particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...

, a hyperon is any

baryon In particle physics, a baryon is a type of composite particle, composite subatomic particle that contains an odd number of valence quarks, conventionally three. proton, Protons and neutron, neutrons are examples of baryons; because baryons are ...

containing one or more

strange quark The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons (), ...

s, but no

charm Charm or Charms may refer to: Arts and entertainment * The Charms, an American garage rock band * Otis Williams and the Charms, an American doo-wop group * The Charm (Bubba Sparxxx album), ''The Charm'' (Bubba Sparxxx album), 2006 * Charm (Danny! ...

, bottom, or

top quark The top quark, sometimes also referred to as the truth quark, (symbol: t) is the most massive of all observed elementary particles. It derives its mass from its coupling to the Higgs field. This coupling is very close to unity; in the Standard ...

s. This form of matter may exist in a stable form within the core of some

neutron star A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...

s. Hyperons are sometimes generically represented by the symbol Y.

History and research

The first research into hyperons happened in the 1950s and spurred physicists on to the creation of an organized classification of particles. The term was coined by French physicist

Louis Leprince-Ringuet Louis Leprince-Ringuet (27 March 1901, in Alès – 23 December 2000, in Paris) was a French physicist, telecommunications engineer, essayist and historian of science. Leprince-Ringuet advocated strongly for the creation of the European O ...

in 1953, and announced for the first time at the cosmic ray conference at

Bagnères de Bigorre Bagnères is part of the name of three towns in France, all in the Pyrenees: *Argelès-Bagnères, Hautes-Pyrénées Department *Bagnères-de-Bigorre, Hautes-Pyrénées Department *Bagnères-de-Luchon Bagnères-de-Luchon (; ), also referred to as ...

in July of that year, agreed upon by Leprince-Ringuet, Bruno Rossi, C.F. Powell, William B. Fretter and

Bernard Peters Bernard Peters (born Bernhard Pietrowski in 1910 in Posen, Germany - February 2, 1993 in Copenhagen) was a nuclear physicist, with a specialty in cosmic radiation. He was a recipient of the Padma Bhushan, the third highest Indian civilian award ...

. Today, research in this area is carried out on data taken at many facilities around the world, including

CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Gene ...

Fermilab Fermi National Accelerator Laboratory (Fermilab), located in Batavia, Illinois, near Chicago, is a United States Department of Energy United States Department of Energy National Labs, national laboratory specializing in high-energy particle phys ...

SLAC SLAC National Accelerator Laboratory, originally named the Stanford Linear Accelerator Center, is a federally funded research and development center in Menlo Park, California, United States. Founded in 1962, the laboratory is now sponsored ...

JLAB GroovyLab, formerly jLab, is a numerical computational environment implemented in Java. The main scripting engine of GroovyLab is GroovySci, an extension of Groovy. Additionally, the interpreted Groovy Scripts (similar to MATLAB) and dynamic l ...

Brookhaven National Laboratory Brookhaven National Laboratory (BNL) is a United States Department of Energy national laboratories, United States Department of Energy national laboratory located in Upton, New York, a hamlet of the Brookhaven, New York, Town of Brookhaven. It w ...

KEK , known as KEK, is a Japanese organization whose purpose is to operate the largest particle physics laboratory in Japan, situated in Tsukuba, Ibaraki prefecture. It was established in 1997. The term "KEK" is also used to refer to the laboratory ...

, GSI and others. Physics topics include searches for

CP violation In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge conjugation symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics s ...

, measurements of

spin Spin or spinning most often refers to: * Spin (physics) or particle spin, a fundamental property of elementary particles * Spin quantum number, a number which defines the value of a particle's spin * Spinning (textiles), the creation of yarn or thr ...

, studies of

excited state In quantum mechanics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Add ...

s (commonly referred to as ''spectroscopy''), and hunts for exotic forms such as

pentaquark A pentaquark is a human-made subatomic particle, consisting of four quarks and one antiquark bound together; they are not known to occur naturally, or exist outside of experiments specifically carried out to create them. As quarks have a bar ...

s and

dibaryon In particle physics, hexaquarks, alternatively known as sexaquarks, are a large family of hypothetical Bound state, particles, each particle consisting of six quarks or antiparticle, antiquarks of any Flavour (particle physics), flavours. Six const ...

Properties and behavior

Being baryons, all hyperons are

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 ...

s. That is, they have

half-integer In mathematics, a half-integer is a number of the form n + \tfrac, where n is an integer. For example, 4\tfrac12,\quad 7/2,\quad -\tfrac,\quad 8.5 are all ''half-integers''. The name "half-integer" is perhaps misleading, as each integer n is its ...

and obey

Fermi–Dirac statistics Fermi–Dirac statistics is a type of quantum statistics that applies to the physics of a system consisting of many non-interacting, identical particles that obey the Pauli exclusion principle. A result is the Fermi–Dirac distribution of part ...

. Hyperons all interact via the

strong nuclear force In nuclear physics and particle physics, the strong interaction, also called the strong force or strong nuclear force, is one of the four known fundamental interactions. It confines quarks into protons, neutrons, and other hadron particles, an ...

, making them types of

hadron In particle physics, a hadron is a composite subatomic particle made of two or more quarks held together by the strong nuclear force. Pronounced , the name is derived . They are analogous to molecules, which are held together by the electri ...

. They are composed of three light

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, at least one of which is a

, which makes them strange baryons. Excited hyperon resonances and ground-state hyperons with a '*' included in their notation decay via the

strong interaction In nuclear physics and particle physics, the strong interaction, also called the strong force or strong nuclear force, is one of the four known fundamental interaction, fundamental interactions. It confines Quark, quarks into proton, protons, n ...

. For as well as the lighter hyperons this decay mode is not possible given the particle masses and the conservation of flavor and

isospin In nuclear physics and particle physics, isospin (''I'') is a quantum number related to the up- and down quark content of the particle. Isospin is also known as isobaric spin or isotopic spin. Isospin symmetry is a subset of the flavour symmetr ...

necessary in strong interactions. Instead, these decay weakly with non-conserved parity. An exception to this is the which decays electromagnetically into Λ on account of carrying the same flavor quantum numbers. The type of interaction through which these decays occur determine the average lifetime, which is why weakly decaying hyperons are significantly more long-lived than those that decay through strong or electromagnetic interactions.

List

Notes: * Since

strangeness In particle physics, strangeness (symbol ''S'') is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic interactions that occur in a short period of time. The strangeness of a ...

is conserved by the

s, some ground-state hyperons cannot decay strongly. However, they do participate in strong interactions. * may also decay on rare occurrences via these processes: *: → + + *: → + + * and are also known as "cascade" hyperons, since they go through a two-step cascading decay into a

nucleon In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number. Until the 1960s, nucleons were thought to be ele ...

. * The has a

baryon number In particle physics, the baryon number (B) is an additive quantum number of a system. It is defined as B = \frac(n_\text - n_), where is the number of quarks, and is the number of antiquarks. Baryons (three quarks) have B = +1, mesons (one q ...

of +1 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 ...

of −2, giving it strangeness of −3. It takes multiple flavor-changing weak decays for it to decay into a proton or neutron.

Murray Gell-Mann Murray Gell-Mann (; September 15, 1929 – May 24, 2019) was an American theoretical physicist who played a preeminent role in the development of the theory of elementary particles. Gell-Mann introduced the concept of quarks as the funda ...

's and

Yuval Ne'eman Yuval Ne'eman (; 14 May 1925 – 26 April 2006) was an Israeli theoretical physicist, military scientist, and politician. He was Minister of Science and Development in the 1980s and early 1990s. He was the President of Tel Aviv University ...

SU(3) In mathematics, the special unitary group of degree , denoted , is the Lie group of unitary matrices with determinant 1. The matrices of the more general unitary group may have complex determinants with absolute value 1, rather than real 1 i ...

model (sometimes called the Eightfold Way) predicted this hyperon's existence, mass and that it will only undergo weak decay processes. Experimental evidence for its existence was discovered in 1964 at

. Further examples of its formation and observation using

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies to contain them in well-defined particle beam, beams. Small accelerators are used for fundamental ...

s confirmed the SU(3) model.

History and research

Properties and behavior

List

See also

References