Characterizing the away-side jet with robust flow background subtraction via two- and three-particle correlations in Au+Au collisions at sNN=200Â GeV in STAR

We report measurements of jet correlations in Au+Au collisions at sNN=200 GeV by the STAR experiment. We devise novel methods to subtract flow background using data. Two-particle away-side jet correlation width is studied as a function of centrality and associated particle pT. The width is found to increase with centrality at modest to high associated particle pT. The increase can arise from jet-medium modifications, event averaging of away-side jets deflected by medium flow, and/or simply nuclear kT broadening. To further discriminate various physics mechanisms, a three-particle correlation analysis is conducted. A significant signal of nuclear kT effect and/or jets deflected by medium flow is observed.