Quantum field theory (QFT) is used in particle physics to construct physical models of subatomic particles. QFT treats particles as excited states (also called quanta) of their underlying quantum fields, which are more fundamental than the particles.
Source:
[1] Wikipedia Contributors. “Quantum Field Theory.” Wikipedia, Wikimedia Foundation, 23 Dec. 2020, en.wikipedia.org/wiki/Quantum_field_theory. Accessed 4 Jan. 2021.