Journal of High Energy Physics > 2016 > 2016 > 5 > 1-22
Observation of Λ b 0 → ψ(2S)pK− and Λ b 0 → J/ψπ + π −pK− decays and a measurement of the Λ b 0 baryon mass
Source
Abstract
The decays Λ b 0 → ψ(2S)pK− and Λ b 0 → J/ψπ + π −pK− are observed in a data sample corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The ψ(2S) mesons are reconstructed through the decay modes ψ(2S) → μ+μ− and ψ(2S) → J/ψπ + π −.
The branching fractions relative to that of Λ b 0 → J/ψpK− are measured to be ℬ Λ b 0 → ψ 2 S p K − ℬ Λ b 0 → J / ψ p K − = 20.70 ± 0.76 ± 0.46 ± 0.37 × 10 − 2 , $$ \frac{\mathrm{\mathcal{B}}\left({\varLambda}_{\mathrm{b}}^0\to \psi \left(2\mathrm{S}\right){\mathrm{pK}}^{-}\right)}{\mathrm{\mathcal{B}}\left({\varLambda}_{\mathrm{b}}^0\to \mathrm{J}/\psi\;{\mathrm{pK}}^{-}\right)}=\left(20.70\pm 0.76\pm 0.46\pm 0.37\right)\times {10}^{-2}, $$ where the first uncertainties are statistical, the second are systematic and the third is related to the knowledge of J/ψ and ψ(2S) branching fractions. The mass of the Λ b 0 baryon is measured to be M Λ b 0 = 5619.65 ± 0.17 ± 0.17 M e V / c 2 , $$ M\left({\varLambda}_{\mathrm{b}}^0\right)=5619.65\pm 0.17\pm 0.17\ \mathrm{M}\mathrm{e}\mathrm{V}/{c}^2, $$ where the uncertainties are statistical and systematic.
Identifiers
journal e-ISSN : | 1029-8479 |
DOI | 10.1007/JHEP05(2016)132 |