Measurement of the CP Violating Phase φs in anti-B0s → J/ψ f0(980)

Measurement of mixing-induced CP violation in anti-B0s decays is of prime importance in probing new physics. So far only the channel anti-B0s → J/ψ φ has been used. Here we report on a measurement using an LHCb data sample of 0.41 fb^−1, in the CP odd eigenstate J/ψ f0(980), where f0(980) → π+ π−. A time-dependent fit of the data with the anti-B0s lifetime and the difference in widths of the heavy and light eigenstates constrained to the values obtained from anti-B0s → J/ψ φ yields a value of the CP violating phase of −0.44 ± 0.44 ± 0.02 rad, consistent with the Standard Model expectation.