Dissipation and fragmentation of low- Q 2 scattered partons in Au−Au collisions at RHIC

Two-particle correlations and event-wise fluctuations in transverse momentum p tare reported for Au−Au collisions at √s NN =62 and 200 GeV on pseudorapidity η and azimuth ϕ. Distributions of all pairs of particles (no leading trigger particle) reveal jet-like correlations, or peaks at pair-wise opening angles of order 1 radian or less. The width of this same-side correlation peak increases dramatically on pseudorapidity and decreases on azimuth for increasing collision centrality. Evolution of the same-side peak with centrality suggests dissipation of low-Q 2 partons via strong couplign to an expanding bulk medium. p t correlations, which provide access to temperature and/or velocity distributions in the colliding system, are also presented.