Non-standard neutrino interactions at neutrino experiments and colliders

The impact of new physics on the interactions of neutrinos with other particles can be parametrized by a set of effective four-fermion operators called non-standard neutrino interactions (NSIs). This NSI framework is useful for studying the complementarity between different types of neutrino experiments. In this work, we further compare the reach of neutrino experiments with high-energy collider experiments. Since high-energy colliders often probe the mass scale associated with the four-fermion operators, the effective field theory approach becomes invalid and explicit models must be utilized. We study a variety of representative simplified models including new U(1) gauge bosons, scalar leptoquarks, and heavy neutral leptons. For each of these, we examine the model parameter space constrained by NSI bounds from current and future neutrino experiments, and by data from the Large Hadron Collider and planned electron-positron and muon colliders. We find that in the models we study, with the possible exceptions of muon-philic leptoquarks and heavy neutral leptons mixing with electron or muon neutrinos, collider searches are more constraining than neutrino measurements. Additionally, we briefly comment on other model building possibilities for obtaining models where neutrino experiments are most constraining.