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arXiv · 2103.07147

Majorana neutrino masses by D-brane instanton effects in magnetized orbifold models

Kouki Hoshiya·Shota Kikuchi·Tatsuo Kobayashi·Kaito Nasu·Hikaru Uchida·Shohei Uemura
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Abstract

We study Majorana neutrino masses induced by D-brane instanton effects in magnetized orbifold models. We classify possible cases, where neutrino masses can be induced. Three and four generations are favored in order to generate neutrino masses by D-brane instantons. Explicit mass matrices have specific features. Their diagonalizing matrices correspond to the bimaximal mixing matrix in the case with even magnetic fluxes, independently of the modulus value $\tau$. On the other hand, for odd magnetic fluxes, diagonalizing matrices correspond nearly to the tri-bimaximal mixing matrix near $\tau =i$, while they become the bimaximal mixing matrix for larger ${\rm Im}\tau$. For even fluxes, neutrino masses are modular forms of the weight 1 on $T^2/\mathbb{Z}_2$, and they have symmetries such as $S_4'$ and ${\Delta'}(96)\times \mathbb{Z}_3$.

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Kouki Hoshiya, Shota Kikuchi, Tatsuo Kobayashi, Kaito Nasu, Hikaru Uchida, Shohei Uemura. 2021-03-12. Majorana neutrino masses by D-brane instanton effects in magnetized orbifold models. https://arxiv.org/abs/2103.07147

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