Large-transverse-momentum processes: the ISR as a gluon collider

TL;DR

The paper discusses how the ISR collider significantly advanced understanding of the strong interaction and QCD by probing high-energy gluon interactions, complementing fixed-target experiments and paving the way for future colliders.

Contribution

It highlights the unique role of the ISR as a gluon collider that provided valuable data on hadron structure and strong interactions, which was not possible with other accelerators.

Findings

ISR provided unique gluon interaction data

Complemented fixed-target experiments in hadron structure studies

Contributed to the development of QCD understanding

Abstract

It is argued that, contrary to what is often said, large-transverse-momentum hadronic processes studied at the ISR have made a significant contribution to the understanding of the strong interaction and, in particular, to the development of quantum chromodynamics. In their unique role as a gluon collider the ISR have provided information that no other accelerator could have directly offered. They allowed one to probe high values of the centre-of-mass energy that were not available to fixed-target experiments. The latter, however, were more flexible and, together, they allowed for powerful explorations of the hadron structure and of the relevant dynamics in sectors such as inclusive particle production, direct photon production, and jet structure studies. It remains true that, rightly so, the ISR will be mostly remembered as the founders of a lineage that includes the proton-antiproton colliders and, today, the LHC.