Search for narrow dibaryon resonances in neutral pion photoproduction from the deuteron

The reaction $\gamma d \to \pi^0X$ has been measured with TAPS at MAMI in the energy range $E_\gamma = 140$–300 MeV. Using the Glasgow tagging spectrometer a photon energy resolution of 0.8 MeV was achieved. The energy excitation functions of integral and differential total cross-sections show no structures of statistical significance $> 2\sigma$. Upper limits for the production of narrow isoscalar or isovector dibaryons with masses $m \leq 2100$ MeV/c$^2$ were deduced. They are in the range 2–5 $\mu$b averaged over the 0.8 MeV energy resolution