Fermion zero-modes of a new constrained instanton in Yang-Mills-Higgs theory

Self-consistent Ansaetze are presented for the left- and right-handed isodoublet fermion zero-modes of the constrained instanton Istar in the vacuum sector of euclidean SU(2) Yang-Mills-Higgs theory. These left- and right-handed fermion wave functions do not coincide and, most likely, have maxima at different positions. This may be important for the fermion zero-mode contribution to the euclidean 4-point Green's function in chiral Yang-Mills-Higgs theory and the high-energy behaviour of fermion-fermion scattering processes.