Measurement of the time-dependent CP asymmetries in Bs0→ J/ψKS0

The LHCb Collaboration

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The first measurement of decay-time-dependent CP asymmetries in the decay B0s → J/ψK0S and an updated measurement of the ratio of branching fractions B(B0s → J/ψK0S)/B(B0 → J/ψK0S) are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb−1 of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The results on the CP asymmetries are
A∆Γ(B0s → J/ψK0S) = 0.49 ±0.770.65 (stat) ± 0.06(syst),
Cdir(B0s → J/ψK0S) = −0.28 ± 0.41(stat) ± 0.08(syst),
Smix(B0s → J/ψK0S) = −0.08 ± 0.40(stat) ± 0.08(syst).

The ratio B(B0s → J/ψK0S)/B(B0 → J/ψK0S) is measured to be
0.0431 ± 0.0017(stat) ± 0.0012(syst) ± 0.0025(fs/fd), where the last uncertainty is due to the knowledge of the B0s and B0 production fractions.
Original languageEnglish
Article number131
Number of pages22
JournalJournal of High Energy Physics
Issue number6
Publication statusPublished - 2015
Externally publishedYes


  • CP violation
  • Hadron-Hadron Scattering
  • Branching fraction
  • B physics
  • Flavor physics

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