Standard Model

The Standard Model of particle physics is a theory of three of the four known fundamental interactions and the elementary particles that take part in these interactions. These particles make up all visible matter in the universe. The standard model is a gauge theory of the electroweak and strong interactions with the gauge group SU(3)×SU(2)×U(1).

Every high energy physics experiment carried out since the mid-20th century has eventually yielded findings consistent with the Standard Model. Still, the Standard Model falls short of being a complete theory of fundamental interactions because it does not include gravity, dark matter, or dark energy. It isn't quite a complete description of leptons either, because it does not describe nonzero neutrino masses, although simple natural extensions do.

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