Quantitative Constraints on the Transport Properties of Hot Partonic Matter from Semi-Inclusive Single High Transverse Momentum Pion Suppression in Au+Au collisions at sqrt(s_NN) = 200 GeV

TL;DR

This paper uses high transverse momentum pi^0 suppression data from Au+Au collisions at 200 GeV to quantitatively constrain models of parton energy loss in dense QCD matter, achieving 20-25% precision.

Contribution

It provides a systematic methodology to compare energy-loss models with experimental data, constraining key parameters of the medium with quantified uncertainties.

Findings

Constraints on initial color-charge density dN^g/dy within 20-25%

Constraints on medium transport coefficient <q^hat> within 20-25%

Constraints on initial energy-loss parameter epsilon_0 within 20-25%

Abstract

The PHENIX experiment has measured the suppression of semi-inclusive single high transverse momentum pi^0's in Au+Au collisions at sqrt(s_NN) = 200 GeV. The present understanding of this suppression is in terms of energy-loss of the parent (fragmenting) parton in a dense color-charge medium. We have performed a quantitative comparison between various parton energy-loss models and our experimental data. The statistical point-to-point uncorrelated as well as correlated systematic uncertainties are taken into account in the comparison. We detail this methodology and the resulting constraint on the model parameters, such as the initial color-charge density dN^g/dy, the medium transport coefficient <q^hat>, or the initial energy-loss parameter epsilon_0. We find that high transverse momentum pi^0 suppression in Au+Au collisions has sufficient precision to constrain these model dependent parameters at the +/1 20%-25% (one standard deviation) level. These constraints include only the experimental uncertainties, and further studies are needed to compute the corresponding theoretical uncertainties.