Gaugino
Encyclopedia
In particle physics
, a gaugino is the hypothetical superpartner
of a gauge field, as predicted by gauge theory
combined with supersymmetry
. They are fermion
s.
In the minimal supersymmetric extension of the standard model
the following gauginos exist:
Gauginos mix with higgsino
s, the superpartners of the Higgs Field's degrees of freedom, to form linear combinations ("mass eigenstates") called neutralino
s (electrically neutral) and chargino
s (electrically charged). In many models the lightest neutralino, sometimes called photino, is stable. In that case it is a WIMP and a candidate for dark matter
.
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...
, a gaugino is the hypothetical 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....
of a gauge field, as predicted by gauge theory
Gauge theory
In physics, gauge invariance is the property of a field theory in which different configurations of the underlying fundamental but unobservable fields result in identical observable quantities. A theory with such a property is called a gauge theory...
combined with 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...
. They are fermion
Fermion
In particle physics, a fermion is any particle which obeys the Fermi–Dirac statistics . Fermions contrast with bosons which obey Bose–Einstein statistics....
s.
In the minimal supersymmetric extension of the standard model
Standard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
the following gauginos exist:
- The gluinoGluinoA gluino is the hypothetical supersymmetric partner of a gluon. Gluinos are expected by supersymmetry theorists to be pair produced in particle accelerators such as the Large Hadron Collider if they exist....
(symbol ) is the superpartner of the gluonGluonGluons are elementary particles which act as the exchange particles for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles....
, and hence carries color chargeColor chargeIn particle physics, color charge is a property of quarks and gluons that is related to the particles' strong interactions in the theory of quantum chromodynamics . Color charge has analogies with the notion of electric charge of particles, but because of the mathematical complications of QCD,...
. - The gravitinoGravitinoThe gravitino is the supersymmetric partner of the graviton, as predicted by theories combining general relativity and supersymmetry; i.e. supergravity theories...
(symbol ) is the supersymmetric partner of the gravitonGravitonIn physics, the graviton is a hypothetical elementary particle that mediates the force of gravitation in the framework of quantum field theory. If it exists, the graviton must be massless and must have a spin of 2...
. - The winos (symbol ) and the zino (symbol ) are the superpartners of the W and Z BosonsW and Z bosonsThe W and Z bosons are the elementary particles that mediate the weak interaction; their symbols are , and . The W bosons have a positive and negative electric charge of 1 elementary charge respectively and are each other's antiparticle. The Z boson is electrically neutral and its own...
of the SU(2)L gauge fields. - The bino is the superpartner of the U(1) gauge field corresponding to weak hyperchargeWeak hyperchargeThe weak hypercharge in particle physics is a conserved quantum number relating the electrical charge and the third component of weak isospin, and is similar to the Gell-Mann–Nishijima formula for the hypercharge of strong interactions...
.
Gauginos mix with higgsino
Higgsino
In particle physics, a Higgsino, symbol , is the hypothetical superpartner of the Higgs boson, as predicted by supersymmetry. The Higgsino is a Dirac fermion and that is a weak isodoublet with hypercharge half under the Standard Model gauge symmetries...
s, the superpartners of the Higgs Field's degrees of freedom, to form linear combinations ("mass eigenstates") called neutralino
Neutralino
In particle physics, the neutralino is a hypothetical particle predicted by supersymmetry. There are four neutralinos that are fermions and are electrically neutral, the lightest of which is typically stable...
s (electrically neutral) and chargino
Chargino
In particle physics, the chargino is a hypothetical particle which refers to the mass eigenstates of a charged superpartner, i.e. any new electrically charged fermion predicted by supersymmetry. They are linear combinations of the charged wino and charged higgsinos...
s (electrically charged). In many models the lightest neutralino, sometimes called photino, is stable. In that case it is a WIMP and a candidate for 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...
.