Experimental Signatures of Strings and Branes

Abstract

Type I string theory provides a D-brane world description of our universe and leads to two new scenaria for physics beyond the Standard Model: low string scale and split supersymmetry. Lowering the string scale in the TeV region provides a theoretical framework for solving the mass hierarchy problem and unifying all interactions. The apparent weakness of gravity can then be accounted by the existence of large internal dimensions, in the submillimeter region, and transverse to a braneworld where we must be confined. I review the main properties of this scenario and its implications for observations at both particle colliders, and in non-accelerator gravity experiments. I also present a concrete realization of split supersymmetry which guarantees gauge coupling unification at the conventional scale MGUT ≃ 2 × 1016GeV.