Nucleon

In physics a nucleon is a collective name for the two baryons the neutron and the proton. They are constituents of the atomic nucleus and till the 1960s were thought to be elementary. In those days their interactions (now called internucleon interactions) defined strong interactions. Now they are known to be composite particles, made of quarks and gluons. Understanding the nucleons' properties is one of the major goals of quantum chromodynamics, the modern theory of strong interactions.

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The proton is the lightest baryon and its stability is a measure of baryon number conservation. The proton's lifetime thus puts strong constraints on speculative theories which try to extend the standard model of particle physics.

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The neutron decays into the protons through the weak decay. The two are members of an isospin I=1/2 doublet.

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Physics: Physics (from the Greek, φυσικός (phusikos), "natural", and φύσις (phusis), "nature") is the science of the natural world in the broadest sense, dealing with matter and energy and the fundamental forces of nature that govern the interaction...

Baryon: In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called nucleons), as well as a number of unstable, heavier particles (called hyperons). The term "baryon" is derived from the Greek barys, meaning "heavy," as they are heavier tha...

Proton: :For alternative meanings see proton (disambiguation)....