Subatomic particle

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/c2 and 90 GeV/c2 respectively.

Experiments show that light can behave like a stream of particles (called photons) as well as exhibiting wave-like properties. This led to the concept of wave–particle duality to reflect that quantum-scale particles behave both like particles and like waves; they are occasionally called wavicles to reflect this.

Another concept, the uncertainty principle, states that some of their properties taken together, such as their simultaneous position and momentum, cannot be measured exactly.

Interactions of particles in the framework of quantum field theory are understood as creation and annihilation of quanta of corresponding fundamental interactions.