Constraining non-standard neutrino interactions with neutral current events at long-baseline oscillation experiments

Abstract: We explore, for the first time, neutral-current events at long-baseline experiments to constrain vector and axial-vector neutrino non-standard interactions (NSI) with quarks. We leverage the flavor dependence of NSIs to perform an oscillation analysis in the neutral-current channel.
We first introduce a framework to parametrize the impact of NSIs on the neutrino–nucleus cross section. As an illustrative example, we analyze NOvA neutral-current data, which provide significantly improved constraints on the axial-vector NSI parameters εμμA, εττA, and εeμA.varepsilon_{mumu}^A, varepsilon_{tautau}^A, text{and} varepsilon_{emu}^A.εμμA​, εττA​, and εeμA​.
These constraints are highly complementary to those obtained from SNO.
In addition, we disfavour large values of the diagonal vector NSI parameters εμμVvarepsilon_{mumu}^VεμμV​ and εττVvarepsilon_{tautau}^VεττV​, which arise in the LMA-Dark solution. Finally, we highlight the complementarity between NSI searches at oscillation experiments using charged-current and neutral-current channels.