Observation of the decay

摘要

The decayΛb0→Λc+pp￣π?is observed usingppcollision data collected with the LHCb detector at centre-of-mass energies ofs=7and 8 Tev, corresponding to an integrated luminosity of 3?fb?1. The ratio of branching fractions betweenΛb0→Λc+pp￣π?andΛb0→Λc+π?decays is measured to beB(Λb0→Λc+pp￣π?)B(Λb0→Λc+π?)=0.0540±0.0023±0.0032.Two resonant structures are observed in theΛc+π?mass spectrum of theΛb0→Λc+pp￣π?decays, corresponding to theΣc(2455)0andΣc?(2520)0states. The ratios of branching fractions with respect to the decayΛb0→Λc+pp￣π?areB(Λb0→Σc0pp￣)×B(Σc0→Λc+π?)B(Λb0→Λc+pp￣π?)=0.089±0.015±0.006,B(Λb0→Σc?0pp￣)×B(Σc?0→Λc+π?)B(Λb0→Λc+pp￣π?)=0.119±0.020±0.014.In all of the above results, the first uncertainty is statistical and the second is systematic. The phase space is also examined for the presence of dibaryon resonances. No evidence for such resonances is found.