Measuring $-2\beta_s$ with $B_s0 \to J/psi f_0(980)$ Decays at LHCb*

We present the capability of measuring the CP violating phase in $B_s0$ mixing ($-2\beta_s$) using $B_s0 \to J/psi f_0(980)$ and $B_s0 \to J/psi phi$ decays at LHCb. Both CDF and D0 have investigated $-2\beta_s$ using $B_s \to J/psi \phi$ decays. The central value has been found far from the Standard Model predictions, but the error is large and significance of the possible discrepancy is in the 2-3 $\sigma$ range.