Upper Limit on the Photoproduction Cross Section of the Spin-Exotic $\pi_1(1600)$

TL;DR

This study sets the first upper limits on the photoproduction cross sections of the spin-exotic $(1600)$ meson using GlueX data, indicating $(1600)$ is difficult to produce via photon interactions.

Contribution

It provides the first experimental upper limits on the photoproduction of the $(1600)$ meson, combining experimental data with lattice decay width calculations.

Findings

Established upper limits on $(1600)$ photoproduction cross sections.

Identified $(1600)$ photoproduction as challenging with current methods.

Suggested $(1600)$ production via $'$ decay channels as most promising.

Abstract

The spin-exotic hybrid meson $\pi_{1}(1600)$ is predicted to have a large decay rate to the $\omega\pi\pi$ final state. Using 76.6~pb$^{-1}$ of data collected with the GlueX detector, we measure the cross sections for the reactions $\gamma p \to \omega \pi^+ \pi^- p$, $\gamma p \to \omega \pi^0 \pi^0 p$, and $\gamma p\to\omega\pi^-\pi^0\Delta^{++}$ in the range $E_\gamma =$ 8-10 GeV. Using isospin conservation, we set the first upper limits on the photoproduction cross sections of the $\pi^{0}_{1}(1600)$ and $\pi^{-}_{1}(1600)$. We combine these limits with lattice calculations of decay widths and find that photoproduction of $\eta'\pi$ is the most sensitive two-body system to search for the $\pi_1(1600)$.