Baryons are the family of subatomic particles with a baryon number of 1. A subatomic particle is an elementary or composite Particle smaller than an Atom. The term baryon is usually used to refer to triquarks — baryons made of three quarks. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. "Exotic" baryons made of four quarks and one anti-quark, are known as the pentaquarks, but their existence is not generally accepted. A pentaquark is an hypothetical subatomic particle consisting of a group of five Quarks (compared to three quarks in normal Baryons and two in Mesons, or Each baryon has a corresponding antiparticle (anti-baryon) where quarks are replaced by their corresponding antiquarks and their corresponding anti-quarks replaced by quarks. Amongst the baryons are the protons and neutrons, which make up atomic nuclei, but many other unstable baryons exist as well. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom The term "baryon" is derived from the Greek βαρύς (barys), meaning "heavy," because at the time of their naming it was believed that baryons were characterized by having greater mass than other particles. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly
Baryons are a subset of the hadrons (which are the particles made of quarks) and participate in the strong interaction. In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and
Contents |
Background
Baryons are strongly interacting fermions — that is, they experience the strong nuclear force and are described by Fermi-Dirac statistics, which apply to all particles obeying the Pauli exclusion principle. In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and In Statistical mechanics, Fermi-Dirac statistics is a particular case of Particle statistics developed by Enrico Fermi and Paul Dirac that The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925 This is in contrast to the bosons, which do not obey the exclusion principle. In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein
Baryons, along with mesons, are hadrons, meaning they are particles composed of quarks. In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. Quarks have baryon numbers of B = 1⁄3 and antiquarks have baryon number of B = −1⁄3. The term "baryon" usually refer to triquarks—baryons mades of three quarks (B = 1⁄3 + 1⁄3 + 1⁄3 = 1), but there are other "exotic" baryons, such as pentaquarks — baryons made of four quarks and one antiquark (B = 1⁄3 + 1⁄3 + 1⁄3 + 1⁄3 − 1⁄3 = 1), but their existence is not generally accepted. Theorically, heptaquarks (5 quarks, 2 antiquarks), nonaquarks (6 quarks, 3 antiquarks), etc. could also exist.
Classification
Baryons are classified into groups according to their isospin values and quark content. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. There are six groups of triquarks — nucleon (N), Delta (Δ), Lambda (Λ), Sigma (Σ), Xi (Ξ), and Omega (Ω). In Physics a nucleon is a collective name for two Baryons the Neutron and the Proton. The Delta baryons are relatively light ( Baryons made of only up (u and down (d Quarks of Isospin 3/2 and spin 3/2 whose ground state parity In Particle physics, Lambda (Λ baryons are Baryons containing an Up quark, a Down quark, and a third quark either a Strange quark See also Delta baryon Hyperon Lambda baryon List of mesons List of In Particle physics, (Xi is a name given to a range of Baryons with one up or down Quark and two heavier quarks Omega (Ω baryons are Baryons containing neither up nor down quarks of Isospin I&thinsp=&thinsp0 The rules for classification are defined by the Particle Data Group. The Particle Data Group is an international collaboration of particle Physicists that compiles and reanalyzes published results related to the properties of particles These rules consider the u, d and s quarks to be light and the c, b, and t to be heavy. The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. The strange quark is a second- generation Quark with a charge of &minus(1/3 e and a strangeness of &minus1 The charm Quark is a second-generation quark with an electric charge of +(2/3 e. The bottom quark is a third-generation Quark with a charge of − e. The top quark is the third- generation up-type Quark with a charge of +(2/3 e. The rules cover all the particles that can be made from three of each of the six quarks (up, down, strange, charm, bottom, top) — even though baryons made of top quarks are not expected to exist because of the top quark's short lifetime—but not pentaquarks. The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. The strange quark is a second- generation Quark with a charge of &minus(1/3 e and a strangeness of &minus1 The charm Quark is a second-generation quark with an electric charge of +(2/3 e. The bottom quark is a third-generation Quark with a charge of − e. The top quark is the third- generation up-type Quark with a charge of +(2/3 e. [1]:
- Baryons with three u and/or d quarks are N's (isospin 1⁄2) or Δ's (isospin 3⁄2). The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. In Physics a nucleon is a collective name for two Baryons the Neutron and the Proton. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the The Delta baryons are relatively light ( Baryons made of only up (u and down (d Quarks of Isospin 3/2 and spin 3/2 whose ground state parity
- Baryons with two u and/or d quarks are Λ's (isospin 0) or Σ's (isospin 1). The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. In Particle physics, Lambda (Λ baryons are Baryons containing an Up quark, a Down quark, and a third quark either a Strange quark See also Delta baryon Hyperon Lambda baryon List of mesons List of If the third quark is heavy, its identity is given by a subscript.
- Baryons with one u or d quark are Ξ's (isospin 1⁄2). The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. In Particle physics, (Xi is a name given to a range of Baryons with one up or down Quark and two heavier quarks One or two subscripts are used if one or both of the remaining quarks are heavy.
- Baryons with no u or d quarks are Ω's (isospin 0), and subscripts indicate any heavy quark content. The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. Omega (Ω baryons are Baryons containing neither up nor down quarks of Isospin I&thinsp=&thinsp0
- Baryons that decay strongly have their masses as part of their names. For example, Sigmas (Σ) and Omegas (Ω) do not decay strongly, but Deltas (Δ(1232)), and charmed Xis (Ξ+c(2645)) do.
Quarks carry charge, so knowing the charge of a particle indirectly gives the quark content. For example, the rules above say that the Σb contains a bottom and some combination of two up and/or down quarks. A Σ0b must be one up quark (Q=2⁄3), one down quark (Q=−1⁄3), and one bottom quark (Q=−1⁄3) to have the correct charge (Q=0).
The number of baryons within one group (excluding resonances) is given by the number of isospin projections possible (2 × isospin + 1). For example there are four Δ's, corresponding to the four isospin projections of the isospin value I = 3⁄2: Δ++ (Iz = 3⁄2), Δ+(Iz = 1⁄2), Δ0(Iz = −1⁄2), and Δ−(Iz = −3⁄2). Another example would be the three Σb's, corresponding to the three isospin projections of the isospin value I = 1: Σ+b (Iz = 1), Σ0b(Iz = 0), and Σ−b(Iz = −1).
Baryonic matter
Baryonic matter is matter composed mostly of baryons (by mass), which includes atoms of any sort (and thus includes nearly all matter that we may encounter or experience in everyday life, including our bodies). Matter is commonly defined as being anything that has mass and that takes up space. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Experience as a general concept comprises Knowledge of or skill in or Observation of some thing or some event gained through involvement in or Non-baryonic matter, as implied by the name, is any sort of matter that is not primarily composed of baryons. This might include such ordinary matter as neutrinos or free electrons; however, it may also include exotic species of non-baryonic dark matter, such as supersymmetric particles, axions or black holes. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics and cosmology, dark matter is hypothetical Matter that does not interact with the electromagnetic force but whose presence can be inferred from In Particle physics, supersymmetry (often abbreviated SUSY) is a Symmetry that relates elementary particles of one spin to another particle that The axion is a hypothetical Elementary particle postulated by Peccei-Quinn theory in 1977 to resolve the Strong-CP problem in Quantum chromodynamics A black hole is a theoretical region of space in which the Gravitational field is so powerful that nothing not even Electromagnetic radiation (e The distinction between baryonic and non-baryonic matter is important in cosmology, because Big Bang nucleosynthesis models set tight constraints on the amount of baryonic matter present in the early universe. Physical cosmology, as a branch of Astronomy, is the study of the large-scale structure of the Universe and is concerned with fundamental questions about its In Physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than those of H-1 (i The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy
The very existence of baryons is also a significant issue in cosmology because we have assumed that the Big Bang produced a state with equal amounts of baryons and anti-baryons. The process by which baryons come to outnumber their antiparticles is called baryogenesis (in contrast to a process by which leptons account for the predominance of matter over antimatter, leptogenesis). In Physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between Baryons and anti-baryons in Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their In the strict sense leptogenesis is a process which creates Leptons Theories of leptogenesis try to explain how the Universe changed from a state with no leptons just after
Baryogenesis
Experiments are consistent with the number of quarks in the universe being a constant and, more specifically, the number of baryons being a constant; in technical language, the total baryon number appears to be conserved. In Particle physics, the baryon number is an approximate conserved Quantum number of a system In Physics, a conservation law states that a particular measurable property of an isolated Physical system does not change as the system evolves Within the prevailing Standard Model of particle physics, the number of baryons may change in multiples of three due to the action of sphalerons, although this is rare and has not been observed experimentally. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles A sphaleron (σφαλερός ά όν weak or dangerous is a static (time independent solution to the electroweak field equations of the Standard Model of Particle Some grand unified theories of particle physics also predict that a single proton can decay, changing the baryon number by one; however, this has not yet been observed experimentally. Grand Unification, grand unified theory, or GUT refers to any of several very similar unified field theories or models in Physics that The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The excess of baryons over antibaryons in the present universe is thought to be due to non-conservation of baryon number in the very early universe, though this is not well understood. In Physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between Baryons and anti-baryons in
See also
Notes
- ^ W. This list is of all known and predicted baryons See List of particles for a more detailed list of particles found in Particle physics. In Particle physics, the baryon number is an approximate conserved Quantum number of a system Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them A pentaquark is an hypothetical subatomic particle consisting of a group of five Quarks (compared to three quarks in normal Baryons and two in Mesons, or This is a list of the different types of particles known and hypothesized In Particle physics, proton decay is a hypothetical form of Radioactive decay in which the Proton decays into lighter Subatomic particles -M. Yao et al. (2006). "Naming scheme for hadrons". Journal of Physics G 33 (1). Particle Data Group.
References and further reading
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic