Measurement of the mixing-induced CP-violating phase Φs in B0s decays is of prime importance in probing new physics. Here 7421 ± 105 signal events from the dominantly CP-odd final state J/ψπ+π- are selected in 1 fb-1 of pp collision data collected at √ s = 7 TeV with the LHCb detector. A timedependent fit to the data yields a value of Φs = -0.019+0.173+0.004-0.174-0.003 rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found.
Aaij, R., Abellan Beteta, C., Adeva, B., Adinolfi, M., Adrover, C., Affolder, A., … Zvyagin, A. (2012). Measurement of the CP-violating phase Φs in B0s → J/ψπ+π- decays. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 713(4–5), 378–386. https://doi.org/10.1016/j.physletb.2012.06.032