Can String Theory Predict the Weinberg Angle?
High Energy Physics - Theory
2008-11-26 v1 High Energy Physics - Phenomenology
Abstract
We investigate whether the hypercharge assignments in the Standard Model can be interpreted as a hint at Grand Unification in the context of heterotic string theory. To this end, we introduce a general method to calculate U(1)_Y for any heterotic orbifold and compare our findings to the cases where hypercharge arises from a GUT. Surprisingly, in the overwhelming majority of 3-2 Standard Models, a non-anomalous hypercharge direction can be defined, for which the spectrum is vector-like. For these models, we calculate sin^2 theta to see how well it agrees with the standard GUT value. We find that 12% have sin^2 theta = 3/8, while all others have values which are less. Finally, 89% of the models with sin^2 theta = 3/8 have U(1)_Y in SU(5).
Cite
@article{arxiv.0706.0217,
title = {Can String Theory Predict the Weinberg Angle?},
author = {S. Raby and A. Wingerter},
journal= {arXiv preprint arXiv:0706.0217},
year = {2008}
}