Phenomenological Determination of the Beauty Meson Decay Parameter $f_B$ and the CP-Violating Angle $\delta$

Abstract

We fit the ${\cal CKM}$-matrix to all recent data with the following free parameters: three mixing angles, the CP-violating angle $\delta$ in the Maiani parametrisation, the top quark mass $m_t$, and the product $f_B{\cal B}_{\B}^{1/2}$, where $f_B$ is the $B$-meson decay parameter and ${\cal B}_{\B}$ is the bag parameter. Our fits span a contiguous region in the $(f_B{\cal B}_{\B}^{1/2},\ \cos\delta)$--plane, limited by $0.117\lsim f_B{\cal B}_{\B}^{1/2}/{\rm GeV}\lsim 0.231$ and --0.95 $\lsim$ $\cos\delta$ $\lsim$ 0.70. The parameters $f_B{\cal B}_{\B}^{1/2}$ and $\cos\delta$ are strongly positively correlated.