  In the momentum kick model, a near-side jet emerges 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 carry direct information on the magnitude
of the momentum kick and the initial parton momentum distribution at the moment
of jet-(medium parton) collisions. The initial parton momentum distribution
extracted from the STAR ridge data for central AuAu collisions at
\sqrt{s_{NN}}=200 GeV has a thermal-like transverse momentum distribution and a
rapidity plateau structure with a relatively flat distribution at mid-rapidity
and sharp kinematic boundaries at large rapidities. Such a rapidity plateau
structure may arise from particle production in flux tubes, as color charges
and anti-color charges separate at high energies. The centrality dependence of
the ridge yield and the degree of jet quenching can be consistently described
by the momentum kick model.
