Advanced Quantum Theory is a concised, comprehensive, well-organized text based on the techniques used in theoretical elementary particle physics and extended to other branches of modern physics as well. While it is especially valuable reading for students and professors of physics, a less cursory survey should aid the nonspecialist in mastering the principles and calculational tools that probe the quantum nature of the fundamental forces. The initial application is to nonrelativistic scattering graphs encountered in atomic, solid state, and nuclear physics. Then, focusing on relativistic Feynman Diagrams and their construction in lowest order--applied to electromagnetic, strong, weak, and gravitational interactions -- this bestseller also covers relativistic quantum theory based on group theoretical language, scattering theory, and finite parts of higher order graphs. This new edition includes two chapters on the quark model at low energies.