Multiplicity distributions in anti ν-/sub μ/p interactions

Multiplicity distributions of the hadrons produced in antineutrino proton interactions are presented. The data sample, which consists of 2025 charged-current events with antineutrino energy greater than 5 GeV, comes from exposures of the 15-foot hydrogen bubble chamber to the broad-band antineutrino beam at Fermilab. The distribution in hadronic mass W has an average value of 3.7 GeV but extends up to 10 GeV. The mean multiplicity of charged hadrons depends on the hadronic mass W and varies as = (-0.44 +- 0.13) + (1.48 +- 0.06) 1n W2 for W2 > 4 GeV2. The mean multiplicities for events with three or more charged tracks averaged over the total data sample are = 1.68 +-0.03 and = 1.11 +- 0.07 for π- and π0 production, respectively. The mean π0 multiplicity is found to increase slowly with n/sub -/. The integrated correlation coefficient f2-- and the dispersion D- are given as a function of n/sub -/. When compared to the distributions characteristic of other leptonic and hadronic reactions, a similarity is found between the anti ν- data and results from hadronic reactions that have no diffractive component. Multiplicity data for the heavier particles K0, rho and Λ are also summarized. The pion multiplicities in the current fragmentation region exceed those for the target fragmentation at all W values. They also satisfy the isospin relation 2 = + required for the fragmentation of an I = 1/2 quark when a W > 4 GeV selection is imposed