Gauge anomaly cancellations in SU(2)_L \times U(1)_Y Electroweak theory   on the lattice
  We consider the cohomological classification of the 4+2-dimensional topological field, which is proposed by L\"uscher, for SU(2)_L \times U(1)_Y electroweak theory. The dependence on the admissible abelian gauge field of U(1)_Y is determined through topological argument, with SU(2)_L gauge field fixed as background. We then show the exact cancellation of the local gauge anomaly of the mixed type {SU(2)_L}^2 \times U(1)_Y at finite lattice spacing, as well as {U(1)_Y}^3, using the pseudo reality of SU(2)_L and the anomaly cancellation conditions in the electroweak theory given in terms of the hyper-charges of U(1)_Y. 
Yoshio Kikukawa, Yoichi Nakayama