2005/02/02 by Joel Giedt, Gordon Kane, G. L. Kane +3 · 5 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Neutrino Physics Research #Particle physics theoretical and experimental studies #hep-ex #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.71.115013
published as Phys.Rev. D71 (2005) 115013 · 18 pages in RevTeX format. Single-column postscript version available at http://sage.hep.upenn.edu/~bnelson/singpre.ps
arxiv created 2005/02/02 · openalex publication_date 2005/06/28 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
String theories in principle address the origin and values of the quark and lepton masses. Perhaps the small values of neutrino masses could be explained generically in string theory even if it is more difficult to calculate individual values, or perhaps some string constructions could be favored by generating small neutrino masses. We examine this issue in the context of the well-known three-family standard-like Z3 heterotic orbifolds, where the theory is well enough known to construct the corresponding operators allowed by string selection rules, and analyze the D- and F-flatness conditions. Surprisingly, we find that a simple seesaw mechanism does not arise. It is not clear whether this is a property of this construction, or of orbifolds more generally, or of string theory itself. Extended seesaw mechanisms may be allowed; more analysis will be needed to settle that issue. We briefly speculate on their form if allowed and on the possibility of alternatives, such as small Dirac masses and triplet seesaws. The smallness of neutrino masses may be a powerful probe of string constructions in general. We also find further evidence that there are only 20 inequivalent models in this class, which affects the counting of string vacua.