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Encyclopedia > Quark
The six flavors of quarks and their most likely decay modes. Mass decreases moving from right to left.

A quark (IPA: /kwɔrk/, IPA: /kwɑːk/ or IPA: /kwɑːrk/[1]) is a generic type of physical particle that forms one of the two basic constituents of matter, the other being the lepton. Various species of quarks combine in specific ways to form protons and neutrons, in each case taking exactly three quarks to make the composite particle in question. A quark is a subatomic particle. ... Image File history File links Quarks_and_decays. ... Image File history File links Quarks_and_decays. ... Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... This article is about matter in physics and chemistry. ... For the former Greek currency unit, see Greek drachma. ... For alternative meanings see proton (disambiguation). ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/c² (1. ...


There are six different types of quark, usually known as flavors: up, down, charm, strange, top, and bottom. (Their names do not indicate anything about their properties, but were chosen arbitrarily based on the need to name them something that could be easily remembered and used.) The charm, strange, top, and bottom varieties are highly unstable, and are believed to have decayed within a fraction of a second after the Big Bang – though they can be briefly recreated and studied by scientists. However, the "up" and "down" varieties are abundant and are distinguished by (amongst other things) their electric charge. It is this which makes the difference when quarks clump together to form protons or neutrons: a proton is made up of two "up quarks" and one "down quark", yielding a net charge of +1, while a neutron contains one "up quark" and two "down quarks", yielding a net charge of 0. Flavour (or flavor) is a quantum number of elementary particles related to their weak interactions. ... The up quark is a first-generation quark with a charge of +(2/3)e. ... The down quark is a first-generation quark with a charge of -(1/3)e. ... The charm quark is a second-generation quark with a charge of +(2/3)e. ... The strange quark is a second-generation quark with a charge of -(1/3)e and a strangeness of −1. ... The top quark is the third-generation up-type quark with a charge of +(2/3)e. ... The bottom quark is a third-generation quark with a charge of -(1/3)e. ... For other uses, see Big Bang (disambiguation). ...


In nature, quarks are always found bound together in groups like this, and never in isolation, because of a phenomenon known as confinement. These groups of quarks are called hadrons, with groups of two quarks known specifically as mesons and groups of three quarks as baryons. Colour confinement (often just confinement) is the physics phenomenon that color charged particles (such as quarks) cannot be isolated. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called Greek barys, meaning heavy, as they are heavier than the other main groups of particles. ...


Quarks are the only fundamental particles that interact through all four of the fundamental forces. Antiparticles of quarks are called antiquarks. ... A fundamental interaction or fundamental force is a mechanism by which particles interact with each other, and which cannot be explained in terms of another interaction. ... Corresponding to most kinds of particle, there is an associated antiparticle with the same mass and opposite charges. ...

Contents

Properties

The following table summarizes the key properties of the six known quarks:

Generation Weak
Isospin
Flavor Name Symbol Charge
e
Mass
MeV/c2
Antiparticle Antiparticle
Symbol
1 Iz=+½ Up u +⅔ 1.5 – 4.0 Antiup u
1 Iz=-½ Down d -⅓ 4 – 8 Antidown d
2 C=1 Charm c +⅔ 1150 – 1350 Anticharm c
2 S=-1 Strange s -⅓ 80 – 130 Antistrange s
3 T=1 Top t +⅔ 170900 ± 1800[2] Antitop t
3 B'=-1 Bottom b -⅓ 4100 – 4400 Antibottom b
  • Top quark mass from the Tevatron Electroweak Working Group
  • Other quark masses from Particle Data Group; these masses are given in the MS-bar scheme.
  • The quantum numbers of the top and bottom quarks are sometimes known as truth and beauty respectively, as an alternative to topness and bottomness.

The elementary charge (symbol e or sometimes q) is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... Albert Einsteins equation E=mc² is among the best-known equations of all time. ... The up quark is a first-generation quark with a charge of +(2/3)e. ... The down quark is a first-generation quark with a charge of -(1/3)e. ... The charm quark is a second-generation quark with a charge of +(2/3)e. ... The strange quark is a second-generation quark with a charge of -(1/3)e and a strangeness of −1. ... The top quark is the third-generation up-type quark with a charge of +(2/3)e. ... The bottom quark is a third-generation quark with a charge of -(1/3)e. ... In quantum field theory, the minimal subtraction scheme, or MS scheme is a particular renormalization scheme used to absorb the infinities that arise in perturbative calculations beyond leading order. ...

Flavor

Each quark is assigned a baryon number, B  =  1/3, and a vanishing lepton number L  =  0. They have fractional electric charge, Q, either Q  =  +2/3 or Q  =  −1/3. The former are called up-type quarks, the latter, down-type quarks. Each quark is assigned a weak isospin: Tz  =  +1/2 for an up-type quark and Tz  =  −1/2 for a down-type quark. Each doublet of weak isospin defines a generation of quarks. There are three generations, and hence six flavors of quarks — the up-type quark flavors are up, charm and top; the down-type quark flavors are down, strange, and bottom (each list is in the order of increasing mass). In particle physics, the baryon number is an approximate conserved quantum number. ... In high energy physics, the lepton number is the number of leptons minus the number of antileptons. ... This box:      Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... The weak isospin in theoretical physics parallels the idea of the isospin under the strong interaction, but applied under the weak interaction. ... In particle physics, a generation is a division of the elementary particles. ... In particle physics, flavor is a property of a fermion that identifies it, a label that specifies the name of the particle. ...


The number of generations of quarks and leptons are equal in the standard model. The number of generations of leptons with a light neutrino is strongly constrained by experiments at the LEP in CERN and by observations of the abundance of helium in the universe. Precision measurement of the lifetime of the Z boson at LEP constrains the number of light neutrino generations to be three. Astronomical observations of helium abundance give consistent results. Results of direct searches for a fourth generation give limits on the mass of the lightest possible fourth generation quark. The most stringent limit comes from analysis of results from the Tevatron collider at Fermilab, and shows that the mass of a fourth-generation quark must be greater than 190 GeV. Additional limits on extra quark generations come from measurements of quark mixing performed by the experiments Belle and BaBar. The Large Electron-Positron Collider (usually called LEP for short. ... CERN logo The European Organization for Nuclear Research (French: ), commonly known as CERN (see Naming), pronounced (or in French), is the worlds largest particle physics laboratory, situated just northwest of Geneva on the border between France and Switzerland. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... Aerial view of the Fermilab site. ... A GEV (or Ground Effect Vehicle) is vehicle that takes advantage of the aerodynamic principle of ground effect (or Wing-in-ground). ... The Belle Experiment is a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers investigating CP-violation effects at the High Energy Accelerator Research Organisation (KEK) in Tsukuba, Ibaraki Prefecture, Japan. ... The BaBar (B and B-bar) experiment is an international collaboration of more than 550 physicists and engineers investigating CP-violation effects using the BaBar particle detector at the Stanford Linear Accelerator Center, which is operated by Stanford University in California. ...


Each flavor defines a quantum number which is conserved under the strong interactions, but not the weak interactions. The magnitude of flavor changing in the weak interaction is encoded into a structure called the CKM matrix. This also encodes the CP violation allowed in the Standard Model. The flavor quantum numbers are described in detail in the article on flavor. The strong interaction or strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics (QCD). ... The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four fundamental interactions of nature. ... In the standard model of particle physics the Cabibbo Kobayashi Maskawa matrix (CKM matrix, sometimes earlier called KM matrix) is a unitary matrix which contains information on the strength of flavour changing weak decays. ... In particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics. ... In particle physics, flavor is a property of a fermion that identifies it, a label that specifies the name of the particle. ...


Spin

Quantum numbers corresponding to non-Abelian symmetries like rotations require more care in extraction, since they are not additive. In the quark model one builds mesons out of a quark and an antiquark, whereas baryons are built from three quarks. Since mesons are bosons (having integer spins) and baryons are fermions (having half-integer spins), the quark model implies that quarks are fermions. Further, the fact that the lightest baryons have spin-1/2 implies that each quark can have spin S  =  1/2. The spins of excited mesons and baryons are completely consistent with this assignment. In mathematics, an abelian group, also called a commutative group, is a group (G, *) such that a * b = b * a for all a and b in G. Abelian groups are named after Niels Henrik Abel. ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... Combinations of three u, d or s-quarks with a total spin of 3/2 form the so-called baryon decuplet. ... In particle physics, bosons are particles with an integer spin, as opposed to fermions which have half-integer spin. ... In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ...


Color

Main article: Color charge

Since quarks are fermions, the Pauli exclusion principle implies that the three valence quarks must be in an antisymmetric combination in a baryon. However, the charge Q =  2 baryon, Δ++ (which is one of four isospin Iz  =  3/2 baryons) can only be made of three u quarks with parallel spins. Since this configuration is symmetric under interchange of the quarks, it implies that there exists another internal quantum number, which would then make the combination antisymmetric. This is given the name "color", although it has nothing to do with the perception of the frequency (or wavelength) of light, which is the usual meaning of color. This quantum number is the charge involved in the gauge theory called quantum chromodynamics (QCD). In quantum chromodynamics (QCD), color or color charge refers to a certain property of the subatomic particles called quarks. ... The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. ... The Delta baryon is a relatively light 1,232 MeV/c² baryon which contains only up (u) and down (d) quarks in a combination whose total spin is 3/2 and its ground state parity is +. All varieties of Δ quickly decay via the strong force into an ordinary nucleon plus... In quantum chromodynamics (QCD), color or color charge refers to a certain property of the subatomic particles called quarks. ... Color is an important part of the visual arts. ... In physics, gauge theories are a class of physical theories based on the idea that symmetry transformations can be performed locally as well as globally. ... Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ...


The only other colored particle is the gluon, which is the gauge boson of QCD. Like all other non-Abelian gauge theories (and unlike quantum electrodynamics) the gauge bosons interact with one another by the same force that affects the quarks. In particle physics, gluons are subatomic particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. ... Quantum electrodynamics (QED) is a relativistic quantum field theory of electrodynamics. ...


Color is a gauged SU(3) symmetry. Quarks are placed in the fundamental representation, 3, and hence come in three colors (red, green, and blue). Gluons are placed in the adjoint representation, 8, and hence come in eight varieties. In mathematics, the special unitary group of degree n is the group of n by n unitary matrices with determinant 1 and entries from the field C of complex numbers, with the group operation that of matrix multiplication. ... In mathematics, a fundamental representation is a representation of a mathematical structure, such as a group, that satisfies the following condition: All other irreducible representations of the group can be found in the tensor products of the fundamental representation with many copies of itself. ... In mathematics, the adjoint representation (or adjoint action) of a Lie group G is the natural representation of G on its own Lie algebra. ...


Confinement and quark properties

Main article: Color confinement

Every subatomic particle is completely described by a small set of observables such as mass m and quantum numbers, such as spin b and parity r. Usually these properties are directly determined by experiments. However, confinement makes it impossible to measure these properties of quarks. Instead, they must be inferred from measurable properties of the composite particles which are made up of quarks. Such inferences are usually most easily made for certain additive quantum numbers called flavors. Colour confinement (often just confinement) is the physics phenomenon that color charged particles (such as quarks) cannot be isolated. ... Helium atom (schematic) Showing two protons (red), two neutrons (green) and two electrons (yellow). ... The term mass in special relativity is used in a couple of different ways, occasionally leading to a great deal of confusion. ... Quantum numbers describe values of conserved quantity in the dynamics of the quantum system. ... In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ... In physics, a parity transformation (also called parity inversion) is the simultaneous flip in the sign of all spatial coordinates: A 3×3 matrix representation of P would have determinant equal to –1, and hence cannot reduce to a rotation. ... In particle physics, flavor is a property of a fermion that identifies it, a label that specifies the name of the particle. ...


The composite particles made of quarks and antiquarks are the hadrons. These include the mesons which get their quantum numbers from a quark and an antiquark, and the baryons, which get theirs from three quarks. The quarks (and antiquarks) which impart quantum numbers to hadrons are called valence quarks. Apart from these, any hadron may contain an indefinite number of virtual quarks, antiquarks and gluons which together contribute nothing to their quantum numbers. Such virtual quarks are called sea quarks. A hadron, in particle physics, is a subatomic particle which experiences the nuclear force. ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... Combinations of three u, d or s-quarks with a total spin of 3/2 form the so-called baryon decuplet. ... In physics, a virtual particle is a particle which exists for such a short time and space that its energy and momentum do not have to obey the usual relationship. ... In particle physics, gluons are subatomic particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. ...


It is now believed that so-called "neutron stars", collapsed remnants of a massive star in which the protons and electrons degenerate and combine to form neutrons, might actually exist instead in the form of up, down and strange quarks as a single "atom" in what is called a quark star. This article is about the celestial body. ... A strange star or quark star is a hypothetical type of star composed of strange matter, or quark matter. ...


Free quarks

1974 discovery photograph of a possible charmed baryon, now identified as the Σ++c
1974 discovery photograph of a possible charmed baryon, now identified as the Σ++c

No search for free quarks or fractional electric charges has returned convincing evidence. The absence of free quarks has therefore been incorporated into the notion of confinement, which, it is believed, the theory of quarks must possess. This was expounded upon by Frank Wilczek, H. David Politzer and David Gross who concluded that the more quarks separated, the greater the attraction due to the strong force, making it impossible to separate the quarks into free particles. This has been called asymptotic freedom, for which Gross, Politzer, and Wilczek was awarded the Nobel Prize in Physics in 2004[3]. Bubble chamber tracks of the decay of a charmed baryon, first published in 1975. ... Bubble chamber tracks of the decay of a charmed baryon, first published in 1975. ... Frank Wilczek (born May 15, 1951) is a Nobel prize winning American physicist. ... Prof. ... David Jonathan Gross (born February 19, 1941 in Washington, D.C.) is an American particle physicist and string theorist (although hes stated to the Brazilian newspaper Folha de São Paulo, on 09/27/2006, that the second area is included in the first one). ... The strong nuclear force or strong interaction (also called color force or colour force) is a fundamental force of nature which affects only quarks and antiquarks, and is mediated by gluons in a similar fashion to how the electromagnetic force is mediated by photons. ... In physics, asymptotic freedom is the property of some gauge theories in which the interaction between the particles, such as quarks, becomes arbitrarily weak at ever shorter distances, i. ...


Confinement began as an experimental observation, and is expected to follow from the modern theory of strong interactions, called quantum chromodynamics (QCD). Although there is no mathematical derivation of confinement in QCD, it is easy to show using lattice gauge theory. The strong interaction or strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics (QCD). ... Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ... In physics, lattice gauge theory is the study of the behaviour of lattice model gauge theories. ...


However, it may be possible to change the confinement by creating dense or hot quark matter. These new phases of QCD matter have been predicted theoretically, and experimental searches for them have now started at the RHIC. Under some theories, sufficient energy input [by high-speed relativistic collisions such as at the RHIC and planned at the LHC might also generate strange quarks arising from the vacuum, which could recombine with the up and down quarks to form a new type of nucleon called a strangelet or strange quark matter. Wilczek cautioned that there might be concern for an "ice-9" type reaction, in which a strangelet engaged in runaway fusion with normal nuclei, in a Letter[4] to the Editor of Scientific American in 1999. However, he concluded that there likely should be no cause for concern, as most theories[5][6] show such strangelets to be positively charged, and would repulse normal nuclei due to the charge repulsion of Coulomb's law. Quark Matter refers to any of a number of phases of matter built out of quarks and gluons. ... Quark matter or QCD matter refers to any of a number of phases of matter whose degrees of freedom include quarks and gluons. ... The Relativistic Heavy Ion Collider (RHIC) is a heavy-ion collider located at and operated by the Brookhaven National Laboratory in Upton, New York. ... For the pop group, see Les Horribles Cernettes Construction of the CMS detector for LHC at CERN The Large Hadron Collider (short LHC) is a particle accelerator and collider located at CERN. It is currently under construction and scheduled to start operation in 2007. ... Look up Vacuum in Wiktionary, the free dictionary. ... A strangelet or strange nugget is a hypothetical object, consisting of a bound state of roughly equal numbers of up, down, and strange quarks. ... Strange matter is an ultra-dense phase of matter that is theorized to form inside particularly massive neutron stars. ... Ice-9 is a fictional material conceived by science fiction writer Kurt Vonnegut in his novel Cats Cradle. ... Scientific American is a popular-science magazine, published (first weekly and later monthly) since August 28, 1845, making it the oldest continuously published magazine in the United States. ... The coulomb (symbol: C) is the SI unit of electric charge. ...


Quark masses

Although one speaks of quark mass in the same way as the mass of any other particle, the notion of mass for quarks is complicated by the fact that quarks cannot be found free in nature. As a result, the notion of a quark mass is a theoretical construct, which makes sense only when one specifies exactly the procedure used to define it.


Current quark mass

The approximate chiral symmetry of quantum chromodynamics, for example, allows one to define the ratio between various (up, down and strange) quark masses through combinations of the masses of the pseudo-scalar meson octet in the quark model through chiral perturbation theory, giving A phenomenon is said to be chiral if it is not identical to its mirror image (see Chirality (mathematics)). The spin of a particle may be used to define a handedness for that particle. ... Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, i. ... Chiral perturbation theory (ChPT) is an effective field theory constructed with a lagrangian consistent with the (approximate) chiral symmetry of quantum chromodynamics (QCD), as well as the other symmetries of parity and charge conjugation. ...

frac{m_u}{m_d}=0.56qquad{rm and}qquadfrac{m_s}{m_d}=20.1.

The fact that the up quark has mass is important, since there would be no strong CP problem if it were massless. The absolute values of the masses are currently determined from QCD sum rules (also called spectral function sum rules) and lattice QCD. Masses determined in this manner are called current quark masses. The connection between different definitions of the current quark masses needs the full machinery of renormalization for its specification. In particle physics, the strong CP problem is the puzzling question why Quantum Chromodynamics (QCD) does not seem to break the CP-symmetry. ... It has been suggested that lattice field theory be merged into this article or section. ... Figure 1. ...


Valence quark mass

Another, older, method of specifying the quark masses was to use the Gell-Mann-Nishijima mass formula in the quark model, which connect hadron masses to quark masses. The masses so determined are called constituent quark masses, and are significantly different from the current quark masses defined above. The constituent masses do not have any further dynamical meaning. In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, i. ... A hadron, in particle physics, is a subatomic particle which experiences the nuclear force. ...


Heavy quark masses

The masses of the heavy charm and bottom quarks are obtained from the masses of hadrons containing a single heavy quark (and one light antiquark or two light quarks) and from the analysis of quarkonia. Lattice QCD computations using the heavy quark effective theory (HQET) or non-relativistic quantum chromodynamics (NRQCD) are currently used to determine these quark masses. In high energy physics, a quarkonium (pl. ... It has been suggested that lattice field theory be merged into this article or section. ...


The top quark is sufficiently heavy that perturbative QCD can be used to determine its mass. Before its discovery in 1995, the best theoretical estimates of the top quark mass are obtained from global analysis of precision tests of the Standard Model. The top quark, however, is unique amongst quarks in that it decays before having a chance to hadronize. Thus, its mass can be directly measured from the resulting decay products. This can only be done at the Tevatron which is the only particle accelerator energetic enough to produce top quarks in abundance. Perturbative QCD is the study of the theory of Quantum chromodynamics in energy regimes where the strong coupling constant is small, allowing Perturbation theory to be applied. ... The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... Atom Smasher redirects here. ...


Antiquarks

The additive quantum numbers of antiquarks are equal in magnitude and opposite in sign to those of the quarks. CPT symmetry forces them to have the same spin and mass as the corresponding quark. Tests of CPT symmetry cannot be performed directly on quarks and antiquarks, due to confinement, but can be performed on hadrons. Notation of antiquarks follows that of antimatter in general: an up quark is denoted by u, and an up antiquark is denoted by u. CPT-symmetry is a fundamental symmetry of physical laws under transformations that involve the inversions of charge, parity and time simultaneously. ...


Substructure

Some extensions of the Standard Model begin with the assumption that quarks and leptons have substructure. In other words, these models assume that the elementary particles of the Standard Model are in fact composite particles, made of some other elementary constituents. Such an assumption is open to experimental tests, and these theories are severely constrained by data. At present there is no evidence for such substructure. For more details see the article on preons. The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ... For the former Greek currency unit, see Greek drachma. ... In particle physics, preons are postulated point-like particles, conceived to be subcomponents of quarks and leptons. ...


History

The notion of quarks evolved out of a classification of hadrons developed independently in 1961 by Murray Gell-Mann and Kazuhiko Nishijima, which nowadays goes by the name of the quark model. The scheme grouped together particles with isospin and strangeness using a unitary symmetry derived from current algebra, which we today recognize as part of the approximate chiral symmetry of QCD. This is a global flavor SU(3) symmetry, which should not be confused with the gauge symmetry of QCD. A hadron, in particle physics, is a subatomic particle which experiences the nuclear force. ... Murray Gell-Mann (born September 15, 1929 in Manhattan, New York City, USA) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, i. ... This does not cite its references or sources. ... In mathematics, the special unitary group of degree n is the group of n by n unitary matrices with determinant 1 and entries from the field C of complex numbers, with the group operation that of matrix multiplication. ...


In this scheme the lightest mesons (spin-0) and baryons (spin-½) are grouped together into octets, 8, of flavor symmetry. A classification of the spin-3/2 baryons into the representation 10 yielded a prediction of a new particle, Ω, the discovery of which in 1964 led to wide acceptance of the model. The missing representation 3 was identified with quarks. Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ...


This scheme was called the eightfold way by Gell-Mann, a clever conflation of the octets of the model with the eightfold way of Buddhism. He also chose the name quark and attributed it to the sentence “Three quarks for Muster Mark” in James Joyce's Finnegans Wake.[7] In reply to the common claim that he did not actually believe that quarks were real physical entities, Gell-Mann has been quoted as saying - "That is baloney. I have explained so many times that I believed from the beginning that quarks were confined inside objects like neutrons and protons, and in my early papers on quarks I described how they could be confined either by an infinite mass and infinite binding energy, or by a potential rising to infinity, which is what we believe today to be correct. Unfortunately, I referred to confined quarks as 'fictitious', meaning that they could not emerge to be utilized for applications such as catalysing nuclear fusion."[8] It has been suggested that this article or section be merged into quark model. ... Eightfold Path redirects here. ... Buddhism, a Dharmic faith, is usually considered one of the worlds major religions, with between 230 to 500 million followers. ... This article is about the writer and poet. ... For the street ballad which the novel is named after, see Finnegans Wake. ...


Analysis of certain properties of high energy reactions of hadrons led Richard Feynman to postulate substructures of hadrons, which he called partons (since they form part of hadrons). A scaling of deep inelastic scattering cross sections derived from current algebra by James Bjorken received an explanation in terms of partons. When Bjorken scaling was verified in an experiment in 1969, it was immediately realized that partons and quarks could be the same thing. With the proof of asymptotic freedom in QCD in 1973 by David Gross, Frank Wilczek and David Politzer the connection was firmly established. This article is about the physicist. ... In particle physics, the parton was a hypothetical fundamental particle considered, in the parton model of strong interactions, to be a constituent of the hadron. ... Deep Inelastic Scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons. ... James Bjorken James Daniel BJ Bjorken is an American theoretical physicist. ... James Bjorken James Daniel BJ Bjorken is an American theoretical physicist. ... In physics, asymptotic freedom is the property of some gauge theories in which the interaction between the particles, such as quarks, becomes arbitrarily weak at ever shorter distances, i. ... David Jonathan Gross (born February 19, 1941 in Washington, D.C.) is an American particle physicist and string theorist (although hes stated to the Brazilian newspaper Folha de São Paulo, on 09/27/2006, that the second area is included in the first one). ... Frank Wilczek (born May 15, 1951) is a Nobel prize winning American physicist. ... Hugh David Politzer (born 31 August 1949) is an American theoretical physicist. ...


The charm quark was postulated by Sheldon Glashow, John Iliopoulos and Luciano Maiani in 1970 to prevent unphysical flavor changes in weak decays which would otherwise occur in the standard model. The discovery in 1974 of the meson which came to be called the J/ψ led to the recognition that it was made of a charm quark and its antiquark. Professor Sheldon Lee Glashow (born December 5, 1932) is an American physicist. ... John Iliopoulos, a Greek physicist born in 1940, was the first person to present the Standard Model of particle physics in a single report. ... Luciano Maiani is an Italian physicist best known for his prediction of the charm quark with Glashow and Iliopoulos. ... The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... Spark-chamber trace of a ψ to J/ψ decay at SLAC The J/ψ is an elementary particle, namely a flavor-neutral meson consisting of a charm quark and a charm anti-quark. ...


The existence of a third generation of quarks was predicted by Makoto Kobayashi and Toshihide Maskawa in 1973 who realized that the observed violation of CP symmetry by neutral kaons could not be accommodated into the Standard Model with two generations of quarks. The bottom quark was discovered in 1977 and the top quark in 1996 at the Tevatron collider in Fermilab. Makoto Kobayashi (小林誠) is a Japanese physicist well-known for his work on CP-violation. ... Toshihide Maskawa is a Japanese physicist well-known for his work on CP-violation. ... CP is the product of two symmetries: C for charge conjugation, which transforms a particle into its antiparticle, and P for parity, which creates the mirror image of a physical system. ... In particle physics, Kaons (also called K-mesons and denoted K) are a group of four mesons distinguished by the fact that they carry a quantum number called strangeness. ... The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... Aerial view of the Fermilab site. ...


Origin of the word

The word was originally coined by Murray Gell-Mann as a nonsense word rhyming with "pork"[9], but without a spelling. Later, he found the word "quark" in James Joyce's book Finnegans Wake, and used the spelling but not the pronunciation: Murray Gell-Mann (born September 15, 1929 in Manhattan, New York City, USA) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. ... This article is about the writer and poet. ... For the street ballad which the novel is named after, see Finnegans Wake. ...

Three quarks for Muster Mark!
Sure he has not got much of a bark
And sure any he has it's all beside the mark.

In this context, the word rhymes with "mark", and "bark", but the physics term is pronounced "kwork". Gell-Mann's own explanation:[10][11]


The pronunciation is also justified by the fact that in most regional accents of American English, the combinations "uar" and "war" are almost always pronounced "wor."

In 1963, when I assigned the name "quark" to the fundamental constituents of the nucleon, I had the sound first, without the spelling, which could have been "kwork". Then, in one of my occasional perusals of Finnegans Wake, by James Joyce, I came across the word "quark" in the phrase "Three quarks for Muster Mark". Since "quark" (meaning, for one thing, the cry of the gull) was clearly intended to rhyme with "Mark," as well as "bark" and other such words, I had to find an excuse to pronounce it as "kwork". But the book represents the dream of a publican named Humphrey Chimpden Earwicker. Words in the text are typically drawn from several sources at once, like the "portmanteau" words in "Through the Looking Glass". From time to time, phrases occur in the book that are partially determined by calls for drinks at the bar. I argued, therefore, that perhaps one of the multiple sources of the cry "Three quarks for Muster Mark" might be "Three quarts for Mister Mark," in which case the pronunciation "kwork" would not be totally unjustified. In any case, the number three fitted perfectly the way quarks occur in nature.

The phrase "three quarks" is a particularly good fit (as mentioned in the above quote), as at the time, there were only three known quarks, and since quarks appear in groups of three in baryons.


In Joyce's use, it is seabirds giving "three quarks", akin to three cheers, "quark" having a meaning of the cry of a gull (probably onomatopoeia, like "quack" for ducks). The word is also a pun on the relationship between Munster and its provincial capital, Cork.[citation needed] For the supervillain, see Onomatopoeia (comics). ... Statistics Area: 24,607. ... This article is about the city in the Republic of Ireland. ...


See also

A fundamental interaction is a mechanism by which particles interact with each other, and which cannot be explained by another more fundamental interaction. ... The strong interaction or strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics (QCD). ... In particle physics, gluons are subatomic particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. ... Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ... In particle physics, the parton was a hypothetical fundamental particle considered, in the parton model of strong interactions, to be a constituent of the hadron. ... Colour confinement (often just confinement) is the physics phenomenon that color charged particles (such as quarks) cannot be isolated. ... Deconfinement in Quantum Chromodynamics refers to a phase of matter in which quarks and gluons are free to move over distances larger than a femtometer (which is the size of a hadron). ... Quark Matter refers to any of a number of phases of matter built out of quarks and gluons. ... In physics, asymptotic freedom is the property of some gauge theories in which the interaction between the particles, such as quarks, becomes arbitrarily weak at ever shorter distances, i. ... The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ... This is a detailed description of the standard model (SM) of particle physics. ... In the standard model of particle physics the Cabibbo Kobayashi Maskawa matrix (CKM matrix, sometimes earlier called KM matrix) is a unitary matrix which contains information on the strength of flavour changing weak decays. ... CP is the product of two symmetries: C for charge conjugation, which transforms a particle into its antiparticle, and P for parity, which creates the mirror image of a physical system. ... A strange star or quark star is a hypothetical type of star composed of strange matter, or quark matter. ...

References and external links

  1. ^ http://www.merriam-webster.com/dictionary/quark and Oxford University Press, 2005
  2. ^ Summary of Top Mass Results - March 2007.
  3. ^ Nobel Prize in Physics 2004. Nobel Foundation. Retrieved on 26 May 2008
  4. ^ Scientific American, July, 1999
  5. ^ However, even that is not certain if the enchanced stability of the strangelet causes spontaneous fusion. Further, other theories show neutral or negative strangelets where this would not be a barrier. >"Search for Neutral Strangelets at the E864 experiment"; Marcelo Munhoz (Wayne State University) ABSTRACT: The E864 experiment is a large acceptance forward spectrometer designed to search for exotic composite objects potentially produced in relativistic Au+Pb collisions at the Brookhaven AGS. Among these objects are the strangelets, hadrons composed of approximately equal numbers of u, d, and s quarks, and, consequently, characterized by low charge to mass ratios. Its existence cannot be resolved through theorethical predictions, so the solution relies on experimental measurements. This work represents the first attempt to look for neutral strangelets, made possible due to the excellent performance of the E864 hadronic calorimeter. No neutral strangelets were observed in the 1995 run data set, but we set production limits for these exotic objects, in the mass range 6<A<100. The limit is rather insensitive to the details of production models thanks to the large acceptance of the E864 spectrometer. "Properties of exotic matter for heavy-ion searches" J Schaffner-Bielich et al 1997 J. Phys. G: Nucl. Part. Phys. 23 2107-2115 doi:10.1088/0954-3899/23/12/036; J Schaffner-Bielich, C Greiner, H Stöcker§ and A P Vischer; Nuclear Science Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA; Institut für Theoretische Physik, Justus-Liebig Universität, D-35392 Giessen, Germany; Institut für Theoretische Physik, J W Goethe-Universität, D-60054 Frankfurt, Germany; Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen, Denmark; ABSTRACT: We examine the properties of both forms of strange matter, small lumps of strange quark matter (strangelets) and of strange hadronic matter (metastable exotic multihypernuclear objects (MEMOs)) and their relevance for present and future heavy-ion searches. The strong and weak decays are discussed separately to distinguish between long- and short-lived candidates where the former ones are detectable in present heavy-ion experiments while the latter ones are present in future heavy-ion experiments, respectively. We find some long-lived strangelet candidates which are highly negatively charged with a mass-to-charge ratio like a anti deuteron but masses of A = 10 - 16. We also predict many short-lived candidates, both in quark and hadronic form, which can be highly charged. Purely hyperonic nuclei such as the are bound and have a negative charge while carrying a positive baryon number. We also demonstrate that multiply charmed exotics (charmlets) might be bound and can be produced at future heavy-ion colliders. Print publication: Issue 12 (December 1997)
  6. ^ "New Solutions for the Color-Flavored Locked Strangelets"; G.X. Peng, X.J.Wen, and Y.D. Chen, of the China Center of Advanced Science (World Lab.) [Beijing], the Institute of High Energy Physics, Chinese Academy of Sciences [Beijing], and the Center for Theoretical Physics MIT [Cambridge], respectively; December 9, 2005
  7. ^ quark 1. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000
  8. ^ Rodgers 2003.
  9. ^ Gribbin, John. "Richard Feynman: A Life in Science" Dutton 1997, pg 194.
  10. ^ Gell-Mann, Murray (1995). The Quark and the Jaguar. Owl Books, 180. ISBN 978-0805072532. 
  11. ^ Take Our Word For It, page two, Words to the Wise

The Nobel Foundation was created by Lord Alfred Nobel, the inventor of dynamite, to manage his estate and award prizes for academic achievement in several areas: physics, chemistry, medicine, literature, and peace. ... is the 146th day of the year (147th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance with the Gregorian calendar. ... Murray Gell-Mann (born September 15, 1929 in Manhattan, New York City, USA) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. ...

Primary and secondary sources

David J. Griffiths is a U.S. physicist and educator. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 304th day of the year (305th in leap years) in the Gregorian calendar. ...

Other references

Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... For the novel, see The Elementary Particles. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... The up quark is a first-generation quark with a charge of +(2/3)e. ... The down quark is a first-generation quark with a charge of -(1/3)e. ... The charm quark is a second-generation quark with a charge of +(2/3)e. ... The strange quark is a second-generation quark with a charge of -(1/3)e and a strangeness of −1. ... The top quark is the third-generation up-type quark with a charge of +(2/3)e. ... The bottom quark is a third-generation quark with a charge of -(1/3)e. ... For the former Greek currency unit, see Greek drachma. ... For other uses, see Electron (disambiguation). ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... The muon (from the letter mu (μ)--used to represent it) is an elementary particle with negative electric charge and a spin of 1/2. ... The tau lepton (often called the tau, tau particle, or occasionally the tauon, symbol ) is a negatively charged elementary particle with a lifetime of 2. ... For other uses, see Neutrino (disambiguation). ... Antineutrinos, the antiparticles of neutrinos, are neutral particles produced in nuclear beta decay. ... In particle physics, bosons are particles with an integer spin, as opposed to fermions which have half-integer spin. ... Gauge bosons are bosonic particles which act as carriers of the fundamental forces of Nature. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... In particle physics, gluons are subatomic particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. ... In physics, the W and Z bosons, colloquially known as Weakons, are the elementary particles that mediate the weak force. ... In physics, Faddeev-Popov ghost ci is a field that violates the spin-statistics relation. ... In physics, a bound state is a composite of two or more building blocks (particles or bodies) that behaves as a single object. ... A hadron, in particle physics, is a subatomic particle which experiences the nuclear force. ... Combinations of three u, d or s-quarks with a total spin of 3/2 form the so-called baryon decuplet. ... In particle physics, a hyperon is any subatomic particle which is a baryon (and hence a hadron and a fermion) with non-zero strangeness, but with zero charm and zero bottomness. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... For other uses, see Proton (disambiguation). ... This article or section does not adequately cite its references or sources. ... The Delta baryon is a relatively light 1,232 MeV/c² baryon which contains only up (u) and down (d) quarks in a combination whose total spin is 3/2 and its ground state parity is +. All varieties of Δ quickly decay via the strong force into an ordinary nucleon plus... Properties In particle physics, the omega minus (Ω−) is a type of baryon (more specifically, a hyperon). ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... In high energy physics, a quarkonium (pl. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: Ï€0, Ï€+ and π−. Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force. ... In particle physics, Kaons (also called K-mesons and denoted K) are a group of four mesons distinguished by the fact that they carry a quantum number called strangeness. ... In particle physics, a rho meson is a short-lived hadronic particle that is an isospin triplet whose three states are denoted as , and . ... The upsilon particle () is a flavorless meson formed from a bottom quark and its antiparticle. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... For other uses, see Atom (disambiguation). ... An exotic atom is the anologue of a normal atom in which one or more of the electrons are replaced by other negative particles, such as a muon or a pion, or the positively charged nucleus is replaced by other positively charged elementary particles, or both. ... Positronium (Ps) is a system consisting of an electron and its anti-particle, a positron, bound together into an exotic atom. The orbit of the two particles and the set of energy levels is similar to that of the hydrogen atom (electron and proton). ... A muonium particle is an exotic atom made up of a positive muon and an electron, and is given the symbol Mu or μ+e–. During the muons 2 microsecond lifetime, muonium can enter into compounds such as muonium chloride (MuCl) or sodium muonide (NaMu). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... This is a list of particles in particle physics, including currently known and hypothetical elementary particles, as well as the composite particles that can be built up from them. ... In supersymmetry, it is proposed that every fermion should have a partner boson, known as its Superpartner. ... The axino is a hypothetical elementary particle predicted by some theories of particle physics. ... In particle physics, chargino refers to a charged superpartner, i. ... In particle physics, a gaugino is the hypothetical superpartner of a gauge boson, as predicted by gauge theory combined with supersymmetry. ... A gluino is a subatomic particle, the fermion superpartner of the gluon predicted by supersymmetry. ... The gravitino is the hypothetical supersymmetric partner of the graviton, as predicted by theories combining general relativity and supersymmetry, i. ... In particle physics, a higgsino is the hypothetical superpartner of the Higgs boson, as predicted by supersymmetry. ... In particle physics, the neutralino is a hypothetical particle and part of the doubling of the menagerie of particles predicted by supersymmetric theories. ... In particle physics, a sfermion is any of the class of spin-0 superpartners of ordinary fermions appearing in supersymmetric extensions to the Standard Model. ... The axion is an exotic subatomic particle postulated by Peccei-Quinn theory to resolve the strong-CP problem in quantum chromodynamics (QCD). ... In theoretical physics, dilaton originally referred to a theoretical scalar field; as a photon refers in one sense to the electromagnetic field. ... This article is about the hypothetical particle. ... The Higgs boson, also known as the God particle, is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model of particle physics. ... This box:      A tachyon (from the Greek , takhyónion, from , takhýs, i. ... In particle physics, the X and Y bosons are hypothetical elementary particles analogous to the W and Z bosons, but corresponding to a new type of force, such as the forces predicted by grand unified theory. ... It has been suggested that this article or section be merged with Z boson. ... In particle physics, a Z boson (or Z-prime boson) refers to a hypothetical new neutral gauge boson (named in analogy with the Standard Model Z boson). ... A sterile particle does not have any charge known to us. ... A regular meson made from a quark (q) and antiquark (q-bar) with spins s2 and s1 respectively and having an overall angular momentum L Exotic hadrons are subatomic particles made of quarks (and possibly gluons), but which do not fit into the usual schema of hadrons. ... Ordinary baryons are bound states of 3 quarks. ... A pentaquark is a subatomic particle consisting of a group of five quarks (compared to three quarks in normal baryons and two in mesons), or more specifically four quarks and one anti-quark. ... Identities and classification of possible tetraquark mesons. ... In particle physics, a glueball is a particle containing no valence quarks. ... A tetraquark is a subatomic particle composed of four quarks. ... A mesonic molecule is a set of two or more mesons bound together by the strong force. ... In physics, a quasiparticle refers to a particle-like entity arising in certain systems of interacting particles. ... Side view of an α-helix of alanine residues in atomic detail. ... This page is about the quasiparticle. ... There is a place named Magnon (pronunciation: ma-nyon) in Gabon, see Magnon, Gabon A magnon is a collective excitation of the electrons spin structure in a crystal lattice. ... Normal modes of vibration progression through a crystal. ... In physics, the plasmon is the quasiparticle resulting from the quantization of plasma oscillations just as photons and phonons are quantizations of light and sound waves, respectively. ... This article is in need of attention. ... In solid-state physics, a polaron is formed when a moving charge (typically an electron or a hole) in a crystal with some ionic character polarizes (by its electric field) the lattice around it. ... A roton is an excitation in superfluid Helium-4. ... This is a list of particles in particle physics, including currently known and hypothetical elementary particles, as well as the composite particles that can be built up from them. ... Baryon decuplet: Spin=3/2 Baryon octet: Spin=1/2 This is a list of baryons. ... A list of mesons. ... Timeline of subatomic particle discoveries. ...

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