We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions (ν μ n → μ − p andν μ p → μ + n) using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total ν μ (ν μ ) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3-100 GeV are σ qel ν μ = (0.92 ± 0.02(stat) ± 0.06(syst)) × 10 −38 cm 2 and σ qel ν μ = (0.81 ± 0.05(stat) ± 0.09(syst)) × 10 −38 cm 2 for neutrino and antineutrino, respectively. The axial mass parameter M A was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is M A = 1.05±0.02(stat)±0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross section and extracted from the pure Q 2 shape analysis of the high purity sample of ν μ quasielastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured M A is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of M A is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on M A , these results are compatible with the more precise NOMAD value.PACS 13.15.+g · 25.30.Pt

We present a Study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44 x 10(6) muon-neutrino Charged Current interactions in the energy range 2.5 <= E(nu) <= 300 GeV. Neutrino events with only one visible pi(0) in the final state are expected to result from two Neutral Current processes: coherent pi(0) production, nu + A -> nu + A + pi(0) and single pi(0) production in neutrino-nucleon scattering. The signature of coherent pi(0) production is an emergent pi(0) almost collinear with the incident neutrino while pi(0)'s produced in neutrino-nucleon deep inelastic scattering have larger transverse momenta. In this analysis all relevant backgrounds to the coherent pi(0) production signal are measured using data themselves. Having determined the backgrounds, and using the Rein-Sehgal model for the coherent pi(0) production to compute the detection efficiency, we obtain 4630 +/- 522(stat) +/- 426(syst) corrected coherent-pi(0) events with E(pi 0) >= 0.5 GeV. We measure sigma(nu A -> nu A pi(0)) = 172.6 +/- 8.1 (stat) +/- 6.9(syst)] x 10(-40) cm(2)/nucleus. This is the most precise measurement of the coherent pi(0) production to date. (C) 2009 Elsevier B.V. All rights reserved