NEUTRAL CURRENT COUPLING-CONSTANTS FROM NEUTRINO-ELECTRON AND ANTINEUTRINO-ELECTRON SCATTERING

We are reporting on a determination of neutral current coupling constants from a study of differential cross sections of muon- (anti)neutrino-electron scattering. The results were obtained with the CHARM-II detector which was exposed to the CERN wide band neutrino beam in the years 1987-1990. A total of about 2100 ve and 2200 v¯e scattering events were observed. From a comparison between the data and predicted event distributions, the effective vector and axial-vector neutral current coupling constants of the electron were determined to be ge_v=-0.025+/-0.019 and ge_A=-0.503+/-0.018

FLAVOR UNIVERSALITY OF NEUTRINO COUPLINGS WITH THE Z

We are reporting the first experimental result of the coupling of the muon neutrino with the Z. This result is in good agreement with the average value of the coupling of the three neutrino families as derived from the invisible decay width of the Z. We also determined g(v tau) assuming N-v = 3

SEARCH FOR MUON TO ELECTRON NEUTRINO OSCILLATIONS

A search for upsilon(mu) --> upsilon(e) and ($) over bar upsilon(mu) --> ($) over bar upsilon(e) oscillations has been carried out with the CHARM LI detector exposed to the CERN wide band neutrino beam. The data were collected over five years, alternating beams mainly composed of muon-neutrinos and muon-antineutrinos. The number of interactions of upsilon(e) and ($) over bar upsilon(e) observed is comparable with the number of events expected from flux calculations. For large squared mass differences the upper limits obtained on the mixing angle are sin(2)2 theta < 9.4.10(-3) for upsilon(mu) oscillating to upsilon(e) and sin(2)2 theta < 4.8.10(-3) for ($) over bar upsilon(mu) to ($) over bar upsilon(e) at the 90% confidence level. Combining neutrino and antineutrino data the upper limit is 5.6.10(-3)

CONSTRAINTS ON ADDITIONAL Z-BOSONS DERIVED FROM NEUTRINO-ELECTRON SCATTERING MEASUREMENTS

We report new constraints on the existence of additional Z bosons derived from neutrino-electron scattering data. The analysis is based on data taken by the CHARM II Collaboration during five years of exposure of the detector to the wide band neutrino beam at CERN. The limits on the mass of these new particles are evaluated in the framework of E6 superstring-inspired theories and Left-Right symmetric models. Limits on the so-called Z1 are also reported