Near threshold anomalous transport in the standard map

Anomalous transport is investigated near threshold in the standard map. Ver y long time flights, and a large anomaly in the transport, are shown to be associated with a new form of multi-island structures causing orbit stickin g. The phase space structure of these traps, and the exponents of the chara cteristic long time tails associated with them are determined. In general t hese structures are very complex, but some cases, consisting of layers of i slands, allow simple modeling. (C) 1998 American Institute of Physics. [S10 54-1500(98)01403-7].