Can String Theory Predict the Weinberg Angle?
arXiv:0706.0217 · doi:10.1103/PhysRevD.76.086006
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).
35 pages, 6 figures
References in corpus (19)
- Extra Spacetime Dimensions and Unification
- Gauge Unification in Higher Dimensions
- Duality Anomaly Cancellation, Minimal String Unification and the Effective Low-Energy Lagrangian of 4-D Strings
- A Mini-Landscape of Exact MSSM Spectra in Heterotic Orbifolds
- Searching for realistic 4d string models with a Pati-Salam symmetry -- Orbifold grand unified theories from heterotic string compactification on a Z6 orbifold
- Supersymmetric Standard Model from the Heterotic String
- Gauge Unification In Six Dimensions
- Constructing 5d orbifold grand unified theories from heterotic strings
- Heterotic Brane World
- Unification in 5D SO(10)
- Gauge Unification in Highly Anisotropic String Compactifications
- Running and Matching from 5 to 4 Dimensions
- String Unification, Higher-Level Gauge Symmetries, and Exotic Hypercharge Normalizations
- Dual Models of Gauge Unification in Various Dimensions
- Spectra in Standard-like Z_3 Orbifold Models
- Algorithmic Algebraic Geometry and Flux Vacua
- Geometry of Rank Reduction
- Geometric scaling in high-energy QCD at nonzero momentum transfer
- The Higgs Mechanism in Heterotic Orbifolds
Cited by in corpus (8)
- The Heterotic Road to the MSSM with R parity
- Heterotic Z6-II MSSM Orbifolds in Blowup
- Towards Low Energy Physics from the Heterotic String
- An Electroweak Monopole, Dirac Quantization and the Weak Mixing Angle
- Grand Unification in the Heterotic Brane World
- Correlation Classes on the Landscape: To What Extent is String Theory Predictive?
- A Simple Introduction to Grobner Basis Methods in String Phenomenology
- Do Incomplete GUT Multiplets Always Spoil Unification?