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We investigate inclusive ω photoproduction off complex nuclei, concentrating on the feasibility to examine a possible in-medium change of the ω meson properties by observing the π 0 γ invariant mass spectrum. The simulations are performed by means of a BUU transport model including a full coupled-channel treatment of the final state interactions. In-medium changes of the ω spectral density are found to yield a moderate modification of the observables as compared to the situation in free space. Also the effects of a momentum dependence of the strong ω potential are discussed.

A description of low-energy scattering of pions and nuclei within a BUU transport model is presented. Implementing different scenarios of medium modifications, the mean free path of pions in nuclear matter at low momenta and pion absorption reactions on nuclei have been studied and compared to data and to results obtained via quantum mechanical scattering theory. We show that even in a regime of a long pionic wave length the semi-classical transport model is still a reliable framework for pion kinetic energies greater than ≈ 20 − 30 MeV. Results are presented on π-absorption cross sections in the regime of 10 MeV ≤ T π kin ≤ 130 MeV and on photon-induced ππ production at incident beam energies of 400 − 500 MeV.

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