Role of unphysical neutrino phases in the phenomenology of consistently defined textures. Case study: traceless neutrino mass matrix

TL;DR

This paper investigates how unphysical neutrino phases influence the phenomenology of neutrino mass matrices, specifically a traceless texture, highlighting their impact on texture definition despite being unobservable.

Contribution

It demonstrates that unphysical phases affect neutrino mass matrix phenomenology through texture redefinition and provides a theoretical realization using A5 flavor symmetry.

Findings

Unphysical phases alter the neutrino mass matrix texture.

Phenomenological effects depend on phase inclusion.

A theoretical model based on A5 symmetry supports the texture.

Abstract

We highlight the role played by the unphysical phases in the definition of neutrino mass matrix, showing it does not relate to mere semantics, rather it has an effect on the phenomenology. As a case study, we take the neutrino mass matrix texture characterized by a vanishing trace, and study the effect of the phases, physical and unphysical, in its definition. We undergo a thorough phenomenological analysis, first (second) when the unphysical (CP) phases are vanishing, then move on to the general case where all phases exist. We stress that the effect of the unphysical phases on the phenomenology originates from changing the texture definition upon introducing them, while they are not observable. Finally we present a theoretical realization of the texture based on $A_5$ non-abelian flavor symmetry, which is also related to a consistently defined texture.