Hadroproduction experiments to constrain accelerator-based neutrino fluxes

The precise knowledge of (anti-)neutrino fluxes is one of the largest limitation in accelerator-based neutrino experiments. The main limitations arise from the poorly known production properties of neutrino parents in hadron-nucleus interactions. Strategies used by neutrino experiment to constrain their fluxes using external hadroproduction data will be described and illustrated with an example of a tight collaboration between T2K and NA61/SHINE experiments. This enabled a reduction of the T2K neutrino flux uncertainty from ∼25% (without external constraints) down to ∼10%. On-going developments to further constrain the T2K (anti-)neutrino flux are discussed and recent results from NA61/SHINE are reviewed. As the next-generation long baseline experiments aim for a neutrino flux uncertainty at a level of a few percent, the future data-taking plans of NA61/SHINE are discussed.