Abstract
In magnetized proto-neutron stars, neutrino cross sections depend asymmetrically on the neutrino momenta because of parity violation. However, these asymmetric opacities do not induce any asymmetric flux in the bulk interior of the star where neutrinos are nearly in thermal equilibrium. Consequently, parity violation in neutrino absorption and scattering can only give rise to asymmetric neutrino flux above the neutrino-matter decoupling layer. We estimate that a dipole field of B ~ 1015-1016 G is necessary to produce kick velocity of order of a few hundred km s-1 using this mechanism.