Quantum States and Quantum Numbers

This lecture delves into the concept of quantum states and quantum numbers, exploring how states are labeled by momentum, spin, and other quantum numbers. The lecture covers the sum over all possible quantum numbers to generate all possible states, emphasizing the importance of internal charges and relativistic constraints. The instructor explains the significance of mass states and the identity in the space of states, highlighting the role of complex conjugates and the spectral density. The lecture also discusses the time-ordered correlator, the field strength tensor, and the interactions of massless particles, showcasing the constraints imposed by gauge invariance and conservation laws.