Abstract
In the momentum kick model, a near-side jet parton occurs near the surface, kicks medium partons, loses energy, and fragments into the trigger particle and fragmentation products. The kicked medium partons subsequently materialize as the observed ridge particles which cary direct information on the magnitude of the momentum kick and the initial parton momentum distribution at the moment of jet-parton collision. The initial parton momentum distribution, extracted from the STAR ridge data for central Au-Au collisions at \sqrt{s_NN} = 200 GeV, has a thermal-like transverse momentum distribution, but a non-Gaussian, relatively flat rapidity distribution at mid-rapidity with sharp kinematic boundaries at large rapidities. The degree of jet quenching and the centrality dependence of the ridge yield can also be described by the momentum kick model.
