Manifold reconnection and diffusion in strong chaos

We analyse diffusion across a reconnecting zone in a regime of strong chaos . Numerical estimates from the angular correlation functions averaged over a suitable set of phase-space initial conditions are compared to a local di ffusion coefficient obtained using Fick's law. It emerges that the diffusio n coefficient is enhanced from small to larger values as successive reconne ction-like processes or more usual bifurcations take place. This feature is illustrated using a quadratic nontwist map. (C) 2000 Elsevier Science B.V. All rights reserved.