This paper summarises the recent results of the Run IIa D0 experiment at the Tevatron Collider at Fermilab on the observable parameters of the $B_{ s}$ meson. A measurement of the branching fraction $B_s->D_s^{ (*)}D_s^{ (*)}$ is reported, which provides an estimate of the width difference $\Delta\Gamma_{ s}^{ CP}/\Delta\Gamma_{ s}$. Through the decay $B_{ s} \to J/\psi \phi$ the width difference $\Delta\Gamma_{ s}$ is extracted, and for the first time a constraint is set on the CP-violating phase $\phi_{ s}$, although a four-fold ambiguity remains. This result is combined with other D0 measurements to yield $\Delta\Gamma_{ s}=0.13\pm0.09 { \rm ps^{ -1}}$, $\phi_{ s} = -0.70^{ +0.47}_{ -0.39}$.
Categories: hep-ex