Cobimaximal Mixing with Dirac Neutrinos

If neutrinos are Dirac, the conditions for cobimaximal mixing, i.e. $\theta_{23}=\pi/4$ and $\delta_{CP}=\pm \pi/2$ in the $3 \times 3$ neutrino mixing matrix, are derived. One example with $A_4$ symmetry and radiative Dirac neutrino masses is presented.