Axino
Encyclopedia
The axino is a hypothetical elementary particle
predicted by some theories of particle physics
. 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 superpartner
for the axion, the axino, and a bosonic superpartner, the axion. 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
.
Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles. If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which...
predicted by some theories of particle physics
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...
. Peccei-Quinn theory
Peccei-Quinn theory
In particle physics, the Peccei–Quinn theory is the best known proposal for the resolution of the strong CP problem. The theory proposes that the QCD Lagrangian be extended with a CP-violating term known as the θ parameter...
attempts to explain the observed phenomenon known as the strong CP problem by introducing a hypothetical real scalar particle called the axion
Axion
The axion is a hypothetical elementary particle postulated by the Peccei-Quinn theory in 1977 to resolve the strong CP problem in quantum chromodynamics...
. Adding supersymmetry
Supersymmetry
In particle physics, supersymmetry is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners...
to the model predicts the existence of a fermionic superpartner
Superpartner
In particle physics, a superpartner is a hypothetical elementary particle. Supersymmetry is one of the synergistic theories in current high-energy physics which predicts the existence of these "shadow" particles....
for the axion, the axino, and a bosonic superpartner, the axion. They are all bundled up in a chiral superfield
Chiral superfield
In theoretical physics, one often analyzes theories with supersymmetry in which chiral superfields play an important role. In four dimensions, the minimal N=1 supersymmetry may be written using the notion of superspace...
.
The axino has been predicted to be the lightest supersymmetric particle
Lightest Supersymmetric Particle
In particle physics, the Lightest Supersymmetric Particle is the generic name given to the lightest of the additional hypothetical particles found in supersymmetric models. In models with R-parity conservation, the LSP is stable. There is extensive observational evidence for an additional...
in such a model. In part due to this property, it is considered a candidate for the composition of dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
.