Δ-isobar effects onM2strength inPb208

The strength distribution of the $2^{-}$ states in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ is calculated including the $\Delta$-isobar quenching effects. The theoretical $B \mathrm{}\left(M2\mathrm{}\right)\mathrm{}$ values up to 8 MeV are dominated by the orbital angular momentum part of the $M2\mathrm{}$ operator. Therefore we find only little quenching in this energy region owing to the $\Delta$-particle nucleon-hole admixtures.