Amplitude analysis and the nature of the Zc(3900)

TL;DR

This paper discusses how amplitude analysis can help determine the nature of the Zc(3900) peak, but current data are insufficient to distinguish between different theoretical models, highlighting the need for higher-statistics measurements.

Contribution

It proposes a method of amplitude analysis to differentiate between QCD states, virtual states, and kinematical effects in the Zc(3900) peak.

Findings

Current data cannot distinguish the hypotheses

Amplitude analysis can constrain models of XYZ states

Future high-statistics data will clarify the nature of Zc(3900)

Abstract

The microscopic nature of the XYZ states remains an unsettled topic. We show how a thorough amplitude analysis of the data can help constraining models of these states. Specifically, we consider the case of the Zc(3900) peak and discuss possible scenarios of a QCD state, virtual state, or a kinematical enhancement. We conclude that current data are not precise enough to distinguish between these hypotheses, however, the method we propose, when applied to the forthcoming high-statistics measurements should shed light on the nature of these exotic enhancements.