Multipion and Strange-Particle Photoproduction on Protons at Energies up to 5.8 GeV

Abstract

In a study of photoproduction at photon energies between 0.3 and 5.8 GeV in a hydrogen bubble chamber, approximately 1.7 million pictures containing about 31 000 events with three or more outgoing charged particles were analyzed. This is the second of two final reports on this experiment. Distributions of effective masses are given for the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}N3\ensuremath{\pi}, N4\ensuremath{\pi}, N5\ensuremath{\pi}$. Cross sections for the production of $\ensuremath{\Delta}(1236)$ and $\ensuremath{\rho}$ via $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\Delta}\ensuremath{\rho}, \ensuremath{\Delta}2\ensuremath{\pi}, \ensuremath{\Delta}3\ensuremath{\pi}, \ensuremath{\Delta}4\ensuremath{\pi}, N\ensuremath{\pi}\ensuremath{\rho}, \mathrm{and} N2\ensuremath{\pi}\ensuremath{\rho}$ and of various other reactions are reported. From the reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{++}{\ensuremath{\rho}}^{\ensuremath{-}}$, an upper limit for the radiative decay width of ${\ensuremath{\rho}}^{\ensuremath{-}}$, $\ensuremath{\Gamma}({\ensuremath{\rho}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma})<0.24$ MeV, is obtained (90% confidence). For the four-pion decay mode of the ${\ensuremath{\rho}}^{0}$, an upper limit of $\frac{\ensuremath{\Gamma}({\ensuremath{\rho}}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}})}{\ensuremath{\Gamma}({\ensuremath{\rho}}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})}<0.0015$ is found (90% confidence). The photoproduction of strange particles is discussed and cross sections for $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\Lambda}{K}^{+}, \ensuremath{\Sigma}K, \ensuremath{\Lambda}K\ensuremath{\pi}, \ensuremath{\Sigma}K\ensuremath{\pi}, \mathrm{and} \ensuremath{\Lambda}K\ensuremath{\pi}\ensuremath{\pi}$ are presented. Production of $\ensuremath{\Sigma}(1385)$ was observed.