Direct top quark production at hadron colliders as a probe of new physics

We examine the effect of an anomalous flavor-changing chromomagnetic moment which allows direct top quark production (two partons combining into an unaccompanied single top quark in the $s$ channel) at hadron colliders. We consider both $t-c-g$ and $t-u-g$ couplings. We find that the anomalous charm quark coupling parameter ${\kappa }_c/\Lambda$ can be measured down to $0.06{\mathrm{}\mathrm{TeV}}^{-1}$ $\left(0.009\mathrm{}{\mathrm{}\mathrm{TeV}}^{-1}\right)$ at the Fermilab Tevatron with the Main Injector upgrade (CERN LHC). The anomalous up quark coupling parameter ${\kappa }_u/\Lambda$ can be measured to $0.02{\mathrm{}\mathrm{TeV}}^{-1}$ $\left(0.003\mathrm{}{\mathrm{}\mathrm{TeV}}^{-1}\right)$ at the Tevatron (LHC).