Citizendia

For other uses, see Quark (disambiguation).
The six flavors of quarks and their most likely decay modes. Mass decreases moving from right to left.
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. Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them Matter is commonly defined as being anything that has mass and that takes up space. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their 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. 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.

There are six different types of quark, usually known as flavors: up, down, charm, strange, top, and bottom. In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their 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 charm Quark is a second-generation quark with an electric charge of +(2/3 e. The strange quark is a second- generation Quark with a charge of &minus(1/3 e and a strangeness of &minus1 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 − e. (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. The Big Bang is the cosmological model of the Universe that is best supported by all lines of scientific evidence and Observation. 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.

In nature, quarks are always found bound together in groups like this, and never in isolation, because of a phenomenon known as confinement. Color confinement, often called just confinement, is the Physics phenomenon that Color charged particles (such as Quarks cannot be isolated singularly These groups of quarks are called hadrons, with groups of two quarks known specifically as mesons and groups of three quarks as baryons. In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. Baryons are the family of Subatomic particles with a Baryon number of 1

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

Contents

Properties

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

GenerationWeak
Isospin		FlavorNameSymbolCharge
e		Mass
MeV/c2		AntiparticleAntiparticle
Symbol
1+½Iz=+½Upu+⅔1. The elementary charge, usually denoted e, is the Electric charge carried by a single Proton, or equivalently the negative of the electric charge carried In Physics, mass–energy equivalence is the concept that for particles slower than light any Mass has an associated Energy and vice versa. The up quark is a particle described by the Standard Model theory of Physics. 5 – 4. 0Antiupu
1-½Iz=-½Downd-⅓4 – 8Antidownd
2+½C=1Charmc+⅔1150 – 1350Anticharmc
2-½S=-1Stranges-⅓80 – 130Antistranges
3+½T=1Topt+⅔170900 ± 1800[2]Antitopt
3-½B'=-1Bottomb-⅓4100 – 4400Antibottomb

Flavor

Each quark is assigned a baryon number, B  =  1/3, and a vanishing lepton number L  =  0. In Particle physics, the baryon number is an approximate conserved Quantum number of a system In High energy physics, the lepton number is the number of Leptons minus the number of antileptons They have fractional electric charge, Q, either Q  =  +2/3 or Q  =  −1/3. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. 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. The weak isospin in Particle physics is a quantum number relating to the Weak interaction, and parallels the idea of Isospin under the Strong Each doublet of weak isospin defines a generation of quarks. In Particle physics, a generation is a division of the Elementary particles Between generations particles differ only by their Mass. 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, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their

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. The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical Precision measurement of the lifetime of the Z boson at LEP constrains the number of light neutrino generations to be three. The W and Z bosons are the Elementary particles that mediate the Weak force. 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. Tevatron is a circular Particle accelerator at the Fermi National Accelerator Laboratory in Batavia Illinois and is the highest energy particle collider Fermi National Accelerator Laboratory ( Fermilab) located in Batavia near Chicago, Illinois, is a U Additional limits on extra quark generations come from measurements of quark mixing performed by the experiments Belle and BaBar. The Belle experiment is a Particle physics experiment conducted by the Belle Collaboration an international collaboration of more than 400 physicists and engineers investigating The BaBar experiment is an international collaboration of more than 550 physicists and engineers studying the subatomic world at energy of approximately ten times the rest mass of a proton

Each flavor defines a quantum number which is conserved under the strong interactions, but not the weak interactions. In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature The magnitude of flavor changing in the weak interaction is encoded into a structure called the CKM matrix. In the Standard Model of Particle physics, the Cabibbo-Kobayashi-Maskawa matrix ( CKM matrix, quark mixing matrix, sometimes also called This also encodes the CP violation allowed in the Standard Model. In Particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics The flavor quantum numbers are described in detail in the article on flavor. In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their

Spin

Quantum numbers corresponding to non-Abelian symmetries like rotations require more care in extraction, since they are not additive. Non-abelian may describe Non-abelian group, in mathematics a group that is not abelian (commutative Non-abelian gauge theory, in physics In the quark model one builds mesons out of a quark and an antiquark, whereas baryons are built from three quarks. In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. Baryons are the family of Subatomic particles with a Baryon number of 1 Since mesons are bosons (having integer spins) and baryons are fermions (having half-integer spins), the quark model implies that quarks are fermions. In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. 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.

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. In Particle physics, color charge is a property of Quarks and Gluons which are related to their Strong interactions in the context of Quantum The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925 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. 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 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. In Particle physics, color charge is a property of Quarks and Gluons which are related to their Strong interactions in the context of Quantum This quantum number is the charge involved in the gauge theory called quantum chromodynamics (QCD). Gauge theory is a peculiar Quantum field theory where the Lagrangian is invariant under certain transformations Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the

The only other colored particle is the gluon, which is the gauge boson of QCD. Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the 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. Quantum electrodynamics ( QED) is a relativistic Quantum field theory of Electrodynamics.

Color is a gauged SU(3) symmetry. Special Unit 2In Mathematics, the special unitary group of degree n, denoted SU( n) is the group of n × n Quarks are placed in the fundamental representation, 3, and hence come in three colors (red, green, and blue). In Representation theory of Lie groups and Lie algebras a fundamental representation is an irreducible finite-dimensional representation of a semisimple Gluons are placed in the adjoint representation, 8, and hence come in eight varieties. In Mathematics, the adjoint representation (or adjoint action) of a Lie group G is the natural representation of G on its

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. Color confinement, often called just confinement, is the Physics phenomenon that Color charged particles (such as Quarks cannot be isolated singularly A subatomic particle is an elementary or composite Particle smaller than an Atom. Quantum numbers describe values of conserved numbers in the dynamics of the Quantum system. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Physics, a parity transformation (also called parity inversion) is the flip in the sign of one Spatial Coordinate. 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. In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their

The composite particles made of quarks and antiquarks are the hadrons. In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( These include the mesons which get their quantum numbers from a quark and an antiquark, and the baryons, which get theirs from three quarks. In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. Baryons are the family of Subatomic particles with a Baryon number of 1 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. In Physics, a virtual particle is a particle that exists for a limited time and space introducing uncertainty in their energy and momentum due to the Heisenberg Uncertainty Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the Such virtual quarks are called sea quarks.

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. A neutron star is a type of remnant that can result from the Gravitational collapse of a massive Star during a Type II, Type Ib or Type A quark star or strange star is a hypothetical type of Exotic star composed of Quark matter, or Strange 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. Charmed baryons are a category of Composite particles comprising all Baryons made of at least one Charm quark. 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. Frank Anthony Wilczek (born May 15, 1951) is an American theoretical physicist and Nobel laureate. Hugh David Politzer (born 31 August 1949) is an American theoretical physicist. David Jonathan Gross (born February 19, 1941 in Washington DC In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and This has been called asymptotic freedom, for which Gross, Politzer, and Wilczek was awarded the Nobel Prize in Physics in 2004[3]. In Physics, asymptotic freedom is the property of some gauge theories in which the interaction between the particles such as Quarks, becomes arbitrarily

Confinement began as an experimental observation, and is expected to follow from the modern theory of strong interactions, called quantum chromodynamics (QCD). In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the Although there is no mathematical derivation of confinement in QCD, it is easy to show using lattice gauge theory. In Physics, lattice gauge theory is the study of gauge theories on a spacetime that has been discretized onto a lattice.

However, it may be possible to change the confinement by creating dense or hot quark matter. Quark matter or QCD matter (see QCD) refers to any of a number of theorized phases of matter whose degrees of freedom include Quarks and Gluons These new phases of QCD matter have been predicted theoretically, and experimental searches for them have now started at the RHIC. Quark matter or QCD matter (see QCD) refers to any of a number of theorized phases of matter whose degrees of freedom include Quarks and Gluons The Relativistic Heavy Ion Collider (RHIC pronounced like " Rick " ˈrɪk is a heavy- Ion Collider located at and operated by Brookhaven 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. This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. A strangelet is a hypothetical object consisting of a bound state of roughly equal numbers of up, down, and strange Quarks The size would be For the physics concept see Strange matter. Strange Matter is a Children's book series created by Marty M 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. Ice-nine is a Fictional material conceived by writer Kurt Vonnegut in his novel Cat's Cradle. Scientific American is a Popular science magazine, published (first weekly and later monthly since August 28, 1845, making it 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. The coulomb (symbol C) is the SI unit of Electric charge. It is named after Charles-Augustin de Coulomb.

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

\frac{m_u}{m_d}=0.56\qquad{\rm and}\qquad\frac{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. In Quantum field theory, chiral symmetry is a possible symmetry of the Lagrangian under which the left-handed and right-handed parts Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the 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 In Particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics The absolute values of the masses are currently determined from QCD sum rules (also called spectral function sum rules) and lattice QCD. In Physics, lattice quantum chromodynamics (lattice QCD is a theory of Quarks and Gluons formulated on a space-time lattice. 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 Quantum field theory, the Statistical mechanics of fields and the theory of self-similar geometric structures renormalization refers to a collection

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. In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( 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.

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. In Particle physics, quarkonium (pl quarkonia) designates a flavorless Meson whose constituents are a Quark and its own antiquark 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 Physics, lattice quantum chromodynamics (lattice QCD is a theory of Quarks and Gluons formulated on a space-time lattice.

The top quark is sufficiently heavy that perturbative QCD can be used to determine its mass. Perturbative QCD is a subfield of particle physics in which the theory of strong interactions Quantum Chromodynamics (QCD is studied by using the fact that the strong coupling 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 Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles 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. Tevatron is a circular Particle accelerator at the Fermi National Accelerator Laboratory in Batavia Illinois and is the highest energy particle collider

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. CPT symmetry is a fundamental symmetry of Physical laws under transformations that involve the inversions of charge, parity and 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.

Substructure

Some extensions of the Standard Model begin with the assumption that quarks and leptons have substructure. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their 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. In Particle physics, preons are postulated "point-like" particles conceived to be subcomponents of Quarks and Leptons The word was coined

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. In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( Murray Gell-Mann (born September 15, 1929) is an American Physicist who received the 1969 Nobel Prize in physics for his work In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i 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. Current algebra is a mathematical framework in Quantum field theory where the fields form a Lie algebra under their commutation relations This is a global flavor SU(3) symmetry, which should not be confused with the gauge symmetry of QCD. Special Unit 2In Mathematics, the special unitary group of degree n, denoted SU( n) is the group of n × n

In this scheme the lightest mesons (spin-0) and baryons (spin-½) are grouped together into octets, 8, of flavor symmetry. In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. 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.

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. In Physics, the Eightfold Way is a term coined by American Physicist Murray Gell-Mann for a theory organizing subatomic Baryons Buddhism is a family of beliefs and practices He also chose the name quark and attributed it to the sentence “Three quarks for Muster Mark” in James Joyce's Finnegans Wake. James Augustine Aloysius Joyce (2 February 1882 &ndash 13 January 1941 was an Irish expatriate writer widely considered to be one of the most influential writers of the Finnegans Wake is a fictional work by James Joyce, published in 1939 [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]

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). Richard Phillips Feynman (ˈfaɪnmən May 11 1918 – February 15 1988 was an American Physicist known for the Path integral formulation of quantum In Particle physics, the parton model was proposed by Richard Feynman in 1969 as a way to analyze high-energy Hadron collisions A scaling of deep inelastic scattering cross sections derived from current algebra by James Bjorken received an explanation in terms of partons. 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 James Daniel "Bj" Bjorken (born 1934 is one of the world's foremost theoretical physicists When Bjorken scaling was verified in an experiment in 1969, it was immediately realized that partons and quarks could be the same thing. James Daniel "Bj" Bjorken (born 1934 is one of the world's foremost theoretical physicists With the proof of asymptotic freedom in QCD in 1973 by David Gross, Frank Wilczek and David Politzer the connection was firmly established. In Physics, asymptotic freedom is the property of some gauge theories in which the interaction between the particles such as Quarks, becomes arbitrarily David Jonathan Gross (born February 19, 1941 in Washington DC Frank Anthony Wilczek (born May 15, 1951) is an American theoretical physicist and Nobel laureate. 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. 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 a San Marino citizen Physicist best known for his prediction of the Charm quark with Glashow and Iliopoulos. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles 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. In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. The J/ψ is a Subatomic particle, 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. is a Japanese Physicist well-known for his work on CP-violation. is a Japanese Theoretical physicist well-known for his work on CP-violation. In Particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics In Particle physics, a kaon (/ˈkeɪɒn/ also called K-meson and denoted) is any one of a group of four Mesons distinguished by the fact that they The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles The bottom quark was discovered in 1977 and the top quark in 1996 at the Tevatron collider in Fermilab. Tevatron is a circular Particle accelerator at the Fermi National Accelerator Laboratory in Batavia Illinois and is the highest energy particle collider Fermi National Accelerator Laboratory ( Fermilab) located in Batavia near Chicago, Illinois, is a U

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. Murray Gell-Mann (born September 15, 1929) is an American Physicist who received the 1969 Nobel Prize in physics for his work Later, he found the word "quark" in James Joyce's book Finnegans Wake, and used the spelling but not the pronunciation:

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. James Augustine Aloysius Joyce (2 February 1882 &ndash 13 January 1941 was an Irish expatriate writer widely considered to be one of the most influential writers of the Finnegans Wake is a fictional work by James Joyce, published in 1939

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

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). Onomatopoeia (also spelled onomatopœia, from Greek: ονοματοποιΐα is a Word or a grouping of words that imitates the sound it is describing The word is also a pun on the relationship between Munster and its provincial capital, Cork. Munster ( Irish: An Mhumhain, ənˈvuːnʲ Cúige Mumhan or Mumha) is the southernmost of the four Provinces of Ireland. Cork (Corcaigh is the second largest city in the Republic of Ireland and the island of Ireland 's third most populous city after Dublin and Belfast

See also

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. A quark star or strange star is a hypothetical type of Exotic star composed of Quark matter, or Strange matter.
  3. ^ Nobel Prize in Physics 2004. Nobel Foundation. The Nobel Foundation (Nobelstiftelsen is a private institution founded on 29 June 1900 to manage the finances and administration of the Nobel Prizes. 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. Events 451 - The Battle of Avarayr between Armenian rebels and the Sassanid Empire takes place 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common 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). Murray Gell-Mann (born September 15, 1929) is an American Physicist who received the 1969 Nobel Prize in physics for his work The Quark and the Jaguar. Owl Books, 180. ISBN 978-0805072532.  
  11. ^ Take Our Word For It, page two, Words to the Wise

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