$\delta_{\rm CP}$-free constraints on NSI parameters $\varepsilon_{e\mu}$ and $\varepsilon_{e\tau}$ using high-purity $\nu_\mu\,{\rm CC}$ events at IceCube DeepCore

TL;DR

This study uses IceCube DeepCore atmospheric neutrino data to set constraints on NSI parameters $\,varepsilon_{e\,mu}$ and $\,varepsilon_{e\tau}$, independent of the CP-violating phase, complementing other experimental bounds.

Contribution

First constraints on $\,varepsilon_{e\mu}$ and $\,varepsilon_{e\tau}$ from IceCube data that are free from $\,delta_{CP}$-degeneracy, using high-purity $ u_\,mu$ CC events.

Findings

Data agrees with standard neutrino interactions.

Bounds on NSI parameters are consistent with existing constraints.

Constraints are complementary to long-baseline experiments.

Abstract

Atmospheric neutrinos provide a unique avenue to probe theories beyond the Standard Model (BSM) over a wide range of energies and path lengths. The theory of non-standard interactions (NSI) of neutrinos is one of the important BSM scenarios, which can modify flavor oscillations of atmospheric neutrinos traveling through the Earth. In this work, we use a high-purity $\nu_{\mu}$ charged-current (CC) sample of atmospheric neutrinos from IceCube DeepCore with a livetime of 7.5 years to search for the NSI parameters $\varepsilon_{e\mu}$, $\varepsilon_{e\tau}$, and $\varepsilon_{ee}-\varepsilon_{\mu\mu}$. The $\nu_{\mu}$ CC events mainly come from the $\nu_{\mu}$ survival channel having no significant dependence on $\delta_{\rm CP}$. Therefore, the constraints on $\varepsilon_{e\mu}$ and $\varepsilon_{e\tau}$ obtained using this $\nu_{\mu}$ CC sample are expected to be free from the $\delta_{\rm CP}$-degeneracy. The data sample is found to be in agreement with the standard neutrino interactions. Therefore, we place bounds on these NSI parameters that are consistent with and comparable to existing experimental constraints. These $\delta_{\rm CP}$-free constraints from IceCube DeepCore are complementary to those from the long-baseline neutrino oscillation experiments, where the appearance channel depends on $\delta_{\rm CP}$.