Measurement of the branching fraction $BR(B^\pm\to \phi K^\pm)/BR(B^\pm \to J/\psi K^\pm)$ and the direct $C\!P$ asymmetry in $BR(B^\pm\to \phi K^\pm)$




Text for the blessed web page - CDF note 6966

The CDF Collaboration

Date: 14 February 2005

Abstract:

We present a measurement of $B\!R(B^{\pm} \rightarrow \phi K^{\pm})/B\!R(B^{\pm} \rightarrow J/\psi K^{\pm})$ using the complete sample Two Track Trigger data produced with offline version 4.8.4, corresponding to $180 \pm 10$ pb$^{-1}$. From an unbinned multidimensional maximum-likelihood fit to several discriminating variables we extract the yield and the charge asymmetry of the selected events. We obtain

$$\frac{BR(B^{\pm} \rightarrow \phi K^{\pm})}{BR(B^{\pm} \rightarrow J/\psi K^{\pm})}= 0.0076\pm 0.0013\:(stat.) \pm 0.0006\:(syst.) ,$$

and

$$A_{C\!P}(B^{\pm} \rightarrow \phi K^{\pm}) = -0.07 \pm 0.17\:(stat.) ^{+0.03}_{-0.02}\:(syst.) .$$