Photoexcitation of a quasibound delta-nucleus state of a nucleus

The photoproduction of negatively charged pions on a carbon nucleus in the (γ, π ^?, p) and (γ, π ^?, pp) reactions is studied experimentally. The results of the respective measurements are explained on the basis of a model that assumes the formation of an intermediate quasibound delta-nucleus state (delta nucleus) that decays via the emission of a pion and a nucleon. The delta-nucleus mass and width are estimated for the example of ¹¹B_Δ.