Editing Fermion (section)

==Composite fermions==
{{see also|List of particles#Composite particles}}

Composite particles (such as [[hadron]]s, nuclei, and atoms) can be bosons or fermions depending on their constituents. More precisely, because of the relation between spin and statistics, a particle containing an odd number of fermions is itself a fermion. It will have half-integer spin.

Examples include the following:
*A baryon, such as the proton or neutron, contains three fermionic quarks.
*The nucleus of a [[carbon-13]] atom contains six protons and seven neutrons.
*The atom [[helium-3]] (<sup>3</sup>He) consists of two protons, one neutron, and two electrons. The [[deuterium]] atom consists of one proton, one neutron, and one electron.

The number of bosons within a composite particle made up of simple particles bound with a potential has no effect on whether it is a boson or a fermion.

Fermionic or bosonic behavior of a composite particle (or system) is only seen at large (compared to size of the system) distances. At proximity, where spatial structure begins to be important, a composite particle (or system) behaves according to its constituent makeup.

Fermions can exhibit bosonic behavior when they become loosely bound in pairs. This is the origin of superconductivity and the [[superfluid]]ity of helium-3: in superconducting materials, electrons interact through the exchange of [[phonon]]s, forming [[Cooper pair]]s, while in helium-3, Cooper pairs are formed via spin fluctuations.

The quasiparticles of the [[fractional quantum Hall effect]] are also known as [[composite fermions]]; they consist of electrons with an even number of quantized vortices attached to them.