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T: Teilchenphysik

T XII: HV XII

T XII.1: Hauptvortrag

Donnerstag, 13. März 2003, 09:15–10:00, FO1

Extra Dimensions and Grand Unification — •Arthur Hebecker — DESY

The most successful scenarios for physics beyond the Standard Model rely on supersymmetry and conjecture the unification of the known gauge interactions in a simple group at a high energy scale. One of the more problematic aspects of such models is the mechanism breaking the gauge symmetry of this Grand Unified Theory to that of the Standard Model. It has recently been shown that extra dimensions allow for a very simple and successful realization of the required symmetry breaking, which is based on field-theoretic orbifolds. In my talk, I will discuss the general structure of these new models of Grand Unification, focussing in particular on implications for proton decay, the fermion mass spectrum, and leptogenesis. If, in addition to the orbifold breaking, the unified gauge symmetry is also broken by the vacuum expectation value of a bulk field, power-like loop corrections to gauge coupling unification can arise. I will discuss the calculability and possible phenomenological implications of these power-like threshold corrections and show that, in some of the simplest and most attractive settings, they can be quantitatively analyzed within the framework of effective field theory.