Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. It is also called "high energy physics", because many elementary particles do not occur under normal circumstances in nature, but can be created and detected during energetic collisions of other particles, as is done in particle accelerators.
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Elementary particle
In particle physics, an elementary particle or fundamental particle is a not known to have substructure; that is, it is not known to be made up of smaller particles. If an elementary particle truly has no substructure, then it is one of the basic particles of the universe from which all larger particles are made. In the Standard Model, the quarks, leptons, and gauge bosons are elementary particles.
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Noun 1. the branch of physics that studies subatomic particles and their interactions (synonym) high-energy physics, high energy physics (hypernym) physics, physical science, natural philosophy (class) flavor, flavour