Parton Momentum Distribution at the Moment of Jet-Parton Collision

TL;DR

This paper extracts the initial parton momentum distribution at jet-parton collision time from STAR data, revealing a thermal transverse profile and a rapidity plateau with sharp boundaries, providing insights into early collision dynamics.

Contribution

It introduces a method to determine the early parton momentum distribution using ridge particle data, highlighting a thermal transverse profile and a rapidity plateau structure.

Findings

Parton momentum distribution has a thermal-like transverse momentum profile.

Rapidity distribution exhibits a plateau at mid-rapidities with sharp boundaries.

Results provide insights into the initial state of partons in heavy-ion collisions.

Abstract

We extract the early parton momentum distribution using the STAR Collaboration data of ridge particles associated with a near-side jet in central AuAu collisions at \sqrt{s_{NN}}=200 GeV. 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.