Composite leptons at the LHC

In some models of electroweak interactions the W and Z bosons are considered composites, made up of spin-$\frac12$ subconstituents. In these models a spin-0 counterpart of the W and Z boson naturally appears, whose higher mass can be attributed to a particular type of hyperfine spin interaction among the various subconstituents. Recently, it has been argued that the scalar state could be identified with the newly discovered Higgs (H) candidate. Here, we use the known spin splitting between the W/Z and H states to infer, within the framework of a purely phenomenological model, the relative strength of the spin-spin interactions. The results are then applied to the lepton sector, and used to crudely estimate the relevant spin splitting between the two lowest states. Our calculations in many ways parallels what is done in the SU(6) quark model, where most of the spin splittings between the lowest lying baryon and meson states are reasonably well-accounted for a simple color hyperfine interaction, with constituent (color-dressed) quark masses. © 2014 World Scientific Publishing Company