PWA of 3pi Final States and a Search for the pi1(1600)

TL;DR

This paper presents a partial wave analysis of 3-pion final states from high-energy pion-proton interactions, confirming known mesons and investigating the exotic pi1(1600), which appears not to be supported by the data.

Contribution

It provides a detailed PWA of 3pi systems and critically examines the evidence for the exotic pi1(1600) meson, highlighting the importance of including multiple decay modes in the analysis.

Findings

Stable signals for known mesons like a1(1260), a2(1320), pi2(1670)

No conclusive evidence for pi1(1600) when additional decay modes are considered

Emphasizes the robustness of conventional meson signals in PWA

Abstract

Partial wave analyses (PWA) of the 3pi systems in the reactions pi- p --> pi+ pi- pi- p (the ``charged'' mode) and pi- p --> pi- pi0 pi0 p (the ``neutral'' mode) with an 18.3 GeV/c pion beam were performed using high statistics data from the E852 experiment. Conventional signals, such as the a1(1260), the a2(1320), and the pi2(1670), were found to be remarkably stable to the choice of waves included in the fit. In contrast, possible evidence for the pi1(1600) in the JPC = 1-+ exotic wave amplitude disappears when additional decay modes of conventional mesons (especially those of the pi2(1670)) are included in the PWA fit.