Vector Meson Exchange and Radiative Nonleptonic Kaon Decays In ChPT

ChPT is a powerful tool to study low energy pseudoscalar mesons physics. After a short introduction to ChPT in chapter 1 and its application to radiative nonleptonic Kaon decays in chapter 2, we studied the contribution of vector meson exchang to the speci?c decay K_S ightarrow pi^0 pi^0 gamma gamma. We fixed two coupling coefficients of mathcal{O}(p^6) weak effective chiral Lagrangian by using Bose symmetry, gauge symmetry and two bound equations got from experiment NA48. We show that vector meson exchange in weak sector is dominant at mathcal{O}(p^6), and its contribution cancels the biggest contribution at mathcal{O}(p^4) about 60%.