Pion production in neutrino-nucleus interactions

Understanding the process of one-pion production, one of the most prominent reactions at few-GeV energies, is essential for a proper analysis of oscillation experiments. In addition, important questions with regard to the axial sector of hadronic and nuclear physics ask for further investigations. We have developed a formalism to study Δ-mediated one-pion production in neutrino-nucleus interactions. We assess ambiguities stemming from the Δ couplings and quantify the uncertainties in the axial form factors by comparing model predictions with bubble-chamber data. Nuclear effects are described in terms of the relativistic plane-wave impulse approximation using realistic bound-state wave functions. Medium modifications to the Δ mass and width are taken into account. We present various distributions, against Q2, W and outgoing-lepton variables. Recently, the process of coherent pion production from nuclei has attracted a lot of interest. We find that nuclear effects are large. We add two new features to the existing models. First, we go beyond the so-called local approximation, and take into account the full nuclear dynamics of the process. Second, the attenuation of the pion by the medium is computed by means of Glauber transparencies. We present pion distributions for a variety of target nuclei and neutrino energies.