Phase synchronization and polarization ordering of globally coupled oscillators.

We introduce a prototype model for globally coupled oscillators in which each element is given an oscillation frequency and a preferential oscillation direction (polarization), both randomly distributed. We found two collective transitions: to phase synchronization and to polarization ordering. Introducing a global-phase and polarization order parameters, we show that the transition to global-phase synchrony is found when the coupling overcomes a critical value and that polarization order enhancement cannot take place before global-phase synchrony. We develop a self-consistent theory to determine both order parameters in good agreement with numerical results.