Measurement of hadron and lepton-pair production at 161 GeV<root s<172 GeV at LEP

Contains fulltext : 26256.pdf (publisher's version ) (Open Access

A Measurement of Pi-Polarization at Lep

Contains fulltext : 26223.pdf (publisher's version ) (Open Access

Measurement of hadron and lepton-pair production at 130 GeV<root s<140 GeV at LEP

Contains fulltext : 26240.pdf (publisher's version ) (Open Access

Measurement of Eta(C) Production in Untagged 2-Photon Collisions at Lep

Contains fulltext : 26838___.PDF (publisher's version ) (Open Access

A measurement of τ\tau polarization at LEP

With a data sample of 86 000 Z → τ+τ-(γ) events collected in 1990 through 1993 we have measured the polarization of τ-leptons as a function of the production polar angle using the following 1-prong τ decay modes: τ-→e-vevτ, τ-→π- (K-)vτ, τ-→ρ{variant}-vτ and τ-→a1-vτ. We obtain for the ratio vector to axial-vector weak neutral couplings for electrons gVe/gAe=0.0791±0.0099(stat)±0.0025 (syst) and taus gVτ/gAτ=0.0752±0.0063 (stat)±0.0045 (syst) consistent with the hypothesis of e - τ universality. Assuming universality of the e - τ neutral current we determine the effective electroweak mixing angle to be sin2 θeffw = 0.2309 ± 0.0016. © 1994

Inclusive J, Psi' and Chi(c) production in hadronic Z decays

We report on measurements of the inclusive production of J, psi' and chi(c) mesons in hadronic Z decays, based on 3.2 million hadronic events collected using the L3 detector at LEP. The J and psi' mesons are reconstructed through their decays into lepton pairs, while the chi(c) mesons are reconstructed via the decay mode chi(c) --> J + gamma. The measured branching fractions are: Br(Z --> J + X) = (3.40 +/- 0.23 (stat.) +/- 0.27 (sys.)) x 10(-3), Br(Z --> psi' + X) = (1.6 +/- 0.5 (stat.) +/- 0.3 (sys.)) x 10(-3) Br(Z --> chi(cl) + X) = (2.7 +/- 0.6 (stat.) +/- 0.5 (sys.)) x 10(-3). In the absence of a clear chi(c2) signal, the upper limit at 90% C.L. is set: Br(Z --> chi(c2) + X) < 3.2 x 10(-3). (C) 1997 Elsevier Science B.V

Study of hadronic events and measurements of alpha(s) between 30 and 91 GeV RID C-4549-2008 RID C-5719-2008

We have studied the structure of hadronic events with a hard, isolated photon in the final state (e(+)e(-) --> Z --> hadrons + gamma) in the 3.6 million hadronic events collected with the L3 detector at centre-of-mass energies around 91 GeV. The centre-of-mass energy of the hadronic system is in the range 30 GeV to 86 GeV. Event shape variables have been measured at these reduced centre-of-mass energies and have been compared with the predictions of different QCD Monte Carlo programs. The event shape variables and the energy dependence of their mean values are well reproduced by QCD models. We fit distributions of several global event shape variables to resummed O/alpha(s)(2)/calculations to determine the strong coupling constant a, over a wide range of energies. We find that the strong coupling constant alpha(s) decreases with increasing energy, as expected from QCD. (C) 1997 Elsevier Science B.V