Strong decays of χcJ(2P) and χcJ(3P)

Radially excited states of $$\eta _c$$ η c

“…Here γ n = 4.19 for uū, dd pairs and γ s = γ n / √ 3 for ss pairs, which values are different from Refs. [4,7].…”

“…The running strong-coupling constants are taken from Ref. [7] and the other parameters are taken from Ref. [16].…”

“…The quantum numbers of X (3872) were fixed recently, I G (J PC ) = 0 + (1 ++ ), so it is a good candidate of χ c1 (2P) [10] although there are also some arguments as regards this assignment [11][12][13]. The explanations of X (3940) as η c (3S) [14], X (4140) as χ c0 (3P) [7] were also proposed recently. However, about half of the cc states remain unassigned.…”

Quarkonium h states as arbiters of exoticity

“…Indeed, the X(3872) has long been argued to have at least a substantial χ c1 (2P ) component, while the X(3915) was briefly listed by the Particle Data Group as χ c0 (2P ) until serious doubts were raised about this identification (especially its lack of DD final states) [3][4][5]; for example, X(3915) might even be the lightest ccss state [7]. The crucial importance of sorting out the states in the 2P charmonium sector, in order to determine which states are (mostly) exotic and which are not, was emphasized as a central experimental goal in Ref.…”

A New Hadron Spectroscopy

“…For states above open-charmed threshold, like the χ ′ c2 and, depending on its mass, the χ ′ c1 , potential model predictions are modified by couplings to on-mass-shell, open-charmed meson pair configurations. However, three different methods for computing these effects all find that they tend to suppress the χ ′ c2 mass while increasing that of the χ ′ c1 and, thereby, reducing (not increasing) this splitting to values that are below potential-model based expectations [88,97,98]. A second problem with the X(3872) = χ ′ c1 assignment is that the measured upper limit on its natural width (Γ X(3872) < 1.2 MeV) is only slightly above the natural width of the "ground-state" χ c1 : Γ χ c1 = 0.84 ± 0.04 MeV.…”