In
supersymmetric extension to the
Standard Model
The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) in the unive ...
(SM) of
physics
Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...
, a sfermion is a hypothetical
spin-0
superpartner particle (sparticle) of its associated
fermion
In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin (spin 1/2, spin , Spin (physics)#Higher spins, spin , etc.) and obey the Pauli exclusion principle. These particles i ...
. 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
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...
's superpartner is the
selectron and the
top quark's superpartner is the
stop squark.
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
In particle physics, the hypercharge (a portmanteau of hyperonic and charge (physics), charge) ''Y'' of a subatomic particle, particle is a quantum number conserved under the strong interaction. The concept of hypercharge provides a single charg ...
(and consequently
electric charge
Electric charge (symbol ''q'', sometimes ''Q'') is a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative''. Like charges repel each other and ...
). 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 nucleus, atomic nuclei ...
s. These include the sup squark, sdown squark, scharm squark, sstrange squark,
stop squark, 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