Intersecting Brane World from Type I Compactification

TL;DR

This paper explores how intersecting brane models in string theory can be derived from type I compactifications, analyzing symmetry breaking, spectrum constraints, and implications for gauge couplings and the weak mixing angle.

Contribution

It demonstrates the derivation of intersecting brane models from type I string compactifications and their T-duals, including spectrum constraints and gauge coupling implications.

Findings

Recombination preserves supersymmetry.

Spectrum constrained by tadpole cancellation and orbifold projections.

Natural explanation for sin^2 theta_W = 3/8 within SO(10) embedding.

Abstract

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 cancelation 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 weak mixing angle sin^2 theta_W = 3/8 is naturally explained by embedding the quantum numbers to those of SO(10).