U(1) Froggatt-Nielsen model for quark mass hierarchy in 2HDM

Abstract: One approach to understanding the observed hierarchy in quark masses is by using the Froggatt-Nielssen mechanism. In this model new exotic (and presumable yet undetected) particles are introduced. By forcing the particles of the Standard Model to interact with the postulated particles it is possible to create a mass suppression mechanism which can explain the observed quark mass relations. The mechanism is studied in a 2-Higgs-doublet model without any restricting symmetries other than CP-conservation. A danger with such an approach is flavor changing neutral currents at tree level in the Higgs sector - which yet are unobserved. Whether the mechanism can be used to explain mass ratios, the CKM-matrix for quark mixing and the absence of flavor changing currents is investigated with focus on U(1)-symmetries for the interaction between particles of the Standard Model and the new particles.