Determination of the forward Compton scattering amplitudes for C and Pb
  The forward Compton scattering amplitude for carbon and lead have been calculated from total photoabsorption cross section data by using dispersion relations. The results show a large difference between the scattering amplitudes for nuclei and the free nucleon, above the $\Delta $ region. The forward Compton scattering cross sections have been calculated and compared with the available data. The Weise sum rule is discussed together with the prediction of a recent theoretical model. 
A. Deppman, N. Bianchi, E. De Sanctis, M. Mirazita, V. Muccifora, P.   Rossi (INFN- Laboratori Nazionali di Frascati)