Quantum-Classical Correspondence in Microscopic and Mesoscopic Complex Collisions

We propose a novel method to study quantum-classical correspondence in complex, e.g., heavy-ion, atomic, molecular, and atomic cluster collisions. The many-body rotating wave packets are formed spontaneously and their stability is due to the slow decoherence between highly excited strongly overlapping states of the intermediate complex. The phenomenon is illustrated by analyzing the 12C+24Mg collision. The significant devia tions from the random-matrix theory are reproduced in terms of the macroscopically rotating molecule formed in this collision