The first observation of the decays Λ_b^0→χ_c1pK^- and Λ_b^0→χ_c2pK^- is reported using a data sample corresponding to an integrated luminosity of 3.0 fb^-1, collected by the LHCb experiment in pp collisions at center-of-mass energies of 7 and 8 TeV. The following ratios of branching fractions are measured: B(Λ_b^0→χ_c1pK^-)/B(Λ_b^0→J/ψpK^-)=0.242±0.014±0.013±0.009,B(Λ_b^0→χ_c2pK^-)/B(Λ_b^0→J/ψpK^-)=0.248±0.020±0.014±0.009,B(Λ_b^0→χ_c2pK^-)/B(Λ_b^0→χ_c1pK^-)=1.02±0.10±0.02±0.05,where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the branching fractions of the χ_c1→J/ψγ and χ_c2→J/ψγ decays. Using both decay modes, the mass of the Λ_b^0 baryon is also measured to be m_Λ_b^0=5619.44±0.28±0.26 MeV/c^2, where the first and second uncertainties are statistical and systematic, respectively.
Observation of the Decays Λ_b^0→χ_c1pK^- and Λ_b^0→χ_c2pK^-
Veltri, M;
2017
Abstract
The first observation of the decays Λ_b^0→χ_c1pK^- and Λ_b^0→χ_c2pK^- is reported using a data sample corresponding to an integrated luminosity of 3.0 fb^-1, collected by the LHCb experiment in pp collisions at center-of-mass energies of 7 and 8 TeV. The following ratios of branching fractions are measured: B(Λ_b^0→χ_c1pK^-)/B(Λ_b^0→J/ψpK^-)=0.242±0.014±0.013±0.009,B(Λ_b^0→χ_c2pK^-)/B(Λ_b^0→J/ψpK^-)=0.248±0.020±0.014±0.009,B(Λ_b^0→χ_c2pK^-)/B(Λ_b^0→χ_c1pK^-)=1.02±0.10±0.02±0.05,where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the branching fractions of the χ_c1→J/ψγ and χ_c2→J/ψγ decays. Using both decay modes, the mass of the Λ_b^0 baryon is also measured to be m_Λ_b^0=5619.44±0.28±0.26 MeV/c^2, where the first and second uncertainties are statistical and systematic, respectively.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
