Majorana neutrino mass structure induced by rigid instatons on toroidal orbifold

TL;DR

This paper investigates how rigid D-brane instantons on a toroidal orbifold can generate Majorana neutrino masses and Higgs mu-terms, potentially explaining observed neutrino mixing angles.

Contribution

It provides explicit calculations of Majorana mass matrices and mu-terms induced by rigid instantons on a Z2*Z2' toroidal orbifold, offering new mechanisms for neutrino mass generation.

Findings

Majorana mass matrices with bimaximal mixing are realizable.

Rigid instantons can generate realistic neutrino mixing angles.

Computed mu-term matrices among multiple Higgs pairs.

Abstract

We study effects of D-brane instantons wrapping rigid cycles on Z2*Z2' toroidal orbifold. We compute Majorana masses induced by rigid D-brane instantons and realize bimaximal mixing matrices in certain models. We can also derive more generic mass matrices in other models. The bimaximal mixing Majorana mass matrix has a possibility to explain observed mixing angles. We also compute the mu-term matrix among more than one pairs of Higgs fields induced by rigid D-brane instantons.