  When a particle crosses a region of space where the curvature radius of the
magnetic field line shrinks below its gyroradius $r_{\rm g}$, it experiences a
non-adiabatic (magnetic moment violating) change in pitch angle. The present
paper carries that observation into magnetohydrodynamic (MHD) turbulence to
examine the influence of intermittent, sharp bends of the magnetic field lines
on particle transport. On the basis of dedicated measurements in a simulation
of incompressible turbulence, it is argued that regions of sufficiently large
curvature exist in sufficient numbers on all scales to promote scattering. The
parallel mean free path predicted by the power-law statistics of the curvature
strength scales in proportion to $r_{\rm g}^{0.3}\,\ell_{\rm c}^{0.7}$
($\ell_{\rm c}$ coherence scale of the turbulence), which is of direct interest
for cosmic-ray phenomenology. Particle tracking in that numerical simulation
confirms that the magnetic moment diffuses through localized, violent
interactions, in agreement with the above picture. Correspondingly, the overall
transport process is non-Brownian up to length scales $\gtrsim\ell_{\rm c}$.
