Showing papers by "Tohru Takeshita published in 1986"
TL;DR: In this article, the authors compared 2nd-order QCD calculations with 3-and 4-jet models in the energy range of 14.0-46.7 GeV and showed that the observed excess of spherical events can partially be explained by the production of multi-parton events expected from higher order QCD contributions.
Abstract: Hadronic jet production bye+e−-annihilation has been studied in the energy range of 14.0–46.7 GeV. The data have been analysed in terms of a cluster algorithm and other topological quantities. The results are compared with 2nd order QCD calculations which incorporate models for the fragmentation of quarks and gluons into hadrons. At the higher energies we observe more spherical and 4-jet like events than predicted by these calculations. We cannot achieve a simultaneous description of the observed 3- and 4-jet production by adjusting the strong coupling constant αs or the fragmentation parameters of the 2nd order QCD models. The observed excess of spherical events can partially be explained by the production of multi-parton events expected from higher order QCD contributions. Consequences of the presented results for the value of αs, determined in previous analyses, are discussed. QCD parton shower models, including soft gluon interference, are able to describe the observed number of spherical events.
292 citations
TL;DR: In this paper, an analysis of the three leptonic reactionse+e−→e−e−,μ+μ− andτ+τ− over a wide range of energy is presented, and the axial-vector and vector weak coupling constant, sin2θW andMZ are determined and compared to other measurements.
Abstract: An analysis of the three leptonic reactionse+e−→e+e−,μ+μ− andτ+τ− over a wide range of energy,\(12< \sqrt s< 46.78 GeV\) is presented. The data were obtained with the JADE detector at thee+e− storage ring PETRA. They are compared to predictions of electroweak theories, in particular the standard model. For the total cross-sections of all three reactions and for the differential cross-section of Bhabha scattering no deviation from QED is found over the entire energy range. The differential cross-sections of μ and τ pairs at high energies show the angular asymmetry predicted by electroweak interference. The axial-vector and vector weak coupling constant, sin2θW andMZ are determined and compared to other measurements. Finally, limits on deviations from the standard model are given.
17 citations
TL;DR: In this paper, the lifetime of B-hadrons produced ine+e− annihilation into multihadronic final states was determined by measuring the impact parameter of the track with respect to the center of the interaction region.
Abstract: We have determined the lifetime ofB-hadrons produced ine+e− annihilation into multihadronic final states, by measuring the impact parameter of the track with respect to the centre of the interaction region. Two different analyses of the data were performed and gave compatible results. The lifetime is τB=1.8−0.4+0.5±0.4 ps.
12 citations
TL;DR: In this paper, a study of radiative τ pair production, e+e−→τ+τ−γ ande+e −→τ +τ+γγ, is presented, and lower limits on single and pair production are obtained.
Abstract: A study of radiative τ pair production,e+e−→τ+τ−γ ande+e−→τ+τ−γγ, is presented. The observed events agree with QED predictions of order α3 and α4. Excited τ′s have been searched for and lower limits on single and pair production are obtained. For QED-like coupling the τ* mass is limited to values greater than 40 GeV (95% CL). A search for unstable charged scalars (S±) decaying into τ, e.g. charged Higgs, technipions or the supersymmetric partners of τ′s, yields no evidence for such particles. Assuming a branching fraction ofB(S→τν)=1,S masses up to 18.7 GeV are excluded with 95% CL.
11 citations
TL;DR: The total and differential cross sections for exclusive production of proton-antiproton pairs in photon-photon collisions have been measured using the JADE detector at PETRA.
10 citations
TL;DR: In this article, the JADE detector at PETRA was used to detect lepton pair production by two-photon processes using the endcap or barrel shower counters, and the observed events consist of two produced leptons as well as two tagged electrons.
Abstract: Lepton pair production by two-photon processes has been studied using the JADE detector at PETRA The study probed QED to α4 in the highestQ
2 region Both electrons and positrons were tagged by the endcap or barrel shower counters The observed events consist of two produced leptons as well as two tagged electrons These events show good agreement with QED to order α4
9 citations
TL;DR: In this article, the cross-section power ratio in this model is found to be independent of incident energy, lab angle and target mass, being a universal function of the final particle momentum only.
8 citations
4 citations