Search for $CP$-Violating Neutrino Nonstandard Interactions with the NOvA Experiment

This Letter reports a search for charge-parity ($CP$) symmetry violating nonstandard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters. Data from ${\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)\to {\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)$ and ${\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)\to {\nu }_{e}\left({\overline{\nu }}_{e}\right)$ oscillation channels are used to measure the effect of the NSI parameters ${ϵ}_{e\mu }$ and ${ϵ}_{e\tau }$. With 90% CL the magnitudes of the NSI couplings are constrained to be $|{ϵ}_{e\mu }|\lesssim 0.3$ and $|{ϵ}_{e\tau }|\lesssim 0.4$. A degeneracy at $|{ϵ}_{e\tau }|\approx 1.8$ is reported, and we observe that the presence of NSI limits sensitivity to the standard $CP$ phase ${\delta }_{CP}$.