Parton Momentum Distribution at the Moment of Jet-Parton Collisions

The early parton momentum distribution is extracted by using the STAR collaboration data of ridge particles associated with a near-side jet in central AuAu collisions at √s_NN=200GeV. The ridge particles are identified as medium partons kicked by the jet near the surface and they carry direct information on the parton momentum distribution at the moment of jet-parton collisions. The extracted parton momentum distribution has a thermal-like transverse momentum distribution but a rapidity plateau structure with a relatively flat rapidity distribution at mid-rapidities with sharp kinematic boundaries at large rapidities that depend on the transverse momentum