In
supersymmetric
In a supersymmetric theory the equations for force and the equations for matter are identical. In theoretical and mathematical physics, any theory with this property has the principle of supersymmetry (SUSY). Dozens of supersymmetric theorie ...
extension to the
Standard Model
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying a ...
(SM) of
physics, a sfermion is a hypothetical
spin
Spin or spinning most often refers to:
* Spinning (textiles), the creation of yarn or thread by twisting fibers together, traditionally by hand spinning
* Spin, the rotation of an object around a central axis
* Spin (propaganda), an intentionally b ...
-0
superpartner particle (sparticle) of its associated
fermion
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 an ...
. Each particle has a superpartner with spin that differs by . Fermions in the SM have
spin- and, therefore, sfermions have spin 0.
The name 'sfermion' was formed by the general rule of prefixing an 's' to the name of its superpartner, denoting that it is a
scalar particle with spin 0. For instance, the
electron's superpartner is the
selectron and the
top quark's superpartner is the
stop squark
In particle physics, a stop squark, symbol , is the superpartner of the top quark as predicted by supersymmetry (SUSY). It is a sfermion, which means it is a spin-0 boson ( scalar boson). While the top quark is the heaviest known quark, the sto ...
.
One corollary from supersymmetry is that sparticles have the same
gauge numbers as their SM partners. This means that sparticle–particle pairs have the same
color charge,
weak isospin charge, and
hypercharge (and consequently
electric charge). Unbroken supersymmetry also implies that sparticle–particle pairs have the same mass. This is evidently not the case, since these sparticles would have already been detected. Thus, sparticles must have different masses from the particle partners and supersymmetry is said to be broken.
Fundamental sfermions
Squarks
Squarks (also quarkinos) are the superpartners of
quark
A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly o ...
s. These include the sup squark, sdown squark, scharm squark, sstrange squark,
stop squark
In particle physics, a stop squark, symbol , is the superpartner of the top quark as predicted by supersymmetry (SUSY). It is a sfermion, which means it is a spin-0 boson ( scalar boson). While the top quark is the heaviest known quark, the sto ...
, and sbottom squark.
Sleptons
Sleptons are the superpartners of
leptons. These include the selectron, smuon, stau, and their corresponding sneutrino flavors.
See also
*
Minimal Supersymmetric Standard Model (MSSM)
References
*
{{Particles
Supersymmetric quantum field theory
Hypothetical elementary particles
Bosons
Subatomic particles with spin 0