Discrete Symmetries: Introduction

This lecture introduces discrete symmetries in Quantum Field Theory (QFT), such as parity and time reversal, which play a fundamental role in QFT by conserving degeneracy of solutions. It also discusses charge conjugation, a symmetry that does not act on space-time coordinates. The theoretical results regarding the invariance under Lorentz transformations, locality, and CPT symmetry are explored, along with the implications of accidental symmetries. The lecture concludes with a discussion on how experimental observations confirm the symmetries of nature and the breaking of these symmetries in interactions.