A comparison of two-particle rapidity correlations in antiproton-proton and proton-proton interactions at 31 GeV centre-of-mass energy

We investigated correlations between pairs of charged secondaries produced in antiproton-proton and proton-proton interactions at a centre-of-mass energy of 31 GeV using the pseudorapidity variable eta=-ln(than theta/2). Positive, short-range correlations were observed in both reactions. In the antiproton-proton case, however, there is a stronger correlation at very short range when both particles are produced in the central region and when the charged multiplicity of the event is about 30% higher than the mean. A simple Monte Carlo calculation indicates that quark-antiquark annihilation into two hadronic jets could account for the observed effect. (orig.)