Baryon at Lep-1

A search for fully reconstructed Λ 0 b baryons was performed, using about 3.5 × 10 6 hadronic Z 0 decays acquired by the DELPHI detector at LEP-1. Two event candidates were found in the colour-suppressed decay channel J/ψΛ 0 , and four in the colour-allowed channels Λ + c π − /a − 1 , with an estimated background of 0.25 and 1.05 events, respectively. 1 Measurements of the Λ 0 b mass yield (5612.1 ± 21.2 stat ± 6.0 syst) MeV/c 2 and (5610 ± 24 stat ± 16 syst) MeV/c 2 , respectively, and are consistent with the world average value of the Particle Data Group [1].