In
particle physicsParticle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. It is also called high energy physics, because many elementary particles do not occur under normal circumstances in nature, but can be created and detected...
, a
superpartner (also
sparticle) is a hypothetical
elementary particleIn 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...
. The word
superpartner is a portmanteau of the words
supersymmetry and
partner (
sparticle is a portmanteau of
supersymmetry and
particle).
SupersymmetryIn 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...
is one of the cutting-edge
theoriesThe term theory has two broad sets of meanings, one used in the empirical sciences and the other used in philosophy, mathematics, logic, and across other fields in the humanities. There is considerable difference and even dispute across academic disciplines as to the proper usages of the term...
in current high-energy physics which predicts the existence of these "shadow" particles. According to the theory, each
fermionIn particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. In contrast to bosons, which have Bose-Einstein statistics, only one fermion can occupy a quantum state at a given time; this is the Pauli Exclusion Principle. Thus, if more than one...
should have a partner
bosonIn particle physics, bosons are particles which obey Bose–Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein. In contrast to fermions, which obey Fermi-Dirac statistics, several bosons can occupy the same quantum state. Thus, bosons with the same energy can occupy the...
, the fermion's superpartner and each boson should have a partner fermion.
In
particle physicsParticle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. It is also called high energy physics, because many elementary particles do not occur under normal circumstances in nature, but can be created and detected...
, a
superpartner (also
sparticle) is a hypothetical
elementary particleIn 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...
. The word
superpartner is a portmanteau of the words
supersymmetry and
partner (
sparticle is a portmanteau of
supersymmetry and
particle).
SupersymmetryIn 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...
is one of the cutting-edge
theoriesThe term theory has two broad sets of meanings, one used in the empirical sciences and the other used in philosophy, mathematics, logic, and across other fields in the humanities. There is considerable difference and even dispute across academic disciplines as to the proper usages of the term...
in current high-energy physics which predicts the existence of these "shadow" particles. According to the theory, each
fermionIn particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. In contrast to bosons, which have Bose-Einstein statistics, only one fermion can occupy a quantum state at a given time; this is the Pauli Exclusion Principle. Thus, if more than one...
should have a partner
bosonIn particle physics, bosons are particles which obey Bose–Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein. In contrast to fermions, which obey Fermi-Dirac statistics, several bosons can occupy the same quantum state. Thus, bosons with the same energy can occupy the...
, the fermion's superpartner and each boson should have a partner fermion. When the more familiar
leptonLeptons are a family of elementary particles, alongside quarks and gauge bosons . Like quarks, leptons are fermions and are subject to the electromagnetic force, the gravitational force, and weak interaction, but unlike quarks, leptons do not participate in the strong interaction.There are six...
s,
photonIn physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s, and
quarkA quark is an 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. Due to a phenomenon known as color confinement, quarks are never found in...
s were produced in the
Big BangThe Big Bang is the cosmological model of the initial conditions and subsequent development of the Universe that is supported by the most comprehensive and accurate explanations from current scientific evidence and observation...
, each one was accompanied by a matching sparticle: sleptons, photinos and squarks. This state of affairs occurred at a time when the
universeThe Universe comprises everything that physically exists, the entirety of space and time, all forms of matter and energy, and the physical laws and constants that govern them...
was undergoing a rapid phase change, and theorists believe this state of affairs lasted only some ten trillionth of a ten trillionth of a nanosecond (10
-35 seconds) before the particles we see now "condensed" out and froze into space-time. Sparticles have not existed naturally since that time.
Exact
unbroken supersymmetry would predict that a particle and its superpartners would have the same mass. No superpartners of the
Standard ModelThe Standard Model of particle physics is a theory of three of the four known fundamental interactions and the elementary particles that take part in these interactions. These particles make up all visible matter in the universe...
particles have yet been found. This may indicate that supersymmetry is incorrect, or it may also be the result of the fact that supersymmetry is not an exact,
unbroken symmetry of nature. If a superpartner is found, its mass would determine the scale at which supersymmetry is broken.
For particles that are real scalars (such as an
axionThe axion is a hypothetical elementary particle postulated by the Peccei-Quinn theory in 1977 to resolve the strong-CP problem in quantum chromodynamics . In 2005, an experimental search by the PVLAS collaboration reported results suggesting axion detection, but new experiments performed by the...
), there is a fermion superpartner as well as a second, real scalar field. For axions, these particles are often referred to as axinos and saxions.
In extended supersymmetry there may be more than one superparticle for a given particle. For instance, with two copies of supersymmetry in four dimensions, a photon would have two fermion superpartners and a scalar superpartner.
In zero dimensions (often known as
matrix mechanicsMatrix mechanics is a formulation of quantum mechanics created by Werner Heisenberg, Max Born, and Pascual Jordan in 1925.Matrix mechanics was the first complete and correct definition of quantum mechanics. It extended the Bohr Model by describing how the quantum jumps occur. It did so by...
), it is possible to have supersymmetry, but no superpartners. However, this is the only situation where supersymmetry does not imply the existence of superpartners.
However, if this theory is correct, it should be possible to recreate these particles in high-energy
particle acceleratorA particle accelerator is a device that uses electric fields to propel ions or charged subatomic particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator...
s. Doing so will not be an easy task; these particles may have masses up to a thousand times greater than their corresponding "real" particles. Until recently, colliders did not have the power to create these supermassive particles, but the newly built
Large Hadron ColliderThe Large Hadron Collider is the world's largest and highest-energy particle accelerator intended to collide opposing particle beams of either protons at an energy of 7 TeV per particle or lead nuclei at an energy of 574 TeV per nucleus...
at
CERNThe European Organization for Nuclear Research , known as CERN , , is the world's largest particle physics laboratory, situated in the northwest suburbs of Geneva on the Franco–Swiss border, established in 1954...
in
SwitzerlandSwitzerland , officially the Swiss Confederation , is a federal republic consisting of 26 states named cantons, with Bern as the seat of the federal authorities...
and
FranceFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
will be able to achieve collisions in the 14 TeV (tera-electron-volt) range, which is more than adequate to determine if these superpartner particles exist.
See also
- Chargino
The chargino is a hypothetical supersymmetric particle. It 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....
- Gluino
A gluino is the hypothetical supersymmetric partner of a gluon g. Gluinos are Majorana fermions and interact via the strong force as an octet of color...
- Gravitino
The gravitino is the supersymmetric partner of the graviton, as predicted by theories combining general relativity and supersymmetry; i.e. supergravity theories...
as a superpartner of the hypothetical gravitonIn physics, the graviton is a hypothetical elementary particle that mediates the force of gravity in the framework of quantum field theory. If it exists, the graviton must be massless and must have a spin of 2 In physics, the graviton is a hypothetical elementary particle that mediates the force...
- Neutralino
In particle physics, the neutralino is a hypothetical particle, part of the doubling of the menagerie of particles predicted by supersymmetric theories...
- Sfermion
In particle physics, a sfermion is a sparticle of the class of integer spin superpartners of ordinary fermions appearing in supersymmetric extensions to the Standard Model . Thus, the sfermions include the squarks and the sleptons...
- An Exceptionally Simple Theory of Everything
An Exceptionally Simple Theory of Everything is a preprint proposing a basis for a unified field theory, named E8 Theory, which attempts to describe all known fundamental interactions in physics, and to stand as a possible theory of everything...
External links