Advances in High Energy Physics / 2013 / Article / Fig 2

Review Article

Constraints on a Fourth Generation of Fermions from Higgs Boson Searches

Figure 2

Allowed mass splitting of fourth generation fermions according to the constraints from electroweak precision observables. One clearly sees that mass degenerate quarks of the fourth family are not ruled out. Note, that for this result CKM mixing was neglected. Figure from [15].