Showing papers by "Bjarne Stugu published in 1995"
TL;DR: In this article, an experimental evidence for the existence of orbitally excited B meson states is presented in an analysis of the Bπ and B∗π distribution of View the MathML source using Z0 decay data taken with the DELPHI detector at LEP.
61 citations
TL;DR: In this paper, an analysis on the channele+e−→μ+μ−(nγ), n=1,2..., using data taken with the DELPHI detector at LEP from 1990 to 1992, is presented.
Abstract: An analysis is reported on the channele+e−→μ+μ−(nγ), n=1,2..., using data taken with the DELPHI detector at LEP from 1990 to 1992. Differential cross sections of the radiative photons as a function of photon energy and of the angle between the photon and the muon are presented. No significant deviations from expectations are observed. The data are also used to extract the muon-pair cross section and asymmetry below the Z0 peak by using those events with relatively hard initial state radiative photon(s). The measured cross section and asymmetry show no significant deviation from the Standard Model expectations. These results together with the DELPHI cross section and asymmetry measurements at the LEP energies from the 1990 to 1992 running periods are used to determine limits on the Z0-Z′ gauge boson mixing angle θZ′ and on the Z′ mass. There is no indication of the existence of a Z′; the limits obtained on the mixing angle substantially improve upon existing limits. The 95% confidence level allowed ranges of θZ′ in various models are:
$$\begin{gathered} - 0.0070 \leqslant \theta _{Z'} \leqslant 0.0078,E_6 (\chi )\bmod el, \hfill \\ - 0.0075 \leqslant \theta _{Z'} \leqslant 0.0095,E_6 (\psi )\bmod el, \hfill \\ - 0.029 \leqslant \theta _{Z'} \leqslant 0.029,E_6 (\eta )\bmod el, \hfill \\ - 0.0068 \leqslant \theta _{Z'} \leqslant 0.0082,L - R(1.)\bmod el, \hfill \\ - 0.0057 \leqslant \theta _{Z'} \leqslant 0.0077,L - R(\sqrt 2 )\bmod el. \hfill \\ \end{gathered} $$
33 citations
TL;DR: In this paper, the DELPHI detector was used to measure three-particle correlations in e+e− annihilations at LEP using data collected by the DelphI detector.
26 citations
TL;DR: In this article, the authors measured the mean lifetimes of charged and neutral B hadrons using data collected by the DELPHI experiment at LEP between 1991 and 1993, and determined that the B+ and B0 meson lifetimes were 1.72±0.08 (stat.) ± 0.06 (syst.) ps and τB+ = 1.63± 0.14 (stat).
Abstract: The lifetimes of charged and neutral B hadrons have been measured using data collected by the DELPHI experiment at LEP between 1991 and 1993. B hadrons are tagged as jets with a secondary vertex and the charge of the B candidate is taken to be the sum of the charges of the particles in the secondary vertex. Approximately 1,434,000 multihadronic Z0 decays yielded 1817 B hadron candidates. The B purity was estimated to be around 99.1±0.3%, and 83% (70%) of the events measured as neutral (charged) came from neutral (charged) B's. The mean lifetimes of charged and neutral B hadrons were found to be 1.72±0.08 (stat.) ±0.06 (syst.) ps and 1.58±0.11 (stat.)±0.09 (syst.) ps respectively. The ratio of their lifertimes, τcharged/τneutral, was 1.09−0.10+0.11 (stat.)±0.08 (syst.). By making assumptions about the Bs0 and Λb0 states, the B+ and B0 meson lifetimes were determined to be τB+ = 1.72 ± 0.08 (stat.) ±0.06 (syst.) ps and τB+ = 1.63 ± 0.14 (stat.)±0.13 (syst.) ps and the ratio of their lifetimes was:
22 citations
TL;DR: The hadronic photon structure function F2γ has been measured in the Q2 range from 4 to 30 GeV2/c4 and down tox values of order 0.001, using data taken with DELPHI detector at LEP between 1991 and 1993.
Abstract: The hadronic photon structure functionF2γ has been measured in theQ2 range from 4 to 30 GeV2/c4 and down tox values of order 0.001, using data taken with the DELPHI detector at LEP between 1991 and 1993. A comparison is made with severalF2γ parameterizations with special emphasis on their lowx behaviour. A result on theQ2 evolution ofF2γ is presented.
1 citations