On the neutrino mass ordering and flavor mixing structure

TL;DR

This paper investigates the neutrino mass ordering and flavor mixing, suggesting that the normal ordering aligns better with the observed mixing matrix, and provides a testable prediction relating neutrino masses to mixing parameters.

Contribution

It introduces a novel prediction for the ratio |U_{tau 1}|/|U_{tau 2}| based on neutrino masses, favoring the normal mass ordering in the flavor mixing structure.

Findings

Normal neutrino mass ordering is more consistent with the mixing matrix.

A testable relation between neutrino masses and the mixing matrix is proposed.

Abnormal mass ordering appears less natural in the flavor mixing context.

Abstract

Whether the neutrino mass spectrum is normal (m_1 < m_2 < m_3) or abnormal (m_3 < m_1 < m_2) remains an open question, but we show that the latter possibility looks quite unnatural when it is related to the lepton flavor mixing matrix U in a way similar to the reasonable correlation between the quark mass spectrum and the quark flavor mixing matrix. Taking into account the freedom in choosing the basis of weak interactions, we make a novel prediction for |U_{tau 1}|/|U_{tau 2}| in terms of the three neutrino masses in the large tau mass limit. This result is testable, and it implies that the normal neutrino mass ordering is more likely to coincide with the observed structure of U.