Can Parity Violation in Neutrino Transport Lead to Pulsar Kicks?

In magnetized proto-neutron stars, neutrino cross sections depend asymmetrically on the neutrino momenta due to 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. The kick velocity is substantially reduced from previous estimates, requiring a dipole field $B \sim 10^{16}$~G to get $v_{kick}$ of order a few hundred km~s$^{-1}$.