2008/03/31 by Mirjam Cvetič, Mirjam Cvetic, Paul Langacker · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Noncommutative and Quantum Gravity Theories #Particle physics theoretical and experimental studies #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.78.066012
published as Phys.Rev.D78:066012,2008 · 4 pages, 1 figure minor corrections, the version to be published in Phys. Rev. D
arxiv created 2008/09/16 · openalex publication_date 2008/09/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We present a stringy mechanism to generate Dirac neutrino masses by D-instantons in an experimentally relevant mass scale without fine-tuning. Within type IIA string theory with intersecting D6-branes, we spell out specific conditions for the emergence of such couplings and provide a class of supersymmetric local SU(5) grand unified models, based on the Z2\ifmmode×\else\texttimes\fiZ2^\ensuremath' orientifold compactification, where perturbatively absent Dirac neutrino masses can be generated by D2-brane instantons in the experimentally observed mass regime, while Majorana masses remain absent, thus providing an intriguing mechanism for the origin of small neutrino masses due to nonperturbative stringy effects.