A. Airapetian et al., Multiplicity of charged and neutral pions in deep-inelastic scattering of 27.5 GeV positrons on hydrogen, EUR PHY J C, 21(4), 2001, pp. 599-606
Measurements of the individual multiplicities of pi (+), pi (-) and pi (0)
produced in thc deep-inelastic scattering of 27.5 GeV positrons on hydrogen
are presented. The average charged pion multiplicity is the same as for ne
utral pions, up to z approximate to 0.7, where z is the fraction of the ene
rgy transferred in the scattering process carried by the pion. This result
(below z approximate to 0.7) is consistent with isospin invariance. The tot
al 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.), respe
ctively. For fixed z, the measured multiplicities depend oil both the negat
ive squared four momentum transfer Q(2) and the Bjorken variable x. The obs
erved dependence oil Q(2) agrees qualitatively with the expected behaviour
based oil NLO-QCD evolution, while, the dependence on x is consistent with
that of previous data after corrections have been made for the expected Q(2
)-dependence.