The Lost Tribes of Charmonium

Quigg, Chris

doi:10.1016/j.nuclphysbps.2005.01.016

Cited by 29 publications

(35 citation statements)

References 48 publications

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“…In the charm sector there have also been surprises in the past year, several narrow states like the X(3872) [38] and the D sJ (2317), (2460), (2632) [39]. The X(3872) is a state of hidden charm, that does not fit in with the known structure of charmonium [40]. It sits very close to D * D threshold, and could very well be a tetraquark state made of [cn][cn] , with n = u, d .…”

Section: Figure 12mentioning

confidence: 99%

Swimming with Quarks

Pennington

2005

J. Phys.: Conf. Ser.

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These six lectures, given at the XI Mexican School of Particles and Fields held at Xalapa in August 2004, are on the subject of strong coupling QCD. How this colours and shapes the hadron world in terms of (i) the hadron spectrum, (ii) chiral symmetry breaking, (iii) dynamical mass generation and (iv) confinement, are the topics discussed. P = (−1) L+1 , C = (−1) L+S .Let us first consider the quark model states with S = 1, L = 0 . This gives the vector mesons with J P C = 1 −− . With three light flavours, u, d, s we have nine vector mesons. We expect these to be divided into a flavour octet and flavour singlet, since:The quantum numbers of the nine observed states are shown in Fig. 1. The two states in the middle of the multiplet with I = 0 , the ω and φ , are however not members of an octet and a singlet, respectively, but they magically mix so that they correspond to states of definite quark flavour. We learn this from their decays and from their masses, Fig. 1. The states decay overwhelmingly into pseudoscalar mesons by the creation of uu and dd pairs from the vacuum. This explains why the strange vector state the K * (890) decays to Kπ and the ρ to ππ , as shown in Fig. 2. The I = 0 octet and singlet states would both decay to 3 pions ( G -parity forbids the decay to 2 pions ). While the ω does decay to 3 pions, and has a mass very close to the ρ reflecting their composition of u and d quarks, the φ overwhelmingly decays to KK despite much greater phase space for its 3π mode, Fig. 1, and an ss composition is inferred. This is intimately related to the mass differenceswhich reflect the mass difference between the s quark and the u and d . For a state made of ss quarks to decay to 3π requires the initial strange quarks to annihilate and for all the quarks 2 = 9 : 2 : 1 . (4) Experiment agrees with this very well. Exactly, the same structure of an ideally mixed nonet shown in Fig. 1 applies to the tensor mesons where the quarks combine with S = 1, L = 1 . There the heaviest, the f 2 (1525) (the spin-2 analogue of the φ ) overwhelmingly decays to KK . The f 2 (1270) composed of u and d quarks can decay to KK too by the creation of an ss pair, but strange quarks beingWhile the wavefunction is symmetric under permutations of the colours, it is odd under the interchange of any pair. This explains a longstanding problem of the statistics obeyed by quarks. Quarks were known to have spin-1/2 in order to build the observed hadrons and their Glueballs should exist in a world without quarks. A world that is difficult to study in experiment, but is readily computable in lattice gauge theories. Remarkably such calculations have long shown (see Fig. 6 from [17]) that in a world of pure glue there is a spectrum of colour singlet hadrons. The lightest of these is a scalar (with J P C = 0 ++ ) with mass of 1500-1700 MeV. Though these calculations must be corrected by quark loops to have physical meaning, experiment reveals possible candidates with masses in exactly this same region. The different protagonists (see [18]) bein...

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Section: Figure 12mentioning

confidence: 99%

Swimming with Quarks

Pennington

2005

J. Phys.: Conf. Ser.

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“…The presence of the J/ψ among the decay products of the X(3872) motivates its interpretation as a charmonium state with constituents cc [5][6][7][8][9]. Two possibilities motivated by the proximity of the mass in Eq.…”

Section: Introductionmentioning

confidence: 99%

Decays of theX(3872)intoJ/ψand light hadrons

Braaten

Kusunoki

2005

Phys. Rev. D

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If the X(3872) is a loosely-bound molecule of the charm mesons D 0D * 0 and D * 0D0 , it can decay through the decay of a constituent in a hadronic channel with a nearby threshold, such as J/ψ ω or J/ψ ρ. The differential decay rates of the X into J/ψ π + π − , J/ψ π + π − π 0 , J/ψ π 0 γ, and J/ψ γ are calculated in terms of XJ/ψ ρ and XJ/ψ ω coupling constants using an effective lagrangian that reproduces the decay rates of the ω and the ρ. The dependence of the coupling constants on the binding energy and the total width of the X is determined by a factorization formula. Results from a model by Swanson are used to predict the partial width of X into J/ψ π + π − π 0 as a function of the binding energy and the total width of the X.

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“…Soon after Belle's discovery [40] (and BaBar's confirmation [25]) of the X(3872) resonance it was realized that this particle could not have been identified as a standard charmonium excitation, despite decaying prominently into J/ψρ [135]. The mass of the X being so close to the D 0D * 0 threshold suggests that it can be an example of a hadron molecule characterized by an extremely small binding energy.…”

Section: Flavor Physics and Cp Violationmentioning

confidence: 99%

Particle Physics-Final Report

Kuti

2013

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The Lost Tribes of Charmonium

Cited by 29 publications

References 48 publications

Swimming with Quarks

Swimming with Quarks

Decays of theX(3872)intoJ/ψand light hadrons

Particle Physics-Final Report

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