Chiral unitary theory: Application to nuclear problems

In this talk we briefly describe some basic elements of chiral perturbation theory, chi PT, and how the implementation of unitarity and other novel el ements lead to a better expansion of the T-matrix for meson-meson and meson -baryon interactions. Applications are then done to the pi pi interaction i n nuclear matter in the scalar and vector channels, antikaons in nuclei and K- atoms, and how the phi meson properties are changed in a nuclear medium .