Measurement of inclusive pi(0) production in hadronic Z(0) decays

An analysis is presented of inclusive pi(0) production in Z(0) decays measured with the DELPHI detector, At low energies, pi(0) decays are reconstructed by using pairs of converted photons and combinations of converted photons and photons reconstructed in the: barrel electromagnetic calorimeter (HPC). At high energies (up to x(p) = 2 . p(pi)/root s = 0.75) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers, The inclusive differential cross section is measured as a function of energy for q (q) over bar and b (b) over bar events, The number of pi(0)'s per hadronic Z(0) event is N(pi(0))/Z(had)(0) = 9.2 +/- 0.2(stat) +/- 1.0(syst) and for b (b) over bar events the number of pi(0),s is N(pi(0))/b (b) over bar = 10.1 +/- 0.4(stat) +/- 1.1(syst). The ratio of the number of pi(0)'s in b (b) over bar events to hadronic Z(0) events is less affected by the systematic errors and is found to be 1.09 +/- 0.05 +/- 0.01. The measured pi(0) cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the xi(p) = ln(l/X(p)) distribution is xi(p)* = 3.90(-0.14)(+0.24). The average number of pi(0)'s from the decay of primary B hadrons is found to be N(B --> pi(0) X)/B hadron = 2.78 +/- 0.15(stat) +/- 13.60(syst).