Understanding the nature of the heavy pentaquarks and searching for them in pion-induced reactions

TL;DR

This paper explores how triangle singularities in pion-induced reactions can mimic pentaquark signals, highlighting the importance of process-dependent searches to clarify the nature of exotic heavy pentaquarks.

Contribution

It analyzes the role of triangle singularities in pion-induced reactions and suggests that process-dependent searches are crucial for distinguishing genuine pentaquarks from kinematic effects.

Findings

Triangle singularities can produce peaks similar to pentaquark signals.

Process dependence of TS effects can help differentiate genuine states.

Ambiguities in pentaquark identification are highlighted.

Abstract

We investigate the reaction $\pi^- p \to \pi^- J/\psi p$ via the open-charm hadron rescattering diagrams. Due to the presence of the triangle singularity (TS) in the rescattering amplitudes, the TS peaks can simulate the pentaquark-like resonances arising in the $J/\psi p$ invariant mass distributions, which may bring ambiguities on our understanding of the nature of the exotic states. Searching for the heavy pentaquark in different processes may help us to clarify the ambiguities, because of the highly process-dependent characteristic of the TS mechanism.