Gradient Approach to the Sphaleron Barrier
  We apply the gradient approach to obtain a path over the sphaleron barrier and to demonstrate the fermionic level crossing phenomenon. Neglecting the mixing angle dependence and assuming that the fermions of a doublet are degenerate in mass we employ spherically symmetric ans\"atze for the fields. The gradient path over the barrier is smooth, even for large values of the Higgs boson mass or of the fermion mass, where the extremal energy path bifurcates. 
Guido Nolte and Jutta Kunz