta_{c}$ region ($m_{phiphi}in [2.94,3.02],{rm GeV}/c^2$) to be $+0.12pm0.12({rm stat})pm0.01({rm syst})$.