# Dirac fermion

In physics, a **Dirac fermion** is spin ^{1}⁄_{2} particle (a fermion) which is different from its antiparticle. The vast majority of fermions – perhaps all – fall under this category.

## DescriptionEdit

In particle physics all fermions in the standard model have distinct antiparticles (*perhaps* excepting neutrinos) and hence are Dirac fermions. They are named for Paul Dirac, and can be modeled with the Dirac equation.

A Dirac fermion is equivalent to two Weyl fermions.^{[1]} The counterpart to a Dirac fermion is a Majorana fermion, a particle that must be its own antiparticle.

## Dirac fermion quasi-particlesEdit

In condensed matter physics, low-energy excitations in graphene and topological insulators, among others, are fermionic quasiparticles described by a pseudo-relativistic Dirac equation.

## See alsoEdit

- Dirac spinor, a wavefunction-like description of a Dirac fermion
- Majorana fermion, an alternate category of fermion, possibly describing neutrinos
- Spinor, mathematical details

## ReferencesEdit

**^**Shifman, Mikhail (1999). "ITEP Lectures on Particle Physics and Field Theory".**1**: 292. ISBN 9789810239480. Cite journal requires`|journal=`

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