Corrections to Tribimaximal Mixing from Nondegenerate Phases

TL;DR

This paper investigates how small phase differences in the right-handed neutrino mass matrix can cause deviations from the tribimaximal lepton mixing pattern, providing analytical expressions and favoring a normal hierarchy spectrum.

Contribution

It introduces a seesaw scenario linking phase splitting to mixing corrections, with analytical formulas and implications for CP phases and neutrino hierarchy.

Findings

Solar mixing angle slightly smaller than 35.3°

Dirac CP phase nearly maximal

Normal hierarchy neutrino spectrum favored

Abstract

We propose a seesaw scenario that possible corrections to the tribimaximal pattern of lepton mixing are due to the small phase splitting of the right-handed neutrino mass matrix. we show that the small deviations can be expressed analytically in terms of two splitting parameters($\delta_1$ and $\delta_2$) in the leading order. The solar mixing angle $\theta_{12}$ favors a relatively smaller value compared to zero order value ($35.3^\circ$), and the Dirac type CP phase $\delta$ chooses a nearly maximal one. The two Majorana type CP phases $\rho$ and $\sigma$ turn out to be a nearly linear dependence. Also a normal hierarchy neutrino mass spectrum is favored due to the stability of perturbation calculations.