Non-Commutative Extensions of the Standard Model
Four different extensions of the Standard Model to non-commutative space-time are considered. They all have the structure group U_Y(1) x SU_L(2) x SU_c(3) but differ through the way Yukawa interaction is implemented. Models based on non-commutative tensor products involve, in general several inequivalent Seiberg-Witten maps of some (Higgs or fermionic) matter field. The non-minimal Non-Commutative Standard Model, advocated by the Munich Group is reproduced at lowest order in the non-commutativity parameter by a particular model of this class. On the other hand, models based on hybrid Seiberg-Witten maps predict electromagnetic couplings of neutral particles like Z-boson, Higgs meson, or neutrino. The non-commutative contributions of the above Standard Model extensions at low energies are evaluated by integrating out all massive bosonic degrees of freedom.