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

TL;DR

This paper introduces a novel analysis of neutral-current events at long-baseline experiments to constrain neutrino non-standard interactions, providing improved bounds and complementarity with other data sources.

Contribution

It develops a framework to parametrize NSI effects on cross sections and applies it to NOvA data, offering new constraints on axial-vector and vector NSI parameters.

Findings

Improved constraints on axial-vector NSI parameters from NOvA data.

Disfavoring of large diagonal vector NSI values related to LMA-Dark.

Highlighting the complementarity between charged and neutral current NSI searches.

Abstract

We explore, for the first time, {\textit{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 effect of NSI on the cross section. Then, as an example, we analyze NOvA neutral-current data which provides significantly improved constraints on the axial-vector NSI parameters $\varepsilon_{\mu\mu}^A,~\varepsilon_{\tau\tau}^A$ and $\varepsilon_{e\mu}^A$. This is highly complementary to constraints from SNO data, which, differently from long-baseline neutral current data, is not sensitive to isospin conserving NSIs $\varepsilon^A_u=\varepsilon^A_d$. Additionally, we disfavor large values of the diagonal vectorial NSI $\varepsilon_{\mu\mu}^V$ and \varepsilon_{\tau\tau}^V$ which originate from the LMA-Dark solution. We also highlight the complementarity between NSI searches at oscillation experiments using charged current and neutral current channels.