We elaborate that general intersecting brane models on orbifolds are obtained from type I string compactifications and their T-duals. Symmetry breaking and restoration occur via recombination and parallel separation of branes, preserving supersymmetry. The Ramond-Ramond tadpole cancellation and the toron quantization constrain the spectrum as a branching of the adjoints of SO(32), up to orbifold projections. Since the recombination changes the gauge coupling, the single gauge coupling of type I could give rise to different coupling below the unification scale. This is due to the nonlocal properties of the Dirac-Born-Infeld action. The desirable weak mixing angle sin2 θw = 3/8 is naturally explained by embedding the quantum numbers to those of SO(10).
|Number of pages||32|
|Journal||International Journal of Modern Physics A|
|State||Published - 30 Jul 2007|
- Intersecting branes
- Weak mixing angle