Photoproduction of Meson and Baryon Resonances at Energies up to 5.8 GeV

TLDR

Photoproduction of vector mesons and Δ isobars is examined using various theoretical models. The study surveys experimental procedures and resonance production in quasi‑two‑body photoproduction reactions. Using a hydrogen bubble chamber, the authors analyzed ~31,000 events (0.3–5.8 GeV) to measure differential cross sections and density matrix elements for vector meson and Δ production. Cross sections for multiple photoproduction channels—including π, η, vector mesons, and Δ resonances—were measured across the 0.3–5.8 GeV photon energy range.

Abstract

In a study of photoproduction at photon energies between 0.3 and 5.8 GeV in a hydrogen bubble chamber, approximately 31 000 events with three, five, or seven outgoing charged particles were analyzed. This paper gives a survey of the experimental procedure and of resonance production in quasi-two-body reactions. The cross sections for the processes $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}\mathrm{pV} (V={\ensuremath{\rho}}^{0},\ensuremath{\omega},\ensuremath{\phi})$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}p\ensuremath{\eta}$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{X}^{0}$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}$, and $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{0}{\ensuremath{\pi}}^{+}$ have been measured as a function of the photon energy. For reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\rho}}^{0}$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}p\ensuremath{\omega}$, and $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}$, the differential cross sections and density matrix elements are given for various intervals of the photon energy. The photoproduction of vector mesons and $\ensuremath{\Delta}$ isobars is discussed in terms of several models.