Correlated /\c-/\cbar production in e+e- annihilations at sqrt{s}~10.5 GeV

TL;DR

This study investigates baryon number correlations in e+e- annihilation events at 10.5 GeV, revealing a significant enhancement in correlated \/c+ and \/c- production compared to meson correlations, challenging existing Monte Carlo models.

Contribution

It provides the first measurement of primary baryon-baryon correlations in e+e- collisions at this energy, highlighting discrepancies with standard simulation predictions.

Findings

+ and - baryons are more likely to be produced opposite each other than + and Dbar mesons.

The observed correlation exceeds predictions from the JETSET 7.3 Monte Carlo simulation.

The likelihood ratio of + opposite - versus Dbar is approximately 3.5.

Abstract

Using 13.6/fb of continuum two-jet e+e- -> ccbar events collected with the CLEO detector, we have searched for baryon number correlations at the primary quark level. We have measured the likelihood for a /\c+ charmed baryon to be produced in the hemisphere opposite a /\c- relative to the likelihood for a /\c+ charmed baryon to be produced opposite an anticharmed meson Dbar; in all cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We find that, given a /\c- (reconstructed in five different decay modes), a /\c+ is observed in the opposite hemisphere (0.72+/-0.11)% of the time (not corrected for efficiency). By contrast, given a Dbar in one hemisphere, a /\c+ is observed in the opposite hemisphere only (0.21+/-0.02)% of the time. Normalized to the total number of either /\c- or Dbar ``tags'', it is therefore 3.52+/-0.45+/-0.42 times more likely to find a /\c+ opposite a /\c- than a Dbar meson. This enhancement is not observed in the JETSET 7.3 e+e- -> ccbar Monte Carlo simulation.