M. S. Bilenky

Analytic approach to the complete set of QED corrections to fermion pair production in e + e - annihilation

We present the convolution integral for fermion pair production in the electroweak standard theory to order O(α) including also soft photon exponentiation. The result is complete in the sense that it includes initial- and final-state radiation and their interference. From the basic result — analytic formulae for the differential cross section — we also derive the corresponding expressions for the total cross section σT and the integrated forward-backward asymmetry AFB. The numerical importance of different contributions for the analysis of experiments at LEP/SLC energies is discussed.

QED corrections with partial angular integration to fermion pair production in e+ e- annihilation

Abstract Analytic formulae are derived for the complete photon energy spectrum due to QED corrections to fermion pair production in the case of a limited angular acceptance for the final state fermions. After a numerical integration over the energy of non-observed photons, this corresponds to typical experimental conditions at LEP/SLC.

The convolution integral for the forward-backward asymmetry in e+e− annihilation

Abstract The complete convolution integral for the forward-backward asymmetry AFB in e+e− annihilation is obtained in order O (α) with soft photon exponentiation. The influence of these QED corrections on AFB in the vicinity of the Z peak is discussed. The results are used to comment on a recent ad hoc ansatz using convolution weights derived for the total cross section.

Semi-analytical approach to four-fermion production in e+e− annihilation☆

A study of the semi-analytical approach to four-fermion production in e+e− annihilation is presented. We classify all possible four-fermion final states and present results of new calculations for the ‘basic’ processes with the WW, ZZ, and ZH off-shell production together with some examples of ‘background’ processes. The Initial State Radiative corrections are included for the basic processes. Several numerical examples are given in the energy range from LEP 2 up to s = 1 TeV.

Invisible width of the Z-boson and “secret” ν-ν interactions

Abstract The width of the decay Z→ν ν ν ν in the presence of a possible nonstandard four-fermion ν-ν interaction is calculated. From the invisible width of the Z-boson measured at LEP the upper bound on the strength F of such an effective interaction has been obtained: F≲4×102GF. This bound is about three orders of magnitude lower than earlier existing particle physics bounds and it is comparable with an estimate that can be obtained from supernova neutrino data. The expression for the spectrum of leptons in the decays W→lν l ν ν is also presented.

Scintillation hodoscopes for time-of-flight measurements

Abstract The performances of the TOF scintillation counters used in the SIGMA-AIAKS spectrometer are presented. The counters, made of NE110, are 150, 65 and 10 cm long, 10 cm wide and 1.5 cm thick. The time resolutions for minimum ionizing particles have been measured to be σ t = 0.18 ns, 0.14 ns and 0.11 ns respectively. The main contribution to the resolution is given by the photoe collection statistics determined by the decay time of the scintillator and the difference of the optical paths in the counter. The scintillation counters, assembled into hodoscopes of 1.5 × 3.2 m 2 and 0.65 × 0.8 m 2 are used for identification of particles through the TOF. The algorithms of off-line data processing are also presented.

Studies of the stability and systematics of operation of the Delphi plastic streamer tubes

The influence of different factors, such as pressure and temperature, slight changes in a gas mixture, self-sustaining discharge, aging and different deviations in the detector geometry, on the operation of the DELPHI plastic streamer tubes was studied. The contributions of these factors to the energy resolution of the DELPHI hadron calorimeter were estimated. The major influence was found to be due to atmospheric pressure fluctuations. The scale of a signal change is ∼±1% per ∓1 Torr, which is comparable with the intrinsic resolution of the hadron calorimeter of ∼8–10% at 100 GeV. The question of the choice of a gas mixture was studied as well. The maximum streamer charge was shown to be independent of component concentrations in the Ar:CO2:isobutane (or n-pentane) gas mixtures.

On the derivation of Standard Model Parameters from the Z Peak

The first complete calculation of electroweak radiative corrections (EWRC) in the standard theory /1/ for the reaction

Cross sections of backward proton production in 40 GeV/c π−(K−,p)−A interactions

{e^ + }{e^ - } \to \left( { \gamma , z} \right) \to {\mu ^ + }{\mu ^ - },