Measurement of the CP-violating phase β in B[superscript 0] → [J over ψ π[superscript +] π[superscript -]] decays and limits on penguin effects

Abstract

Time-dependent CP violation is measured in the [(-) over B][superscript 0] → [J over ψ]π[superscript +]π[superscript −] channel for each π[superscript +]π[superscript −] resonant final state using data collected with an integrated luminosity of 3.0 fb[superscript −1] in pp collisions using the LHCb detector. The final state with the largest rate, [J over ψρ][superscript 0](770), is used to measure the CP -violating angle 2β[superscript eff] to be (41.7±9.6[superscript +2.8][subscript -6.3])°. This result can be used to limit the size of penguin amplitude contributions to CP violation measurements in, for example, [(-) over B][superscript 0] [subscript s] → [J over ψϕ] decays. Assuming approximate SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the CP-violating phase [subscript ϕs] is limited to be within the interval [−1.05°,+1.18°] at 95% confidence level. Changes to the limit due to SU(3) symmetry breaking effects are also discussed.