Chiral Symmetry Restoration in Nuclei

The recent discovery of deeply bound pionic states in heavy nuclei, using pion transfer reactions of the type ²⁰⁶Pb (d,³He) π^- ⊗ ²⁰⁵Pb is reviewed. Binding energies and widths of pionic 1s- and 2p- states are determined for ²⁰⁷Pb and recently also ²⁰⁵Pb. The characteristic narrowness of these states, generated by a strong repulsive s-wave pion-nucleus interaction is naturally explained by a reduced and density dependent pion decay constant, which in turn reflects the change of the QCD vacuum structure in dense matter.