Measurement of φs and Δγs at the Tevatron

We present bounds on the CP violation phase φs and on the decay width difference ΔΓs which characterize the neutral Bs0-(bar B)s0 meson system. The measurements are performed by the CDF and D0 experiments at the Fermilab Tevatron using Bs0 → J/Ψφ decays with 2.8 fb-1 of data per experiment. A data sample of 5 fb-1 has already been recorded by each experiment and expect up to doubling this amount by the end of the Tevatron running. Neither of the two Tevatron experiments can provide accurate measurement of the CP violation phase with the current or even expected sample sizes. However they can significantly constrain the allowed parameter space and search for physics beyond the standard model manifested as a large deviation from zero of the CP violation parameter φs.