Parton Dynamics at PHENIX

TL;DR

This paper discusses measurements of transverse single-spin asymmetries at PHENIX, indicating partonic transverse momentum effects, and reviews the new MPC-EX detector's role in further exploring these phenomena.

Contribution

It introduces the MPC-EX detector and outlines its potential to deepen understanding of partonic transverse momentum effects at PHENIX.

Findings

Transverse single-spin asymmetries of about 10% observed at RHIC energies.

First data collected with the MPC-EX detector for studying asymmetries.

Ongoing work aims to measure intrinsic partonic transverse momentum.

Abstract

Investigating partonic interactions is one of the primary goals of the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). RHIC is specially tailored for studying intrinsic partonic spin-momentum correlations due to its unique ability to collide polarized proton beams. Transverse single-spin asymmetries of order 10% have been measured in PHENIX at center of mass energies from 62.4 GeV to 200 GeV, similar to previous measurements. These results indicate that there exist partonic transverse momentum effects within the proton and/or within the process of hadronization. The MPC-EX, a new silicon-tungsten preshower detector at PHENIX, has taken data for the first time this year with the intent of shedding further light on the origins of these asymmetries. A review of the status of the detector and of future planned measurements will be presented. An overview of ongoing work by PHENIX aimed at measuring intrinsic partonic transverse momentum will be discussed.