5 research outputs found

    Search for neutral heavy leptons produced in Z decays

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    Weak isosinglet Neutral Heavy Leptons (nu(m)) have been searched for using data collected by the DELPHI detector corresponding to 3.3 x 10(6) hadronic Z(0) decays at LEP1. Four separate searches have been performed, for short-lived nu(m) production giving monojet or acollinear jet topologies, and for long-lived nu(m) giving detectable secondary vertices or calorimeter clusters, No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z(0) –> nu(m)<(nu)over bar>) of about 1.3 x 10(-6) at 95% confidence level for nu(m) masses between 3.5 and 50 GeV/c(2). Outside this range the limit weakens rapidly with the nu(m) mass. The results are also interpreted in terms of Limits for the single production of excited neutrinos

    Charged particle multiplicity in e(+)e(-) interactions at root s=130 GeV

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    From the data collected by DELPHI at LEP in autumn 1995, the multiplicity of charged particles at a hadronic energy of 130 GeV has been measured to be [n(ch)] = 23.84 +/- 0.51(stat) +/- 0.52(syst), When compared to lower energy data, the value measured is consistent with the evolution predicted by QCD with corrections at next-to-leading order, for a value alpha(s) (130 GeV) = 0.105 +/- 0.003(stat) +/- 0.008(syst)
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