Tevatron mass limits for heavy quarks decaying via flavor changing neutral currents

Abstract

The dimuon and dielectron data from the Tevatron p̅p collider are used to probe for heavy quarks, which decay dominantly via flavor changing neutral currents. Depending on whether the FCNC decay occurs at the tree or loop level, one gets a lower mass limit of 85 or 75 GeV. The former applies to singlet, vector doublet, and mirror-type quarks while the latter applies to a lefthanded quark doublet of the fourth generation.