Charmonium: Comparison with experiment

Abstract

The charmonium model, formulated in detail in an earlier publication, is compared in a comprehensive fashion with the data on the $ family. The parameters of the "naive" model, in which the system is described as a cF pair, are determined from the observed positions of $, +', and the P states. The model then yields a successful description of the spectrum of spin-triplet states above the charm threshold. It also accounts for the ratio of the leptonic widths of $' and +. When the cF potential is applied to the 'T family, it accounts, without any readjustment of parameters, for the positions of the 2s and 3s levels and for the leptonic widths of 'T and T' relative to that of q. The model does not give acceptable values of the absolute leptonic widths, a shortcoming which is ascribed to large quantum-chromodynamic corrections to the van Royen-Weisskopf formula. The calculated E 1 rates are about twice the values observed in the + family. This naive model is also extended with considerable success to mesons composed of one heavy and one light quark. A significant extension of the model is achieved by incorporating coupling to charmedmeson decay channels. This gives a satisfactory understanding of +(3772) as the 13D, c? state, mixed via open and closed decay channels to 23S. The model has decay amplitudes that are oscillatory functions of the decay momentum; these oscillations are a direct consequence of the radial nodes in the c? parent states. These amplitudes provide a qualitative understanding of the observed peculiar branching ratios into various charmed-meson channels near the resonance at 4.03 GeV, which is assigned to 33S. The coupling of the cF states below the charm threshold to closed decay channels modifies the bound states and leads to reduction of about 20% in E 1 rates in comparison to those of the naive model.

The hidden-charm pentaquark and tetraquark states

“…They suggested this new resonance X(3823) as the 1 3 D 2 charmonium state with J PC = 2 −− . The mass and radiative decay behavior agree with the theoretical predictions for the 1 3 D 2 state [113,114,115,17,116,117]. Recently, the BESIII Collaboration confirmed the X(3823) resonance in the process of e + e − → π + π − X(3823) → π + π − γχ c1 at 6.2σ, with a mass (3821.7 ± 1.3 ± 0.7) MeV and width less than 16 MeV at the 90% C.L.…”

Aspects of the screening length and drag force in two alternative gravity duals of the quark-gluon plasma

“…Quarkonium is bound state of the heavy quark and antiquark pair. To estimate the energy and radius of these bound states, one can solve the Schrödinger equation with the non-relativistic empirical potential [2] V (r, T = 0) = σr − α eff r…”

“…In the hot quark-gluon plasma, the deconfined charges would modify the interaction between the heavy quark pair such that we expect the colour-screened potential [3] V (r, T ) = (σr D (T )) 1 − e −r/r D (T ) − α eff r e −r/r D (T ) (2) where r D (T ) is the screening radius. When the temperature increases, the screening radius r D (T ) decreases.…”

Probing Y(4260) as the \(\bar{D}D_{1} + c.c.\) Hadronic Molecule State in e+e− Annihilations

“…Besides, it seems that the inclusive cross section lineshape for e + e − annihilations around the Y(4260) mass region does not have any peaking structures. It should also be noted that the mass of Y(4260) is not consistent with any vector charmonium states in the traditional potential quark model [5][6][7].…”