Gluons and the eta' nucleon coupling constant

TL;DR

This paper derives an effective chiral Lagrangian incorporating gluonic effects to understand eta and eta' nucleon interactions, highlighting how the axial anomaly influences experimental extraction of the eta' nucleon coupling constant.

Contribution

It introduces a novel contact term in the effective Lagrangian due to gluonic degrees of freedom affecting eta' production in proton-proton reactions.

Findings

Gluonic effects induce a contact term in eta' production reactions.

Implications for extracting the eta' nucleon coupling constant from experiments.

Enhanced understanding of axial anomaly's role in low-energy hadronic interactions.

Abstract

We derive the effective chiral Lagrangian for low energy eta--nucleon and eta'--nucleon interactions and show that gluonic degrees of freedom, via the axial anomaly, induce a contact term in the pp -> pp eta and pp -> pp eta' reactions. We then discuss the consequences for the extraction of g_{eta'NN} from experimental data.