Measurements of the individual multiplicities of π+, π- and π0 produced in the deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged pion multiplicity is the same as for neutral pions, up to z ≈ 0.7, where z is the fraction of the energy transferred in the scattering process carried by the pion. This result (below z ≈ 0.7) is consistent with isospin invariance. The total energy fraction associated with charged and neutral pions is 0.51 ± 0.01(stat.) ± 0.08(syst.) and 0.26 ± 0.01(stat.) ± 0.04(syst.), respectively. For fixed z, the measured multiplicities depend on both the negative squared four momentum transfer Q2 and the Bjorken variable χ. The observed dependence on Q2 agrees qualitatively with the expected behaviour based on NLO-QCD evolution, while the dependence on χ is consistent with that of previous data after corrections have been made for the expected Q2-dependence.
ASJC Scopus subject areas
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)