A study of the centrally produced 4pi channel in pp interactions at 450 GeV/c

TL;DR

This paper investigates the production of various mesonic states in proton-proton interactions at 450 GeV/c, identifying known and new states, and analyzing their production characteristics to distinguish between qqbar and non-qqbar states.

Contribution

It reports the observation of two new mesonic states and analyzes their production behavior, providing insights into gluonic states versus qqbar states in high-energy pp collisions.

Findings

Identification of eta2(1620) and eta2(1875) states.

Evidence for a broad scalar f0(2000).

Discovery of two states at 1.45 GeV and 1.9 GeV with non-qqbar behavior.

Abstract

The reaction pp -> pf (pi+pi-pi+pi-) ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT filter applied. In addition to the well known f1(1285) there is evidence for two JPC=2-+ states called the eta2(1620) and eta2(1875) and a broad scalar called the f0(2000). The production of these states as a function of the dPT kinematical filter shows the behaviour expected for qqbar states. In contrast, there is evidence for two states at 1.45 GeV and at 1.9 GeV which do not show the behaviour observed for qqbar states.