Direct Mass Limits for Chiral Fourth-Generation Quarks in All Mixing Scenarios

Original · EN

Present limits on chiral fourth-generation quark masses mb' and mₜ' are broadly generalized and strengthened by combining both t' and b' decays and considering the full range of t' and b' flavor-mixing scenarios (with the lighter generations). Various characteristic mass-splitting choices are considered. With mₜ' > mb' we find that CDF limits on the b' mass vary by no more than 10-20% with any choice of flavor-mixing, while for the t' mass, we typically find stronger bounds, in some cases up to mₜ' > 430 GeV. For mb' > mₜ' we find mb' > 380 - 430 GeV, depending on the flavor-mixing and the size of the mₜ' - mb' mass splitting.