Possible Extensions of the Unified Model for Fundamental Particles

Abstract

Starting from usual quartet model ( 4-quarks and 4-leptons), possible extensions of the model are discussed. In order that two fundamental principles are assumed; one is modi­ fied B-L and the other is E -symmetry, models are required to be closed for these principles. Sixteen possible models and their interactions, including extra leptons, extra quarks and right-handed currents, are presented. Recent experimental progresses in high energy e-1V reactions, e-e reactions and neutrino reactions seem to give many evidences which suggest that the world of elementary particles is much more wide and profound than considered hitherto.!) In order to understand these phenomena various unified models of elementary particles have been proposed and discussed. 2J Among these models the Sakata model,3J succeeding Nagoya model4J and New Nagoya modePJ gave many impacts for the developments of the elementary particle physics. The Nagoya model is constructed from at least two fundamental principles, one is the composite hypothesis for hadrons and the other is the Baryon-Lepton symmetry. The former, the composite hypothesis, is now widely accepted and its effectiveness is well established. The latter, the B-L symmetry, also became more and more widely accepted. Especially, in order to construct unified models which intend to understand above mentioned recent experiments, the B-L symmetry seems to be an important principle. The philosophy of the Nagoya model was extended to the world of leptons by Taketani and Katayama.6J They proposed neutrino-unified model in which charged leptons are assumed to be constructed by e-charge loading to neutrinoes. This correspondence between neutrino and charged lepton much resembles the B-L sym­ metry. So we call this e-symmetry. Similar pairing in the leptonic world is now widely assumed as weak doublet. 7l Thus the importance of the two symmetry principles (or correspondence); B-L symmetry and e-symmetry, seems to become more and more clear for the construction of the unified model. Here in this work we extend the context of these two symmetry principles and discuss various possible unified models including extra leptons, extra quarks