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Measurement of inclusive π 0 production in hadronic Z 0 decays

par Adam, Wolfgang;Bertrand, Daniel ;Bricman, Charles ;Cao, Futian;Deghorain, A.;De Boeck, Hugo;De Brabandere, S.;De Clercq, Catherine;Herquet, Philippe ;Hoorelbeke, S.;Huet, Kathy;Lefebure, Véronique ;Lemonne, Jacques ;Maocun, C.;Tomaradze, A.;Vander Velde, Catherine ;Van Doninck, Walter;Verbeure, F;Wickens, John H. ; [et al.]
Référence Zeitschrift für Physik. C, Particles and fields, 69, 1, page (561-573)
Publication Publié, 1995-12

Article révisé par les pairs

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Résumé :

An analysis is presented of inclusive π 0 production in Z 0 decays measured with the DELPHI detector. At low energies, π 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 {Mathematical expression}) 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 qq and bb events. The number of π 0's per hadronic Z 0 event is N(π 0)/Z had 0 =9.2±0.2(stat)±1.0(syst) and for bb events the number of π 0's is N(π 0)/bb=10.1±0.4(stat)±1.1(syst). The ratio of the number of π 0's in bb 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 π 0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the ξ p=ln(1/xp) distribution is ξ* p =3.90 -0.14 +0.24 . The average number of π 0's from the decay of primary B hadrons is found to be N(B→π 0 X)/B hadron=2.78±0.15(stat)±0.60(syst). © 1996 Springer-Verlag.