Charged Current Single Pion Production Research Articles

First measurement of the muon neutrino charged current single pion production cross section on water with the T2K near detector

The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ${\sim}0.8$ GeV. The differential measurements are presented as a function of muon and pion kinematics, in the restricted phase-space defined by $p_{\pi^+}>200$MeV/c, $p_{\mu^-}>200$MeV/c, $\cos \theta_{\pi^+}>0.3$ and $\cos \theta_{\mu^-}>0.3$. The total flux integrated $\nu_\mu$ charged current single positive pion production cross section on water in the restricted phase-space is measured to be $\langle\sigma\rangle_\phi=4.25\pm0.48 (\mathrm{stat})\pm1.56 (\mathrm{syst})\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$. The total cross section is consistent with the NEUT prediction ($5.03\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$) and 2$\sigma$ lower than the GENIE prediction ($7.68\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but over-estimates the overall cross section normalization.

Impact of nuclear effects on weak pion production at energies below 1 GeV

Charged-current single pion production in scattering off 12C is investigated for neutrino energies up to 1 GeV. An impact of nuclear effects with in-medium modifications of the Delta(1232) resonance properties as well as an effective field theory nonresonant background contribution are discussed. Dependence of the fraction of Delta(1232) decays into npnh states on incident neutrino energy is estimated. A model of Nieves et al. [1] is further developed by performing exact integration avoiding several approximations. The effect of exact integration is investigated both for double-differential and total neutrino-nucleus cross sections.

Lepton mass effects in weak charged current single pion production

Different approaches to take into account nonzero lepton mass effects in the Rein-Sehgal model are compared. Modification of the axial current due to a pion pole term is included, and it is shown that it leads to large reduction of the antineutrino cross section and a change of the shape of $d\ensuremath{\sigma}/d{Q}^{2}$.