Possible existence of extra SM families and/or isosinglet E_6 quarks may sufficiently decrease |V_tb| of CKM matrix so that toponia can be formed. Production of pseudoscalar toponium at the LHC and VLHC has been considered. The observability of eta_t->gamma+gamma signal is discussed.
@article{arxiv.hep-ph/0312216,
title = {On the observability of pseudoscalar toponium at future hadron colliders},
author = {O. Cakir and R. Ciftci and E. Recepoglu and S. Sultansoy},
journal= {arXiv preprint arXiv:hep-ph/0312216},
year = {2014}
}