Measurement of the CP-violating phase Φs in B0s → J/ψπ+π- decays

Abstract

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.