The gluon polarization $\Delta G/G$ at COMPASS

TL;DR

The paper reports on the first measurement of the gluon polarization in the nucleon using high transverse momentum hadron pairs at the COMPASS experiment, aiming to understand the spin structure of the proton.

Contribution

It presents the initial results of measuring gluon polarization via double helicity asymmetry in high pT hadron pair production at COMPASS, a novel approach in this context.

Findings

First asymmetry measurement using high pT hadron pairs

Provides data on gluon polarization in the nucleon

Supports ongoing efforts to resolve the proton spin puzzle

Abstract

The COMPASS experiment will determine the gluon polarization in the nucleon $\Delta G/G$ from the double helicity asymmetry measured in the scattering of a 160 GeV muon beam on a longitudinally polarized deuteron target, by selecting the photon-gluon fusion reaction. This reaction can be tagged either by the production of open charm, or by the production of high $p_T$ hadron pairs. The first asymmetry obtained with the latter method is presented.