2025/08/13 by ALICE Collaboration
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2508.09955
The first measurement at midrapidity (|y| < 0.5) of the production yield of the strange-charm baryons Ξc+ and Ξc0 as a function of charged-particle multiplicity in proton-proton collisions at √(s) = 13 TeV with the ALICE experiment at the LHC is reported. The Ξc+ baryon is reconstructed via the Ξc+ → Ξ-π+π+ decay channel in the range 4 < p\rm T < 12 GeV/c, while the Ξc0 baryon is reconstructed via both the Ξc0 → Ξ-π+ and Ξc0 → Ξ-e+νe decay channels in the range 2 < p\rm T < 12 GeV/c. The baryon-to-meson (Ξc0,+/D0) and the baryon-to-baryon (Ξc0,+/Λc+) production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at e+e- and e-p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed. Moreover, the branching-fraction ratio of BR(Ξc0 → Ξ-e+νe)/BR(Ξc0 → Ξ-π+) is measured as 0.825 ± 0.094 (stat.) ± 0.081 (syst.). This value supersedes the previous ALICE measurement, improving the statistical precision by a factor of 1.6.