Heterotic string models with reduced spectrum and supersymmetry breaking
Lundi 31/03/2008, 16:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
Often heterotic orbifolds contain a large number of states. In search for minimal models we seek inspiration from free fermionic models, which are Z2 x Z2 orbifolds at a special point in the moduli space. The free fermionic formalism allows to deal with asymmetric boundary conditions and I will present a mechanism for reducing the Higgs spectrum of Z2 x Z2 orbifolds to the minimal content, using asymmetric boundary conditions. An additional effect of these boundary conditions is the dramatic reduction of the supersymmetric moduli space and I will present a model which does not seem to accept any supersymmetric solution, signaling a perturbative supersymmetry breaking. I will also discuss a mechanism that allows to obtain Higgs states only from the untwisted sector and matter states only from the twisted sectors in orbifold constructions, hence providing an elegant model building set-up.