The axino is a hypothetical
elementary particle
In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions ( quarks, leptons, a ...
predicted by some theories of
particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
.
Peccei–Quinn theory attempts to explain the observed phenomenon known as the
strong CP problem by introducing a hypothetical real scalar particle called the
axion. Adding
supersymmetry to the model predicts the existence of a
fermionic
In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Generally, it has a half-odd-integer spin: spin , spin , etc. In addition, these particles obey the Pauli exclusion principle. Fermions include all quarks and ...
superpartner
In particle physics, a superpartner (also sparticle) is a class of hypothetical elementary particles predicted by supersymmetry, which, among other applications, is one of the well-studied ways to extend the standard model of high-energy physics.
...
for the axion, the axino, and a bosonic superpartner, the ''saxion''. They are all bundled up in a
chiral superfield.
The axino has been predicted to be the
lightest supersymmetric particle in such a model. In part due to this property, it is considered a candidate for the composition of
dark matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not a ...
.
The supermultiplet containing an axion and axino has been suggested as the origin of supersymmetry breaking, where the supermultiplet gains an F-term expectation value.
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References
Dark matter
Fermions
Supersymmetric quantum field theory
Hypothetical elementary particles
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