Interaction Vertex

An interaction vertex is a point in a Feynman diagram where particles meet and interact, representing a fundamental event in particle physics. It indicates how particles, like electrons, quarks, or photons, exchange energy or force, transforming into different particles or altering their states. Think of it as a junction where the fundamental building blocks of matter influence each other according to the laws of quantum mechanics. These vertices help physicists visualize and calculate the probabilities of various particle interactions that occur in high-energy experiments or the universe itself.