[Physics] the difference between QFT and elementary particle physics


I'm a little unclear as to how QFT differs from Elementary particle physics. They both use pictorials of Feynman graphs, is it that Elementary particle physics assumes the point particle perspective, while QFT treats them as fields?

Best Answer

Quantum Field Theory is the framework that we normally use to study particle physics. It is the idea that the world is described by fields and each field can move into excited states which correspond to particles.

Since we are working with fields, you not constricted to a fixed particle number as in Quantum Mechanics. This is very useful since due to $E=mc^2$, particles constantly appear and disappear in the real world.

Particle physics on the other hand, is the study of the particles that make up our world. Since QFT's are terrific at describing Nature, we use them to describe particle physics; they are tool we need to study particle physics. However, some people study QFT for the sake of QFT since its a very deep and subtle subject.

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