Disentangling the Seesaw in the Left-Right Model -- An Algorithm for the General Case

TL;DR

This paper develops a robust numerical algorithm to determine the neutrino Dirac mass matrix in the left-right model when the generalized parity symmetry is broken, extending previous analytical solutions to more general cases.

Contribution

The authors introduce a stable, prescriptive numerical method for extracting the neutrino Dirac mass matrix in the broken parity scenario, overcoming limitations of earlier analytical approaches.

Findings

The algorithm is stable and effective in most cases.

It can handle data consistent with current neutrino experiments.

Provides insights into neutrino mass and mixing structures.

Abstract

Senjanovic and Tello have analyzed how one could determine the neutrino Dirac mass matrix in the minimal left-right model, assuming that the mass matrices for the light and heavy neutrinos could be taken as inputs. They have provided an analytical solution for the Dirac mass matrix in the case that the left-right symmetry is implemented via a generalized parity symmetry and that this symmetry remains unbroken in the Dirac Yukawa sector. We extend the work of Senjanovic and Tello to the case in which the generalized parity symmetry is broken in the Dirac Yukawa sector. In this case the elegant method outlined by Senjanovic and Tello breaks down and we need to adopt a numerical approach. Several iterative approaches are described; these are found to work in some cases but to be highly unstable in others. A stable, prescriptive numerical algorithm is described that works in all but a vanishingly small number of cases. We apply this algorithm to numerical data sets that are consistent with current experimental constraints on neutrino masses and mixings. We also provide some additional context and supporting explanations for the case in which the parity symmetry is unbroken.