Measurement of the beam asymmetry $\Sigma$ and the target asymmetry $T$ in the photoproduction of $\omega$ mesons off the proton using CLAS at Jefferson Laboratory

TL;DR

This paper reports the first measurement of the target asymmetry T and updates the photon-beam asymmetry Sigma in omega meson photoproduction off protons using CLAS, revealing resonance contributions and extending the data range.

Contribution

It provides the first measurement of the target asymmetry T in omega photoproduction and extends the photon-beam asymmetry Sigma data, enhancing understanding of resonance contributions.

Findings

Significant non-zero target asymmetry T observed, reaching 30-40%.

Photon-beam asymmetry Sigma agrees with previous data and extends the energy range.

Partial-wave analysis indicates contributions from s-channel resonances and t-channel processes.

Abstract

The photoproduction of $\omega$ mesons off the proton has been studied in the reaction $\gamma p\to p\,\omega$ using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target (FROST) in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry, $T$, has been measured in photoproduction from the decay $\omega\to\pi^+\pi^-\pi^0$, using a transversely-polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant non-zero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry, $\Sigma$, are also presented, which agree well with previous CLAS results and extend the world database up to 2.1 GeV. These data and additional $\omega$-photoproduction observables from CLAS were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from $s$-channel resonance production were found in addition to $t$-channel exchange processes.