Measurement of V 0 production ratios in pp collisions at ps = 0.9 and 7TeV

Abstract

The Λ¯/Λ and Λ¯/K0S production ratios are measured by the LHCb detector from 0.3 nb−1 of pp collisions delivered by the LHC at s√=0.9 TeV and 1.8 nb−1 at s√=7 TeV. Both ratios are presented as a function of transverse momentum, p T, and rapidity, y, in the ranges 0.15 < p T < 2.50 GeV/c and 2.0 < y < 4.5. Results at the two energies are in good agreement as a function of rapidity loss, ∆y = y beam − y, and are consistent with previous measurements. The ratio Λ¯/Λ, measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted in simulation, particularly at high rapidity. The ratio Λ¯/K0S, measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected.