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Multiplicity of charged and neutral pions in deep-inelastic scattering of 27.5 GeV positrons on hydrogen

Abstract.

Measurements of the individual multiplicities of \(\pi^+, \pi^-\) and \(\pi^0\) 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 \(z \approx 0.7\), where z is the fraction of the energy transferred in the scattering process carried by the pion. This result (below \(z \approx 0.7\)) is consistent with isospin invariance. The total energy fraction associated with charged and neutral pions is \(\rm 0.51 \pm 0.01 (stat.) \pm 0.08\) (syst.) and \(\rm 0.26 \pm 0.01 (stat.) \pm 0.04 (syst.)\), respectively. For fixed z, the measured multiplicities depend on both the negative squared four momentum transfer \(Q^2\) and the Bjorken variable x. The observed dependence on \(Q^2\) agrees qualitatively with the expected behaviour based on 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.

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Received: 2 April 2001 / Revised version: 27 June 2001 / Published online: 7 September

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The HERMES Collaboration., Airapetian et al., A. Multiplicity of charged and neutral pions in deep-inelastic scattering of 27.5 GeV positrons on hydrogen. Eur. Phys. J. C 21, 599–606 (2001). https://doi.org/10.1007/s100520100765

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  • DOI: https://doi.org/10.1007/s100520100765

Keywords

  • Hydrogen
  • Total Energy
  • Momentum Transfer
  • Energy Fraction
  • Neutral Pion