Guy Wilkinson

Abstract:

The LHC-B Level-1 trigger will consist of high p(t) muon, electron and hadron components. The requirements at Level-1 are discussed and the algorithms and performances of these sub-triggers described. A possible running scenario is explored and the consequent signal efficiencies and trigger rates are given.

Abstract:

The hadronic photon structure function F2γ has been measured in the Q2 range from 4 to 30 GeV2/c4 and down to x values of order 0.001, using data taken with the DELPHI detector at LEP between 1991 and 1993. A comparison is made with several F2γ parameterizations with special emphasis on their low x behaviour. A result on the Q2 evolution of F2γ is presented. © Springer-Verlag 1996.

Abstract:

The hadronic photon structure function F 2 γ has been measured in the Q 2 range from 4 to 30 GeV 2 /c 4 and down to x values of order 0.001, using data taken with the DELPHI detector at LEP between 1991 and 1993. A comparison is made with several F 2 γ parameterizations with special emphasis on their low x behaviour. A result on the Q 2 evolution of F 2 γ is presented. © 1996 Springer-Verlag.

Abstract:

An analysis is reported on the channel e⁺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: {Mathematical expression} © 1995 Springer-Verlag.

Abstract:

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.