Quantum field theory (QFT) is a theoretical framework in fundamental physics that unifies classical field theory, special relativity, and quantum mechanics into a single formalism for describing particles as excitations of underlying fields. It arose from the limitation that non-relativistic quantum mechanics (via the Schrödinger equation) cannot consistently describe phenomena such as spontaneous emission, since it is not compatible with special relativity. QFT is built from fields, particles as field quanta, Lagrangian/Hamiltonian dynamics, Feynman diagrams, renormalization, and symmetry principles, and splits into sub-theories such as quantum electrodynamics (QED, electromagnetic interactions) and quantum chromodynamics (QCD, strong interactions between quarks and gluons).
Quantum field theory (QFT) is a theoretical framework in fundamental physics that unifies classical field theory, special relativity, and quantum mechanics into a single formalism for describing part…