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Encyclopedia > Charmonium
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In high energy physics, a charmonium (plural charmonia) is a flavorless meson constituted by a charm quark and an anti-charm quark. Different charmonium states can be discriminated in function of its quantum numbers: S, L, and J (or equivalently, J, P and C). Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. ... In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... 1974 discovery photograph of a possible charmed baryon, now identified as the Σc++ In particle physics, the quarks are subatomic particles thought to be elemental and indivisible. ... A quantum number is a number used to parametrise certain properties of particles or other systems in quantum mechanics. ... In physics, spin is an intrinsic angular momentum associated with microscopic particles. ... The Azimuthal quantum number (or orbital angular momentum quantum number) l is a quantum number for an atomic orbital which determines its orbital angular momentum. ... The total angular quantum momentum numbers parameterize the total angular momentum of a given electron, by combining its orbital angular momentum and its intrinsic angular momentum (i. ... Parity is a concept of equality of status or functional equivalence. ... C parity or charge parity is a multiplicative quantum number of some particles that describes its behavior under a symmetry operation of charge conjugation (see C-symmetry). ...


Charmonium states JPC = 1−− can be produced directly from electron-positron collisions —as they have the same quantum numbers as the photon— via the process: The total angular quantum momentum numbers parameterize the total angular momentum of a given electron, by combining its orbital angular momentum and its intrinsic angular momentum (i. ... Parity is a concept of equality of status or functional equivalence. ... C parity or charge parity is a multiplicative quantum number of some particles that describes its behavior under a symmetry operation of charge conjugation (see C-symmetry). ... The photon can be perceived as a wave or a particle, depending on how it is measured In physics, the photon (from Greek φοτος, meaning light) is a quantum of the electromagnetic field, for instance light. ...

Non-1−− forms are then usually studied from radiative decays:

Alternatively, proton-antiproton annhilation allows all charmonium states to be be produced.


List of some charmonium states

In the following table, the same particle can be named with the spectroscopic notation or with its mass. In some cases excitation series are used: Ψ' is the first excitation of Ψ (for historical reasons, this one is called J/ψ particle); Ψ" is a second excitation, and so on. That is, names in the same cell are synonymous.


Some of the states are predicted, but have not been identified; others are unconfirmed. Particle X(3872) quantum numbers are unknown; its identity is debated. It may be:

  • a candidate for the 13D2 state;
  • a charmonium hybrid state;
  • a molecule.
Term symbol IG(JPC) Particle mass (MeV)
11S0 0+(0−+) ηc(1S), or ηc(2980) 2979.6±1.2
13S1 0(1−−) J/ψ(1S) 3096.916±0.011
11P1 0(1+−) hc(1P) 3526.2*
13P0 0+(0++) χc0(1P) 3415.2
13P1 0+(1++) χc1(1P) 3510.5
13P2 0+(2++) χc2(1P) 3556.3
21S0 0+(0−+) ηc(2S), or 3654*
23S1 0(1−−) ψ(3686) 3686.093±0.034
11D2 0+(2−+) ηc2(1D)
13D1 0(1−−) ψ(3770) 3770.0±2.4
13D2 0(2−−) ψ(3836) 3836±13
13D3 0(3−−) ψ3(1D)
21P1 0(1+−) hc(2P)
23P0 0+(0++) χc0(2P)
23P1 0+(1++) χc1(2P)
23P2 0+(2++) χc2(2P)
 ???? 0?(??) X(3872) 3872.0

Notes: The title given to this article is incorrect due to technical limitations. ...

* Needs confirmation.
Predicted, but not yet identified.
Candidate. Confirmation needed.
Interpretation as a 1−− charmonium state not favored.

External links

  • cc-bar mesons (http://pdg.lbl.gov/2004/listings/mxxxcomb.html#mesonsccbarres)

  Results from FactBites:
 
Quarkonium - Wikipedia, the free encyclopedia (843 words)
Examples of quarkonia are the J/ψ (which is a charmonium, or charm quark/anti-charm quark state) and the Υ (a bottomonium, or bottom quark/anti-bottom quark state).
This usage is because the lighter quarks (up, down, and strange) have very similar masses, compared to the heavier quarks, and so the physical states actually seen in experiments are quantum mechanical mixtures of the light quark states.
For charmonium masses the agreement is not as good, but the LQCD community is actively working on improving their techniques.
  More results at FactBites »

 
 

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