SU(5)xSU(5)' unification and D2 parity: Model for composite leptons
  We study a grand unified SU(5)xSU(5)' model supplemented by D2 parity. The D2 greatly reduces the number of parameters and is important for phenomenology. The model, we present, has various novel and interesting properties.   Because of the specific pattern of grand unification symmetry breaking and emerged strong dynamics at low energies, the Standard Model leptons, along with right-handed/sterile neutrinos, come out as composite states. The generation of the charged fermion and neutrino masses are studied within the considered scenario. Moreover, the issues of gauge coupling unification and nucleon stability are investigated in details. Various phenomenological implications are also discussed. 
Zurab Tavartkiladze
hep-ph