Photoproduction of ω Mesons off the Proton

Abstract

The differential cross sections and unpolarized spin-density matrix elements for the reaction $\gamma p\to p\omega$ were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV. These observables were measured from the radiative decay of the $\omega$ meson, $\omega \to {\pi }^0\gamma$. The cross sections cover the full angular range and show the full extent of the $t$-channel forward rise. The overall shape of the angular distributions in the differential cross sections and unpolarized spin-density matrix elements are in fair agreement with previous data. In addition, for the first time, a beam of linearly-polarized tagged photons in the energy range from 1150 MeV to 1650 MeV was used to extract polarized spin-density matrix elements. These data were included in the Bonn-Gatchina partial wave analysis (PWA). The dominant contribution to $\omega$ photoproduction near threshold was found to be the $3/2^{+}$ partial wave, which is primarily due to the sub-threshold $N(1720)3/2^{+}$ resonance. At higher energies, pomeron-exchange was found to dominate whereas $\pi$-exchange remained small. These $t$-channel contributions as well as further contributions from nucleon resonances were necessary to describe the entire dataset: the $1/2^{-}$, $3/2^{-}$, and $5/2^{+}$ partial waves were also found to contribute significantly.

arXiv comment8 pages, 5 figures, accepted for publication in Physics Letters B

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Cited by in corpus (22)

• Light Baryon Spectroscopy
• Photoproduction Reactions and Non-Strange Baryon Spectroscopy
• $N^{\ast }$ decays to $N\omega$ from new data on $\gamma p\to \omega p$
• Scatter fraction of the J-PET tomography scanner
• Measurement of the helicity asymmetry $E$ in $\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0$ photoproduction
• Overview of the software architecture and data flow for the J-PET tomography device
• Overview of the software architecture and data flow for the J-PET tomography device
• Nucleon resonances in $\gamma p\to \omega p$ reaction
• $\omega N$ scattering length from $\omega$ photoproduction on the proton near the threshold
• Mapping chiral symmetry breaking in the excited baryon spectrum
• Measurement of double polarisation asymmetries in $\omega$-photoproduction
• 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
• Photon beam asymmetry $\Sigma$ in the reaction $\vec{\gamma }p\to p\omega$ for $E_{\gamma }$ = 1.152 to 1.876 GeV
• Pomeron, nucleon-resonance, and $(0^{+},0^{-},1^{+})$-meson contributions in $\varphi$-meson photoproduction
• Features of $\omega$ photoproduction off nucleon target at forward angles : Dominance of $\pi$ exchange with Regge cuts and scaling of differential cross sections
• Photoproduction of $\eta$ mesons off the proton for $1.2<E_{\gamma }<4.7$ GeV using CLAS at Jefferson Laboratory
• Features of $\omega$ photoproduction off proton target at backward angles : Role of nucleon Reggeon in $u$-channel with parton contributions
• Formation of eta'(958) bound states by (gamma, d) reaction
• Search for Pentaquark Theta+ in Hadronic Reaction at J-PARC
• Vertex operators for production of baryon resonances in nucleon-gamma collisions with preserving gauge invariance and analyticity
• Populating Low-Spin States in Radioactive Nuclei to Measure Magnetic Moments Using the Transient Field Technique
• First Measurements of the Double-Polarization Observables $F$, $P$, and $H$ in $\omega$ Photoproduction off Transversely Polarized Protons in the $N^{\ast }$ Resonance Region