ATLAS

Abstract:

In a bubble chamber experiment with BEBC the spin alignment parameter η= 1 2 (2ρ{variant}00 - ρ{variant}11 - ρ{variant}-1-1) is measured for ρ{variant}0 mesons produced in deep inelastic charged-current antineutrino and neutrono interactions on neon. In the current fragmentation region η is found to be ηv=0.48±0.27 (stat.)±0.15 (syst.) for vNe and ηv=0.12±0.20 (stat.)±0.10 (syst.) for vNe interactions. © 1987.

Abstract:

A study has been made of the decays W → ev and Z → e+e-, using the UA2 detector at the CERN p̄p Collider. The data correspond to an integrated luminosity of 142 nb-1 at a centre-of-mass collision energy √s=546 GeV, and 768 nb-1 at √s=630 GeV. Measurements of the standard model parameters from samples of 251 W decay and 39 Z decay candidates are compared with expectations of the standard electroweak model. © 1987.

Abstract:

The invariant mass distribution of jet pairs observed in the UA2 central calorimeter is examined in the search for an excess of events in the region of the W± and Z bosons, which would reveal their decays into quark-antiquark pairs. We give a detailed account of the methods of analysis used to optimize the mass resolution achieving ≅±10%. A structure is observed at the level of ≅ 3 standard deviations in the mass region of W± and Z with shape and position consistent with expectation from their qq̄decays. It contains 632 ± 190 events, 1.4 standard deviations above the standard model prediction of 340 ± 80 events. © 1987.

Abstract:

The isoscalar nucleon structure functions F2(x, Q²) and xF3(x, Q²) are measured in the range 02<64 GeV², 1.72<250 GeV², x<0.7 using ν and {Mathematical expression} interactions on neon in BEBC. The data are used to evaluate possible higher twist contributions and to determine their impact on the evaluation of the QCD parameter Λ. In contrast to previous analyses reaching to such low W² values, it is found that a low {Mathematical expression} value in the neighbourhood of 100 MeV describes the data adequately and that the contribution of dynamical higher twist effects is small and negative. © 1987 Springer-Verlag.