Improvements on perturbative oscillation formulas including non-standard neutrino Interactions

TL;DR

This paper develops perturbative formulas for neutrino oscillation probabilities incorporating non-standard interactions, clarifying parameter degeneracies and aiding interpretation of long-baseline experiment results.

Contribution

It introduces a compact perturbative framework that links non-standard interaction parameters with standard oscillation parameters, revealing degeneracies and their impact on experimental analyses.

Findings

Perturbative formulas include NSI effects with similar structure to standard oscillations.

Degeneracies between standard and non-standard parameters are identified.

Long-baseline experiment degeneracies are explained by parameter marginalization.

Abstract

We present perturbative oscillation probabilities for electron and muon channels including non-standard interaction (NSI) effects. The perturbation was performed in standard parameters $\Delta m^2_{21}/\Delta m^2_{31}$ and $\sin^2{(\theta_{13})}$ as in non-standard interaction couplings. Our goal is to match non-standard parameters with the standard ones. This leads to oscillation probabilities with NSI compact and with functional structure similar to the Standard Oscillation (SO) case. Such formalism allows us to recognize degeneracies between standard oscillation parameters and NSI parameters. In such scenario, we also have an educated guess about the origin of the reported behavior of long-baseline experiments degeneracies, which should be due to marginalization on standard oscillation parameters $\delta_{\rm CP}$, $\theta_{23}$ and NSI parameters.