Fate of the Tetraquark Candidate Zc(3900) from Lattice QCD

TL;DR

This study uses lattice QCD to analyze the nature of the $Z_{c}(3900)$, concluding it is a threshold cusp rather than a conventional resonance, based on coupled-channel scattering simulations.

Contribution

The paper provides the first lattice QCD analysis of the $Z_{c}(3900)$, revealing its nature as a threshold cusp through coupled-channel scattering methods.

Findings

$Z_{c}(3900)$ is likely a threshold cusp, not a resonance.

Off-diagonal couplings dominate the interaction.

Lattice QCD simulations support the cusp interpretation.

Abstract

The possible exotic meson $Z_{c}(3900)$, found in $e^+ e^-$ reactions, is studied by the method of coupled-channel scattering in lattice QCD. The interaction among $\pi J/\psi$, $\rho \eta_{c}$ and $\bar{D}D^{*}$ channels is derived from (2+1)-flavor QCD simulations at $m_{\pi}=410$-$700$ MeV. The interaction is dominated by the off-diagonal $\pi J/\psi$-$\bar{D}D^{*}$ and $\rho \eta_{c}$-$\bar{D}D^{*}$ couplings, which indicates that the $Z_{c}(3900)$ is not a usual resonance but a threshold cusp. Semi-phenomenological analyses with the coupled-channel interaction are presented to confirm this conclusion.