We have measured the cross section for inverse muon decay in the CERN neutrino wide band beam. From 4808 events observed in the CHARM II detector we derived for the Born term of the asymptotic cross section slope the result (18.16±1.36) × 10 −42 cm 2 GeV −1 . This cross section is in good agreement with the standard model prediction and allows to constrain the scalar coupling of the electron and muon to their neutrinos to | g LL S | 2 <0.405 at 90% CL.
Corrected asymptotic cross section slope. Error is quadratically combined statistical and systematic.
We report on the first observation of neutrino induced production of muon pairs in the electromagnetic field of a nucleus. The data has been obtained using the CHARM II detector exposed to the CERN wideband neutrino and antineutrino beams. A clear signal of 55 ± 16 events is seen in a sample of dimuons of opposite charge without visible recoil at the vertex. The cross section is determined and found to be in agreement with the standard model prediction.
No description provided.
We are reporting an improved determination of the electroweak mixing angle sin 2 Θ w from the ratio of ν μ e to ν μ e scattering cross sections. The CHARM II detector was exposed to neutrino and antineutrino wide band beams at the 450 GeV CERN SPS. Including new data collected in 1989 we have obtained 1316 ± 56 ν μ e and 1453 ± 62 ν μ e events. From the ratio of the visible cross sections we determined sin 2 Θ 0 =0.239 ± 0.009(stat) ± 0.007(syst) without radiative corrections and g V e g A e =0.047 ± 0.046 . Combining this last result with recent results on g A e at LEP we obtain g V e = −0.023 ± 0.023.
Systematic error presented includes error from flux normalization 'F'=1.030+- 0.022, no detaled description of the other sources and of the combination pr ocedure.. 'F'.
Without radiative corrections, systematic error combined in quadrature fromconponents listed under SYSTEMATICS.
With radiative corrections as defined by Marciano-Sirlin scheme, see Phys.Rev.D22(1980)2695, Phys.Rev.Lett.46(1981)163, Phys.Rev.D29(1984)945, Phys.Rev.D31(1985)213E, Nucl.Phys.B217(1983)84. CENTRAL VALUE IS FOR M(TOP)=100 GEV, M(HIGGS)=100 GEV.
We report on a measurement of coherent single charged pion production in neutrino-nucleus scattering. The analysis is based on data taken with the CHARM II detector in beams of muon-neutrinos and -antineutrinos. The event numbers amount to N ( μ − π ) = 748 and N ( μ + π ) = 631. Cross sections and their dependence on the neutrino energy are determined. The results are in agreement with the predictions of models based on the PCAC hypothesis.
Visible cross section for production of pions with energy > 5 GeV.
Visible cross section for production of pions with energy > 5 GeV.
Total cross section from data corrected using the Rein-Sehgal model.
We report our final results from the analysis of the full high statistics sample of events of the reaction ν μ + e − → μ − + ν c collected with the CHARM II detector in the CERN wide-band neutrino beam during the years 1988 to 1991. From a signal of 15758 ± 324 inverse muon decay events we derived, inthe Born approximation, a value of (16.51 ± 0.93) × 10 −42 cm 2 GeV −1 for the asymptotic cross section slope σ E ν , in goodagreement with the Standard Model prediction of 17.23 × 10 −42 cm 2 GeV −1 . The result constrains the scalar coupling of the electron and the muon to | g LL S | 2 < 0.475 at 90% CL.
23.8 is mean neutrino beam energy.
Born approximation of the asymptotic cross section slope obtained by applying radiative corrections, which amount to a 3% effect.. Error is combined statistics and systematics.. 23.8 is mean neutrino beam energy.