Abstract
The decay Λb0→Λc+pp‾π− is observed using pp collision data collected with the LHCb detector at centre-of-mass energies of s=7 and 8 Tev, corresponding to an integrated luminosity of 3 fb−1. The ratio of branching fractions between Λb0→Λc+pp‾π− and Λb0→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 the Λc+π− mass spectrum of the Λb0→Λc+pp‾π− decays, corresponding to the Σc(2455)0 and Σc⁎(2520)0 states. The ratios of branching fractions with respect to the decay Λb0→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.
Highlights
The quark model of Gell-Mann [1] and Zweig [2] classifies mesons and baryons into multiplets, and allows for hadrons with more than the minimal quark contents
A measurement is made of its branching fraction relative to the normalisation channel Λb0 → Λc+π −
Selection requirements can be made on the trigger selection itself and on whether the decision was due to the reconstructed candidate decay, other particles produced in the pp collision, or a combination of the two
Summary
The quark model of Gell-Mann [1] and Zweig [2] classifies mesons (qq) and baryons (qqq) into multiplets, and allows for hadrons with more than the minimal quark contents. In the decay channel Λb0 → Λc+ p pπ −,1 charmed dibaryon resonant states could be present. The discovery of any of these decay modes would test the predictions of quantum chromodynamics and the fundamental workings of the Standard Model. In this Letter, the first observation of the decay Λb0 → Λc+ p pπ −, referred to as the signal channel, is reported. A measurement is made of its branching fraction relative to the normalisation channel Λb0 → Λc+π −. Σc∗(2520)0 resonances are found in the Λc+π − invariant mass spectrum. The ratios of branching fractions between decays via these resonances, hereinafter denoted as Σc0 and Σc∗0, and the.
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