Cluster model and two-particle pseudorapidity and azimuthal correlations in $p+p$ and $A+A$ collisions

Cluster models have had consistent success in explaining correlations among final state particles in hadronic multiparticle production [1]. In this talk two-particle correlations are presented for simulated $p+p$ and $A+A$ collisions based on the picture of particle production via cluster decay. The modification of correlations due to radial flow of clusters is also studied. Features are found to be similar to those observed experimentally.\\[4pt] [1] B. Alver {\it et al}., (PHOBOS Collaboration), Phys. Rev. C {\bf 75}, 05493 (2007); R. E. Ansorge {\it et al}., (UA5 Collaboration), Z. Phys. C {\bf 37}, 191 (1988); L. Fo\`{a}, Phys. Rep. {\bf 22}, 1 (1975).