Instanton induced charged fermion and neutrino masses in a minimal Standard Model scenario from intersecting D-branes

TL;DR

This paper explores how string instanton effects in a minimal D-brane Standard Model can generate fermion and neutrino masses that are perturbatively forbidden, providing a non-perturbative origin for these masses and textures.

Contribution

It demonstrates that string instantons induce Yukawa couplings for fermions and neutrinos in a minimal D-brane Standard Model, explaining mass generation beyond perturbation theory.

Findings

Instanton effects generate fermion mass terms absent at perturbative level.

Heavy Majorana neutrino masses are produced via non-perturbative effects.

A neutrino mass texture consistent with experimental data is constructed.

Abstract

String instanton Yukawa corrections from Euclidean D-branes are investigated in an effective Standard Model theory obtained from the minimal U(3)xU(2)xU(1) D-brane configuration. In the case of the minimal chiral and Higgs spectrum, it is found that superpotential contributions are induced by string instantons for the perturbatively forbidden entries of the up and down quark mass matrices. Analogous non-perturbative effects generate heavy Majorana neutrino masses and a Dirac neutrino texture with factorizable Yukawa couplings. For this latter case, a specific example is worked out where it is shown how this texture can reconcile the neutrino data.