CPT Violation: Theory and Phenomenology

Invariance under the combined transformations of CPT (in any order) is guaranteed in Quantum Field Theory in flat space times due to a basic theorem (CPT Theorem). The currently used formalism of particle physics phenomenology is based on this theorem. However, there may be violations of the basic underlying assumptions of this theorem in models of quantum gravity, namely Lorentz covariance, unitarity and/or locality of interactions. This may lead to observable (in principle) effects of CPT violation. Since there is no single figure of merit for this potential violation,the respective phenomenology is rather complex. In this review I classify the possible ways of CPT violation, and I describe briefly their phenomenology, in both terrestrial and astrophysical experiments, including antimatter factories, neutral mesons and neutrinos, and discuss the various sensitivities.