Top-bottom doublet in the sphaleron background

We consider the top-bottom doublet in the background of the sphaleron for the realistic case of large non-degeneracy of fermion masses, in particular m_b=5 GeV and m_t=175 GeV. We propose an axially symmetric (r,\theta)-dependent ansatz for fermion fields and investigate the effects of the non-degeneracy on them. The exact solution is described, with an error less than 0.01\%, by a set of ten radial functions. We also propose an approximate solution, in the m_b/m_t\rightarrow 0 limit, with an error {\cal O}(m_b/m_t). We have found that the effects of non-degeneracy provide a \theta-dependence typically \sim 10\%.