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Encyclopedia > Exotic meson
Identities and classification of possible tetraquark mesons. Green denotes I = 0 states, purple, I = 1/2 and red, I = 1. The vertical axis is the mass.
Identities and classification of possible tetraquark mesons. Green denotes I = 0 states, purple, I = 1/2 and red, I = 1. The vertical axis is the mass.

Non-quark model mesons include: Image File history File links Exotics. ... Image File history File links Exotics. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ...

  1. exotic mesons, which have quantum numbers not possible for mesons in the quark model
  2. glueballs or gluonium, which have no valence quarks at all
  3. tetraquarks, which have two valence quark-antiquark pairs,
  4. hybrid mesons, which contain a valence quark-antiquark pair and one or more gluons.

All of these can be classed as mesons, because they are hadrons and carry zero baryon number. Of these, glueballs must be flavour singlets, that is, have zero isospin, strangeness, charm, bottomness and topness. Like all particle states, they are specified by the quantum numbers which label representations of the Poincaré symmetry, ie, JPC (where J is the angular momentum, P is the intrinsic parity and C is the charge conjugation parity) and by the mass. One also specifies the isospin I of the meson. A quantum number describes the energies of electrons in atoms. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ... Quarks are one of the two basic constituents of matter in the Standard Model of particle physics. ... In particle physics, gluons are vector gauge bosons that mediate strong color charge interactions of quarks in quantum chromodynamics (QCD). ... In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... In particle physics, the baryon number is an approximate conserved quantum number. ... Isospin (isotopic spin, isobaric spin) is a physical quantity which is mathematically analogous to spin. ... In particle physics, strangeness is the number of anti-strange quarks minus the number of strange quarks in a particle. ... For other uses of this term, see: Quark (disambiguation) 1974 discovery photograph of a possible charmed baryon In particle physics, the quarks are subatomic particles thought to be elemental and indivisible. ... The bottom quark is a third-generation quark with a charge of -(1/3)e. ... The top quark is a third-generation quark with a charge of +(2/3)e. ... In physics and mathematics, the Poincaré group is the group of isometries of Minkowski spacetime. ... Gyroscope. ... In physics, in particular quantum mechanics, the intrinsic parity is a phase factor that arises as an eigenvalue of the parity operation (a reflection about the origin). ... C-symmetry means the symmetry of physical laws over a charge-inversion transformation. ... Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ...


Typically, every quark model meson comes in SU(3) flavour nonets— an octet and a flavour singlet. A glueball shows up as an extra (supernumerary) particle outside the nonet. In spite of such seemingly simple counting, the assignment of any given state as a glueball, tetraquark or hybrid remains tentative even today. Even when there is agreement that one of several states is one of these non-quark model mesons, the degree of mixing, and the precise assignment is fraught with uncertainties. There is also the considerable experimental labour of assigning quantum numbers to each state and cross checking them in other experiments. As a result, all assignments outside the quark model are tentative. The remainder of this article outlines the situation as it stood at the end of 2004. In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ... Flavour (or flavor) is a quantum number of elementary particles related to their weak interactions. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ...

Contents


Lattice predictions

Lattice QCD predictions for glueballs are now fairly stable, at least when virtual quarks are neglected. The two lowest states are It has been suggested that lattice field theory be merged into this article or section. ... In physics, a virtual particle is a particle-like abstraction used in some models of quantum field theory. ...

0+ + with mass of 1611±163 MeV
2+ + with mass of 2232±310 MeV

The 0− + and exotic glueballs such as 0− − are all expected to lie above 2 GeV. Glueballs are necessarily isoscalar, ie, have isospin I=0. 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. ... 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. ... A GEV (or Ground Effect Vehicle) is vehicle that takes advantage of the aerodynamic principle of ground effect (or Wing-in-ground). ... Isospin (isotopic spin, isobaric spin) is a physical quantity which is mathematically analogous to spin. ...


The ground state hybrid mesons0− +, 1− +, 1− − and 2− + all lie a little below 2 GeV. The hybrid with exotic quantum numbers 1− + is at 1.9±0.2 GeV. The best lattice computations to date are made in the quenched approximation, which neglects virtual quarks loops. As a result, these computations miss mixing with meson states. It has been suggested that lattice field theory be merged into this article or section. ...


The 0+ + states

The data show five isoscalar resonances—

f0(600), f0(980), f0(1370), f0(1500) and f0(1710)

Of these the f0(600) is usually identified with the σ of chiral models. The decays and production of f0(1710) give strong evidence that it is also a meson. In nuclear physics, the chiral model is a phenomenological model describing mesons in the chiral limit where the masses of the quarks goes to zero (without mentioning quarks at all). ...


Glueball candidate

The f0(1370) and f0(1500) cannot both be a quark model meson, because one is supernumerary. The production of the higher mass state in two photon reactions such as 2γ → 2π or 2γ → 2K reactions is highly suppressed. The decays also give some evidence that one of these could be a glueball. In quantum physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field (light). ...


Tetraquark candidate

The f0(980) has been identified by some authors as a tetraquark meson, along with the I=1 states a0(980) and κ0(800).Two longlived (narrow in the jargon of particle spectroscopy) states: the scalar (0++) state DsJ(2317) and the vector (1+) meson DsJ(2460), observed at CLEO and BaBar, have also been tentatively identified as tetraquark states. However, for these, other explanations are possible. Cleo is a female given name that is short for Cleopatra and an alternate spelling for Clio. ... Babar can refer to: Babar the Elephant The BaBar Experiment at the Stanford Linear Accelerator Babur (also spelled Baber or Babar), 16th-century ruler of India and founder of the Mogul Empire Babar Island, an island of Indonesia Safir A Babar, This is a disambiguation page — a navigational aid which...


The 2+ + states

Two isoscalar states are definitely identified— f2(1270) and the f'2(1525). No other states have been consistently identified by all experiments. Hence it is difficult to say more about these states.


The 1− + exotics and other states

The two isovector exotics π1(1400) and π1(1600) seems to be well established experimentally. They are clearly not glueballs, but could be either a tetraquark or a hybrid. The evidence for such assignments is weak.


The 0− + π(1800), 1− − ρ(1900) and the 2− + η2<(1870) are fairly well identified states, which have been tentatively identified as hybrids by some authors. If this identification is correct, then it is a remarkable agreement with lattice computations, which place several hybrids in this range of masses.


See also

In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ... 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 nucleons), as well as a number of unstable, heavier particles (called hyperons). ... Quarks are one of the two basic constituents of matter in the Standard Model of particle physics. ... In particle physics, gluons are vector gauge bosons that mediate strong color charge interactions of quarks in quantum chromodynamics (QCD). ... Exotic hadrons are divided into two groups: exotic baryons and exotic mesons. ... Ordinary baryons are bound states of 3 quarks. ... Quantum chromodynamics (QCD) is the theory of the strong interaction, a fundamental force describing the interactions of the quarks and gluons found in nucleons (such as the proton and neutron). ... Flavour (or flavor) is a quantum number of elementary particles related to their weak interactions. ... The QCD vacuum is the vacuum state of quantum chromodynamics (QCD). ...

References and external links

  • Particle Data Group: non quark-antiquark candidates (S. Eidelman et al, Physics Letters B 592, 2004, p 1 and 2005 web update)


Particles in physics - composite particles
Hadrons: Baryons (list) | Mesons (list)

Baryons: Nucleons | Hyperons | Exotic baryons | Pentaquarks
Mesons: Pions | Kaons | Quarkonium | Exotic mesons
Atomic nuclei | Atoms | Molecules 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. ... Elementary particles An elementary particle is a particle with no measurable internal structure, that is, it is not a composite of other particles. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called nucleons), as well as a number of unstable, heavier particles (called hyperons). ... A list of baryons. ... In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... A list of mesons. ... In physics a nucleon is a collective name for the two baryons: the neutron and the proton. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called nucleons), as well as a number of unstable, heavier particles (called hyperons). ... 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. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: π0, π+ 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 high energy physics, a quarkonium (pl. ... A semi-accurate depiction of the helium atom. ... Properties For other uses, see Atom (disambiguation). ... In chemistry, a molecule is an aggregate of at least two atoms in a definite arrangement held together by special forces. ...


  Results from FactBites:
 
Exotic meson - Wikipedia, the free encyclopedia (568 words)
exotic mesons, which have quantum numbers not possible for mesons in the quark model
All of these can be classed as mesons, because they are hadrons and carry zero baryon number.
Even when there is agreement that one of several states is one of these non-quark model mesons, the degree of mixing, and the precise assignment is fraught with uncertainties.
Meson - Wikipedia, the free encyclopedia (1088 words)
In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin.
Pseudoscalar mesons (spin 0) have the lowest rest energy, where the quark and antiquark have opposite spin, and then the vector mesons (spin 1), where the quark and antiquark have parallel spin.
Mesons were originally predicted as carriers of the force that bind protons and neutrons together.
  More results at FactBites »

 
 

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