  We discuss the gauge dependence of fermion mass definition and physical
result under the conventional on-shell mass renormalization scheme and the
recently proposed pole mass renormalization scheme in standard model. By the
two-loop calculations of top quark's mass counterterm and the cross section of
physical process $W^{-}W^{+}\to b\bar{b}$ we strictly prove that the on-shell
mass renormalization scheme makes fermion mass definition and the physical
result gauge dependent at the first time, while we don't find such gauge
dependence in the pole mass renormalization scheme. Besides, our calculation
also shows the difference of the physical result between the two mass
renormalization schemes cannot be neglected at two-loop level.

High Energy Physics - Phenomenology