subatomic particle

A composite particle proton is made of two up quarks and one down quark, which are elementary particles.

In physics, a subatomic particle is a particle smaller than an atom. According to the Standard Model of particle physics, a subatomic particle can be a composite particle or an elementary particle. A composite particle, such as a proton or a neutron, is composed of other particles while an elementary particle, such as an electron, is not composed of other particles. Particle physics and nuclear physics study these particles and how they interact. Most force-carrying particles such as photons or gluons are called bosons and, although they have quanta of energy, do not have rest mass or discrete diameters (other than pure energy wavelength) and are unlike the former particles that have rest mass and cannot overlap or combine, which are called fermions. The W and Z bosons, however, are an exception to this rule and have relatively large rest masses at approximately 80 GeV/c and 90 GeV/c respectively.