Charged-particle multiplicity distributions inνnandνpcharged-current interactions

Abstract

Charged-hadron multiplicity distributions in $\ensuremath{\nu}n$ and $\ensuremath{\nu}p$ interactions are measured in an exposure of the Fermilab deuterium-filled 15-foot bubble chamber to a wide-band neutrino beam. Multiplicity moments are studied as functions of the invariant mass of the hadronic system $W$ in the range $1lWl15$ GeV. The mean multiplicities for both $\ensuremath{\nu}n$ and $\ensuremath{\nu}p$ are found to increase logarithmically with ${W}^{2}$ with identical slopes but slightly different intercepts. A linear rise of the dispersion $D$ with the mean multiplicity $〈{n}_{\mathrm{ch}}〉$ is observed with an approximate slope of 0.35. This value is similar to that found in ${e}^{+}{e}^{\ensuremath{-}}$ and $\overline{p}p$ annihilation and is much less than the asymptotic prediction of QCD. A close similarity between ${D}_{\ensuremath{-}}$ vs $〈{n}_{\ensuremath{-}}〉$ in $\ensuremath{\nu}n$ and $\ensuremath{\nu}p$ interactions is seen. Negative correlations between the multiplicity distributions in the forward and backward hadronic center-of-mass hemispheres are found and discussed.