ACTA PHYSICA POLONICA B, vol.35, no.8, pp.2103-2107, 2004 (SCI-Expanded)
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) --> gammagamma signal is discussed.