Momentum Kick Model Analysis of PHENIX Near-Side Ridge Data and Photon Jet

TL;DR

This paper applies the momentum kick model to analyze PHENIX near-side ridge data in central Au+Au collisions, revealing that the ridge particles reflect early parton distributions and involve non-perturbative pomeron exchanges.

Contribution

It demonstrates that the momentum kick model effectively describes the ridge data and uncovers details of the early parton momentum distribution and non-perturbative scattering mechanisms.

Findings

Ridge particles carry information on early parton distributions.

Early partons have a thermal-like transverse distribution.

Parton-parton scattering involves non-perturbative pomeron exchange.

Abstract

We analyze PHENIX near-side ridge data for central Au+Au collisions at \sqrt{s_{NN}}=200 GeV with the momentum kick model, in which 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 early parton momentum distribution and the magnitude of the momentum kick. We find that the PHENIX ridge data can be described well by the momentum kick model and the extracted early partons momentum distribution has a thermal-like transverse distribution and a rapidity plateau structure. We also find that the parton-parton scattering between the jet parton and the medium parton involves the exchange of a non-perturbative pomeron, for jet partons in momentum range considered in the near-side ridge measurements.