A measurement of $$\Lambda _c^ + $$ baryon production in proton-proton interactions at $$\sqrt s = 62GeV$$

Abstract

The production of open charm has been studied in proton-proton interactions at\(\sqrt s = 62GeV\). We report on the observation of the charmed baryon\(\Lambda _c^ + \), in coincidence with an electron from the associated anticharm decay, via the reaction\(p + p \to e^ - + \Lambda _c^ + + X\), in the kinematical region defined by |xF|≅0 andpt>0.5 GeV/c for the e−, and |xF|>0.35 for the\(\Lambda _c^ + \). The longitudinal and transverse momentum distributions of the\(\Lambda _c^ + \) have been derived. The cross-section for\(\bar D\Lambda _c^ + \) associated production has been estimated extrapolating to the full phase space the observed production distributions. The suppression factor with respect to\(\Lambda _s^0 \) production, at ISR energies, turns out to be about 1/50 in the high-|xF| range. The results confirm that the «leading» particle effect dominates baryon production in proton-proton interactions.