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

Peter B Denton,Rebekah Pestes,Julia Gehrlein

doi:10.1103/physrevlett.126.051801

Peter B Denton, Rebekah Pestes + Show 1 more

Open Access

https://doi.org/10.1103/physrevlett.126.051801

Copy DOI

Abstract

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: ϕ_{eμ} or ϕ_{eτ}≈3π/2 with |ε_{eμ}| or |ε_{eτ}|∼0.2. We then compare the results from long-baseline data to constraints from IceCube and COHERENT.

Highlights

Introduction.—Neutrino oscillations have provided the only particle physics evidence for new physics beyond the standard model (BSM) to date [1,2], making it an excellent place to probe new physics scenarios
The environment may modify the phases due to an interaction. Such an interaction exists in the standard model (SM) and is called the Wolfenstein matter effect [3], wherein a neutrino in the electron state of the flavor basis experiences a potential with the background electrons via a charged-current (CC) interaction
In the same paper that pointed out the SM matter effect, Wolfenstein suggested the possibility of a new interaction that provides a matter effect, so-called neutrino nonstandard interactions (NSI) [3,4,5]

Summary

Introduction

Introduction.—Neutrino oscillations have provided the only particle physics evidence for new physics beyond the standard model (BSM) to date [1,2], making it an excellent place to probe new physics scenarios. By diagonalizing U†M2U þ N, one finds the vacuum parameters that a long-baseline accelerator experiment would extract in the presence of NSI at a given energy.

Results

Conclusion