A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment

Abstract

We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions (ν _μ n→μ ⁻ p and $\bar{\nu }_{\mu}p\to\mu^{+}n$ ) 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 ( $\bar{\nu}_{\mu}$ ) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3–100 GeV are $\langle \sigma_{\mathrm{qel}}\rangle_{\nu_{\mu}}=(0.92\pm0.02(\mathrm{stat})\pm0.06(\mathrm{syst}))\times10^{-38}~\mathrm{cm}^{2}$ and $\langle\sigma_{\mathrm{qel}}\rangle_{\bar{\nu}_{\mu}}=(0.81\pm0.05(\mathrm{stat})\pm0.09(\mathrm{syst}))\times10^{-38}~\mathrm{cm}^{2}$ 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 quasi-elastic 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.