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Regular version of the site

Article

Study of charmonium production in b-hadron decays and first evidence for the decay B0s→ϕϕϕ

The European Physical Journal C - Particles and Fields. 2017. Vol. 77. No. 9. P. 609-626.

Using decays to ϕ-meson pairs, the inclusive production of charmonium states in b-hadron decays is studied with pp collision data corresponding to an integrated luminosity of 3.0fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by BC≡B(b→CX)×B(C→ϕϕ) the inclusive branching fraction of a b hadron to a charmonium state C that decays into a pair of ϕ mesons, ratios RC1C2≡BC1/BC2 are determined as Rχc0ηc(1S)=0.147±0.023±0.011, Rχc1ηc(1S)=0.073±0.016±0.006, Rχc2ηc(1S)=0.081±0.013±0.005, Rχc1χc0=0.50±0.11±0.01, Rχc2χc0=0.56±0.10±0.01 and Rηc(2S)ηc(1S)=0.040±0.011±0.004. Here and below the first uncertainties are statistical and the second systematic. Upper limits at 90% confidence level for the inclusive production of X(3872), X(3915) and χc2(2P) states are obtained as RX(3872)χc1<0.34, RX(3915)χc0<0.12 and Rχc2(2P)χc2<0.16. Differential cross-sections as a function of transverse momentum are measured for the ηc(1S) and χc states. The branching fraction of the decay B0s→ϕϕϕ is measured for the first time, B(B0s→ϕϕϕ)=(2.15±0.54±0.28±0.21B)×10−6. Here the third uncertainty is due to the branching fraction of the decay B0s→ϕϕ, which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse ϕ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the ηc(1S) decays to ϕϕ and pp¯ as B(ηc(1S)→ϕϕ)/B(ηc(1S)→pp¯)=1.79±0.14±0.32.