The Polarization Behavior of Relativistic Synchrotron Jets

We describe a geometric model for synchrotron radiation from blazar jets, involving multiple emission zones with turbulent magnetic fields and a transient core with a helical B field. Including the effects of jet divergence, particle cooling and the Relativistic PA rotation (RPAR) to the observer frame, we find polarization behavior consistent with recent data from monitoring campaigns. We predict that under some circumstances multi-$\pi$ rotation phases should exhibit relativistically-induced steps in rate $d{\rm PA}/dt$ and modulation in polarization $\Pi$ that can be helpful in pinning down the jet $\Gamma$ and $\theta_{\rm obs}$. Also, RPAR enhances waveband differences that will be particularly interesting for comparing radio, optical and, soon, X-ray PA and $\Pi$ variations.