Non-flow correlations in a cluster model
  We derive analytical forms for nonflow contributions from cluster correlation to the measurement of two-particle elliptic flow (v2{2}). We estimate nonflow contribution from rho->pi+pi decays and find it is negative but not a major contributor to the nonflow effect in v2{2}. We also estimate nonflow contribution from the recent STAR measurement of two-particle angular correlations. 
Quan Wang and Fuqiang Wang