On small Dirac neutrino masses in string theory
Abstract We study how tiny Dirac neutrino masses consistent with experimental constraints can arise in string theory SM-like vacua. We use as a laboratory 4d N $$ \mathcal{N} $$ = 1 type IIA Calabi-Yau orientifold compactifications, and in particular recent results on Yukawa couplings at infinite fi...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-01-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1007/JHEP01(2025)083 |
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| Summary: | Abstract We study how tiny Dirac neutrino masses consistent with experimental constraints can arise in string theory SM-like vacua. We use as a laboratory 4d N $$ \mathcal{N} $$ = 1 type IIA Calabi-Yau orientifold compactifications, and in particular recent results on Yukawa couplings at infinite field-space distance. In this regime we find Dirac neutrino masses of the form m ν ≃ g ν ⟨H⟩, with g ν the gauge coupling of the massive U(1) under which the right-handed neutrinos ν R are charged, and which should be in the range g ν ≃ 10 −14 − 10 −12 to reproduce neutrino data. The neutrino mass suppression occurs because the right-handed neutrino kinetic term behaves as K νν ≃ 1/ g ν 2 $$ {g}_{\nu}^2 $$ . At the same time a tower of ν R -like states appears with characteristic scale m 0 ≃ g ν 2 M P $$ {g}_{\nu}^2{M}_{\textrm{P}} $$ ≃ 0.1 − 500 eV, in agreement with Swampland expectations. Two large hidden dimensions only felt by the ν R sector arise at the same scale, while the string scale is around M s ≃ g ν M P ≃ 10 − 700 TeV. Some phenomenological implications and model building challenges are described. We also describe the difficulties in obtaining appropriate tiny neutrino Yukawas in the cases of a single or more than two large dimensions. Thus the case with two large dimensions seems to be quite unique. |
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| ISSN: | 1029-8479 |