Long-range particle correlations and wavelets

The problem of Ions-range correlations of particles produced in high-energy collisions is discussed. Long-range correlations may involve large groups of particles, as exemplified by ring-like and elliptic flow shapes of indiv idual high-multiplicity events in the polar plus azimuthal angle planes. To identify such structures, the wavelet analysis method has been proposed an d applied to some central lead-lead collisions at energy of 158 GeV per nuc leon. In the present paper, previous attempts at obtaining long-range corre lations are discussed and recent wavelet analysis results for high energy n ucleus-nucleus interactions are reviewed.