Study Of B_s⁰→J/Ψη And B_s⁰→J/Ψω Decays At LHCb

The two-body decays of B meson into a charmonium resonance J/Ψ and a light meson η,η’,ω or are color-suppressed b→ccs or b→ccd processes.Precise measurement of their branching fractions can shed light on η-η’ mixing and ω-Φmixing,and pave the way for study of CP violation in these decays.With the full dataset collected by LHCb in 2015-2018,the branching fractions of B0→J/Ψω and B(s)0→ J/Ψη decays are updated.A search for Bs0→ J/Ψω decay is also performed.Based on simulation samples,we use multivariate technique to opti-mize the event selection criteria aiming for effective suppression of the background.The branching fractions are measured to be:B(B0→ J/Ψη)=(1.26±0.13(stat)±0.11(syst))×10-5,B(Bs0→J/Ψη)=(4.05±0.16(stat)±0.23(syst))×10-4,B(B0→J/Ψω)=(2.41±0.12(stat)±0.16(syst))×10-5,which are more precise than the previous LHCb measurements.An evidence ofBs0→J/Ψω is found,and its branching fraction is estimated:B(Bs0→J/Ψω)=(7.17±1.40(stat)±1.19(syst))× 10-6。The ratio of the branching fractions of B0→J/Ψη and B(s)0)→J/Ψη is determined to be:#12Finally the η-η’ mixing angle is determined to be Φp=(42.3±1.7)° using this estimate of Rη.