Spin-Density Matrix Elements for Vector Meson Photoproduction at GlueX

TL;DR

This paper reports high-precision measurements of spin-density matrix elements for vector meson photoproduction at GlueX, providing crucial data to understand the production mechanisms and aid in the search for hybrid mesons.

Contribution

It presents the first detailed, high-statistics measurements of spin-density matrix elements for vector mesons in polarized photoproduction at GlueX.

Findings

Unprecedented statistical precision in spin-density matrix elements for the ρ(770) meson.

Enhanced understanding of the production mechanism of vector mesons.

Data will support the search for exotic hybrid mesons.

Abstract

The GlueX experiment at Jefferson Lab aims to study the light meson spectrum with an emphasis on the search for hybrid mesons. To this end, a linearly-polarized $9\,$GeV photon beam impinges on a hydrogen target contained within a detector with near-complete neutral and charged particle coverage. In 2018, the experiment completed its first phase of data taking in its design configuration and the quantity of analyzed data already exceed that of previous experiments for polarized photoproduction in this energy regime by orders of magnitude. Polarization observables such as spin-density matrix elements provide valuable input for the theoretical description of the production mechanism, which will be essential for the interpretation of possible exotic meson signals. We present results for the photoproduction of vector mesons, focusing on the unprecedented statistical precision of the spin-density matrix elements for the $\rho(770)$ meson.