Figure 2: Reproduction of the fit of the oblique parameters and as given from Figure 2 in [11], considering a chiral fourth generation quark . The upper limits at 68% (darker blue) and 95% (lighter blue) CL on the mass are depicted as a function of the CKM mixing , freely varied over  GeV/ and , respectively. The solid (dashed) curve denotes the upper bound under which and ( ) bound states can form, as defined by relation (6).