CP-Violating Neutrino Nonstandard Interactions in Long-Baseline-Accelerator Data

Neutrino oscillations in matter provide a unique probe of new physics. Leveraging the advent of neutrino appearance data from NOvA and T2K in recent years, we investigate the presence of CP-violating neutrino nonstandard interactions in the oscillation data. We first show how to very simply approximate the expected NSI parameters to resolve differences between two long-baseline appearance experiments analytically. Then, by combining recent NOvA and T2K data, we find a tantalizing hint of CP-violating NSI preferring a new complex phase that is close to maximal: phi(e mu) or phi(e tau) approximate to 3 pi/2 with vertical bar epsilon(e mu vertical bar) or vertical bar epsilon(e tau)vertical bar similar to 0.2. We then compare the results from long-baseline data to constraints from IceCube and COHERENT.

Automated summary

Studying neutrino oscillations in matter provides insight into potential CP-violating nonstandard interactions. By analyzing data from NOvA and T2K experiments, researchers have identified hints of CP-violating NSI with a new complex phase close to maximal, based on the estimated NSI parameters combined with experimental results. Comparisons have been made between long-baseline data and constraints from IceCube and COHERENT.