Acceleration of highest energy cosmic rays

Relativistic outflows carrying large scale magnetic fields have large inductive potential and may accelerate protons to ultra high energies. We discuss a novel scheme of UHECR acceleration due to drifts in cylindrically collimated, sheared extragalactic jets. A particle advected by such a jet is in an unstable equilibrium if ${\bf B} \cdot \nabla \times {\bf v}< 0$, so that kinetic drift along velocity shear leads to fast, regular energy gain. Acceleration rate does reach absolute theoretical maximum of inverse gyro-frequency. In addition, highest rigidity particles are accelerated most efficiently, implying the dominance of light nuclei at highest energies.