A Search for the Fourth SM Family: Tevatron still has a Chance

Abstract

Existence of the fourth family follows from the basics of the Standard Model and the actual mass spectrum of the third family fermions. We discuss possible manifestations of the fourth SM family at existing and future colliders. The LHC and Tevatron potentials to discover the fourth SM family have been compared. The scenario with dominance of the anomalous decay modes of the fourth family quarks has been considered in details.

Status of the Fourth Generation - A Brief Summary of B3SM-III Workshop in Four Parts

“…For example, a new phenomenological model involving strongly coupled fourth generation quarks has been proposed in [42] to address top-pair forward-backward asymmetry observed at the Tevatron experiments [43]. It is interesting to note that the experimental signatures of the fourth generation in new models can be quite unusual and might require significant rethinking of conventional searches at the LHC [24,44].…”

“…Further constraints (which apply not only to fourth generation) have recently been extracted on the grounds that lepton number violation due to the interactions involving new Majorana neutrinos can wash out considerably any GUT scale generated or otherwise preexisting baryon asymmetry of the universe[20] 7. Almost degenerate fourth family quarks and charged lepton are predicted by the Flavor Democracy Hypothesis (see[24] and references therein. )8 These large values seem to contradict those found in[27], probably because of not yet considering Z → b b constraint 9.…”

New IceCube data and color octet neutrino interpretation of the PeV energy events

“…There are two strong arguments favoring preon models: inflation of "fundamental" particles and free parameters in the SM (other BSM models, including SUSY, drastically increase the number of free parameters) and mixing of "fundamental" quarks and leptons. The first one, namely "inflation", historically results in discovery of new level of matter two times during the last century: periodical table of chemical elements was clarified by Rutherford experiment, inflation of hadrons results in quark model (see Table 1 from [11]).…”