Neutrino magnetic moments: effective versus fundamental parameters

TL;DR

This paper clarifies the correct interpretation of neutrino magnetic moments, emphasizing that effective parameters vary across experiments and should not be considered universally comparable, impacting global analyses.

Contribution

It provides a clear definition of effective neutrino magnetic moments for different experimental setups and highlights the importance of context in their interpretation.

Findings

Effective magnetic moments depend on experiment-specific factors.

Misinterpretation can lead to incorrect conclusions in neutrino physics.

Clarification aids in accurate global analysis of neutrino magnetic moments.

Abstract

The search for neutrino magnetic moments offers a valuable window into physics beyond the Standard Model. However, a common misconception arises in the interpretation of experimental results: the assumption that the so-called effective neutrino magnetic moment is a universal, experiment-independent quantity. In reality, this effective parameter depends on the specific characteristics of each experiment, including the neutrino source, flavor composition or energy spectrum. As a result, the effective magnetic moment derived from solar neutrino data differs fundamentally from that obtained in reactor or accelerator-based experiments. Treating these quantities as directly comparable can lead to misleading conclusions. In this work, we clarify the proper definition of the effective neutrino magnetic moment in various experimental contexts and discuss the implications of this misconception for global analyses and theoretical interpretations.