(eng)
New results on inverse muon decay and coherent charged pion production by neutrinos are presented. The data come from the CHARM-II neutrino detector operated at the CERN wide-band neutrino beam. High-statistics data samples of 14500 inverse muon decay events and 3500 νμe elastic scattering events allow the determination of the electroweak parameters from the ratio of the cross-sections of neutral-to-charged-current neutrino electron scattering. The best fit values of the electroweak mixing angle and the relative coupling strength ϱ of neutral and charged current are:
.
In the second topic, coherent single charged pion production was measured in neutrino and antineutrino beams. The measured cross-sections, averaged over the wide-band beam spectra and the glass target nuclei composition, are: σ(νμA → μ−π+A) = (51 ± 10) × 10−40 cm2 nucleus and
nucleus. The energy dependence shows the expected flattering of the cross-sections at high energy.
Grégoire, G. ; Lemaitre, V. ; Knoops, E. ; Akkus, B. ; Favart, Denis ; et. al. New results on inverse muon decay and low multiplicity reactions. In: Nuclear Physics, Section B, Proceedings Supplements, Vol. 31, p. 293-300 (1993)