Coherent Compton scattering on light nuclei in the $\Delta$-resonance region is studied in the impulse approximation and is shown to be a sensitive probe of the in-medium properties of the $\Delta$ resonance. The elementary amplitude on a single nucleon is calculated from the unitary K-matrix approach developed previously. Modifications of the properties of the $\Delta$ resonance due to the nuclear medium are accounted for through the self-energy operator of the $\Delta ,$ calculated from the one-pion loop. The dominant medium effects such as the Pauli blocking, mean-field modification of the nucleon and $\Delta$ masses, and particle-hole excitations in the pion propagator are consistently included in nuclear matter.

• Received 29 August 2001

DOI:https://doi.org/10.1103/PhysRevC.65.014613