Comment on the recent COMPASS data on the spin structure function g_1

TL;DR

This paper analyzes recent COMPASS data on the spin structure function g_1, suggesting it favors positive initial gluon densities but is difficult to interpret conclusively due to data limitations.

Contribution

It provides a critical assessment of the COMPASS data's implications for initial parton densities, highlighting interpretative challenges and a tentative preference for positive gluon densities.

Findings

Data better agree with positive gluon densities

Interpretation is challenging due to data form

Tentative preference for positive gluon densities

Abstract

We examine the recent COMPASS data on the spin structure function g_1 singlet. We show that it is rather difficult to use the data in the present form in order to draw conclusions on the initial parton densities. However, our tentative estimate is that the data better agree with positive rather than negative initial gluon densities.