The ratio of the Λ0b baryon lifetime to that of the Bbar0 meson is measured using 1.0 fb−1 of integrated luminosity in 7 TeV center-of-mass energy pp collisions at the LHC. The Λ0b baryon is observed for the first time in the decay mode Λ0b→J/ψpK−, while the Bbar0 meson decay used is the well known Bbar0→J/ψπ+K− mode, where the π+K− mass is consistent with that of the Kbar*0(892) meson. The ratio of lifetimes is measured to be 0.976±0.012±0.006, in agreement with theoretical expectations based on the heavy quark expansion. Using previous determinations of the Bbar0 meson lifetime, the Λ0b lifetime is found to be 1.482±0.018±0.012 ps. In both cases, the first uncertainty is statistical and the second systematic.
Precision Measurement of the Λ0b Baryon Lifetime
CARDINALE, ROBERTA;FONTANELLI, FLAVIO;PATRIGNANI, CLAUDIA;PETROLINI, ALESSANDRO;SANNINO, MARIO;
2013-01-01
Abstract
The ratio of the Λ0b baryon lifetime to that of the Bbar0 meson is measured using 1.0 fb−1 of integrated luminosity in 7 TeV center-of-mass energy pp collisions at the LHC. The Λ0b baryon is observed for the first time in the decay mode Λ0b→J/ψpK−, while the Bbar0 meson decay used is the well known Bbar0→J/ψπ+K− mode, where the π+K− mass is consistent with that of the Kbar*0(892) meson. The ratio of lifetimes is measured to be 0.976±0.012±0.006, in agreement with theoretical expectations based on the heavy quark expansion. Using previous determinations of the Bbar0 meson lifetime, the Λ0b lifetime is found to be 1.482±0.018±0.012 ps. In both cases, the first uncertainty is statistical and the second systematic.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.