Comment on "Three Extra Mirror or Sequential Families: Case for a Heavy   Higgs Boson and Inert Doublet"
  In a recent Letter Martinez et al.2011 have argued that the existence of extra three families is still perfectly in accord with the standard model (SM), as long as an additional Higgs doublet is also present. Here we claim that the mentioned accordance can be obtained with less reliance on BSM physics like additional Higgs doublets, but benefiting from Majorana neutrinos is sufficient. 
M. Sahin (TOBB University of Economics and Technology, Ankara,   Turkey), S. Sultansoy (TOBB University of Economics and Tec...
hep-ph hep-ex