Photoproduction Cross Sections for ${\pi }^{+}$ and $K^{+}$ Mesons at 3.4 to 4.0 GeV and Their Comparison with $\mathrm{SU}\left(3\right)\mathrm{}$

The differential cross sections for the photoproduction reactions $\gamma +p\to {\pi }^{+}+n$, $\gamma +p\to K^{+}+{\Lambda }^0$, and $\gamma +p\to K^{+}+{\Sigma }^0$ have ben measured for incident laboratory photon energies between 3.4 and 4.0 GeV and for meson center-of-mass angles from about 25° to 45°. The reactions were studied by observing only the charged mesons. The momenta, velocities, and angles of the mesons were measured with a magnetic spectrometer, and the equivalent of nearly monochromatic gamma rays was obtained by performing bremsstrahlung subtractions. The cross sections agree with the inequality predicted from unbroken $\mathrm{SU}\left(3\right)\mathrm{}$. The measured behavior of $\frac{d\sigma }{\mathrm{dt}}$ as a function of $t$ shows similarities to that observed in studies of mesonnucleon scattering.