Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC

We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from $sqrt{s_{NN}}=7.7$ GeV to 200 GeV. The third harmonic $v_3^2{2}=langle cos3(phi_1-phi_2)rangle$, where $phi_1-phi_2$ is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs $Deltaeta = eta_1-eta_2$. Non-zero {vthree} is directly related to the previously observed large-$Deltaeta$ narrow-$Deltaphi$ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity Quark Gluon Plasma (QGP) phase. For sufficiently central collisions, $v_3^2{2}$ persist down to an energy of 7.7 GeV suggesting that QGP may be created even in these low energy collisions. In peripheral collisions at these low energies however, $v_3^2{2}$ is consistent with zero. When scaled by pseudorapidity density of charged particle multiplicity per participating nucleon pair, $v_3^2{2}$ for central collisions shows a minimum near {snn}$=20$ GeV.