NEUTRAL CURRENT COUPLING-CONSTANTS FROM NEUTRINO-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 to 1991. A total of about 3000 ve and 3000 ve scattering events were observed. We present a preliminary value of sin2φw determined with the ratio of neutrino and antineutrino electron scattering cross-sections, based on the full data sample, and we give a determination of the effective vector and axial-vector neutral current coupling constants and the first measurement of the shape of the y-distributions based on 80% of the total statistics

Neutral-current Coupling-constants From Nu-mu-e- and (nu)bar-mu-e- Scattering

We report on determinations of the neutral current coupling constants of the electron from the study of muon neutrino and antineutrino scattering off electrons. The results were obtained with the CHARM II detector which was exposed to the CERN wide band neutrino beam during the years 1987 to 1991. We present the determination of g V and g A from the measurement of νμ e and ν̄μ e cross sections with 80% of the data and a preliminary result for sin2θ w from the ratio of νμ e and v̄μ e cross sections, using the full data sample. We furthermore give results from the comparison of neutrino electron scattering with inverse muon decay and present the first measurement of the y‐distributions for νμ e and ν̄μ e scattering. The agreement between our results and those from the measurements at LEP demonstrates the validity of the Standard Model over a range in momentum transfer which spans six orders of magnitude

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)