Paper detail

Minijet deformation and charge-independent angular correlations on momentum subspace $(η,ϕ)$ in Au-Au collisions at $\sqrt{s_{NN}}$ = 130 GeV

First measurements of charge-independent correlations on angular difference variables $η_1 - η_2$ (pseudorapidity) and $ϕ_1 - ϕ_2$ (azimuth) are presented for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|η| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. Strong charge-independent angular correlations are observed associated with jet-like structures and elliptic flow. The width of the jet-like peak on $η_1 - η_2$ increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. New methods of jet analysis introduced here provide evidence for nonperturbative QCD medium effects in heavy ion collisions.