Aggregation of autoregressive processes and long memory
  We study the aggregation of AR processes and generalized Ornstein-Uhlenbeck (OU) processes. Mixture of spectral densities with random poles are the main tool. In this context, we apply our results for the aggregation of doubly stochastic interactives processes, see Dacunha-Castelle and Fermin (2006). Thus, we study the relationship between aggregation of autoregressive processes and long memory considering complex interaction structures. We precise a very interesting qualitative phenomena: how the long memory creation depends on the poles concentration near to the boundary of stability (measured in the Prokhorov sense). Our results extends the results given by Oppenheim and Viano (2004), and highlight the importance of the angular dispersion measure of poles in the appearance of the long memory. 
Didier Dacunha-Castelle (1) and Lisandro J. Ferm\'in (1,2) ((1)   Universit\'e Paris Sud, (2) Universit\'e Paris Descartes)