Testing matter effects in propagation of atmospheric and long-baseline neutrinos

TL;DR

This paper analyzes how matter effects influence atmospheric and long-baseline neutrino oscillations, generalizing the standard matter potential to include non-standard interactions, and assesses the constraints and implications of these effects on neutrino data.

Contribution

It introduces a generalized parametrization of matter effects in neutrino oscillations, exploring the constraints from data and their impact on neutrino mass and mixing determinations.

Findings

The strength of matter potential cannot be fully determined from current data.

The flavor composition of matter effects is tightly constrained.

In certain scenarios, matter effects can reduce tensions between neutrino and antineutrino data.

Abstract

We quantify our current knowledge of the size and flavor structure of the matter effects in the evolution of atmospheric and long-baseline neutrinos based solely on the analysis of the corresponding neutrino data. To this aim we generalize the matter potential of the Standard Model by rescaling its strength, rotating it away from the e-e sector, and rephasing it with respect to the vacuum term. This phenomenological parametrization can be easily translated in terms of non-standard neutrino interactions in matter. We show that in the most general case, the strength of the potential cannot be determined solely by atmospheric and long-baseline data. However its flavor composition is very much constrained and the present determination of the neutrino masses and mixing is robust under its presence. We also present an update of the constraints arising from this analysis in the particular case in which no potential is present in the e-mu and e-tau sectors. Finally we quantify to what degree in this scenario it is possible to alleviate the tension between the oscillation results for neutrinos and antineutrinos in the MINOS experiment and show the relevance of the high energy part of the spectrum measured at MINOS.