Energy and System Size Dependence of Two- and Four-Particle ν2 Measurements in Heavy-Ion Collisions at √ˢᴺᴺ = 62.4 and 200 GeV and Their Implications on Flow Fluctuations and Nonflow
We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants ν2 ν2{2} and ν2{4}) for Au + Au and Cu + Cu collisions at center-of-mass energies √ˢᴺᴺ = 62.4 and 200 GeV. The difference between ν2{2}2 and ν2{4}2 is related to ν2fluctuations (σν2) and nonflow (δ2). We present an upper limit to σν2/ν2. Following the assumption that eccentricity fluctuations σε dominate ν2 fluctuations σν2/ν2 ≈ σε/ε we deduce the nonflow implied for several models of eccentricity fluctuations that would be required for consistency with ν2{2} and ν2{4}. We also present results on the ratio of ν2 to eccentricity
