  Background: Pion production gives information on the axial form factors of
nucleon resonances. It also introduces a noticeable background to quasi-elastic
measurements on nuclear targets and thus has a significant impact on precision
studies of neutrino oscillation parameters. Purpose: To clarify
neutrino-induced pion production on nucleons and nuclei. Method: The Giessen
Boltzmann--Uehling--Uhlenbeck (GiBUU) model is used for the description of
neutrino-nucleus reactions. Results: Theoretical results for differential cross
sections for the T2K neutrino flux at the ND280 detector and integrated cross
sections as a function of neutrino energy are given. Two sets of pion
production data on elementary targets are used as inputs to obtain limits for
pion production in neutrino-nucleus reactions. Conclusions: Pion production in
the T2K ND280 detector can help to narrow down the uncertainties in the
elementary pion production cross sections. It can also give valuable
information on the nucleon-Delta axial form factor.
