Why density matrices in QFT are calculated only by going to Euclidean metric?
Answers
Explanation:
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics[1]:xi (but notably not general relativity's description of gravity) and is used to construct physical models of subatomic particles (in particle physics) and quasiparticles (in condensed matter physics).
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics[1]:xi (but notably not general relativity's description of gravity) and is used to construct physical models of subatomic particles (in particle physics) and quasiparticles (in condensed matter physics).QFT treats particles as excited states (also called quanta) of their underlying fields, which are more fundamental than the particles. Interactions between particles are described by interaction terms in the Lagrangian involving their corresponding fields. Each interaction can be visually represented by Feynman diagrams, which are formal computational tools, in the process of relativistic perturbation theory.