QCD sum rules for theX(3872)as a mixed molecule-charmonium state

Abstract

We use QCD sum rules to test the nature of the meson Xð3872Þ, assumed to be a mixture between charmonium and exotic molecular ½c "q½q " c states with J PC ¼ 1 þþ . We find that there is only a small range for the values of the mixing angle that can provide simultaneously good agreement with the experimental value of the mass and the decay width, and this range is 5 0 13 0 . In this range we get m X ¼ ð3:77 AE 0:18Þ GeV and ÀðX ! J=c þ À Þ ¼ ð9:3 AE 6:9Þ MeV, which are compatible, within the errors, with the experimental values. We, therefore, conclude that the Xð3872Þ is approximately 97% a charmonium state with 3% admixture of $88% D 0 D Ã0 molecule and $12% D þ D ÃÀ molecule.

The hidden-charm pentaquark and tetraquark states

“…To reproduce the small width of the X(3872), it was considered as a mixture between charmonium and molecular state with J PC = 1 ++ in Ref. [560]. They found a small mixing angle 5 • ≤ θ ≤ 13 • to reproduce the parameters m X = (3.77 ± 0.18) GeV and Γ(X → J/ψπ + π − ) = (9.3 ± 6.9) MeV.…”

Mixed Charmonium-Molecule Interpretation for the Y (3940) State

“…where Q 2 = −q 2 , and the function H(Q 2 ) represents the contribution of the pole-continuum transitions [15,22,23,24]. The…”

“…Here we study the Y (3940), within QCDSR approach, using a mixed charmoniummolecule current, following the works in Refs. [15,16,17,18] where the states X(3872) and Y (4260) were considered as molecule-charmonium states.…”

Hidden-charm and bottom meson-baryon molecules coupled with five-quark states

“…[53] and references therein). In addition, theDΛ c andD * Λ c thresholds are also located just below theD ( * ) Σ may be explained by this admixture picture of a cc core plus higher Fock components due to the coupling to the meson-meson continuum [56,[65][66][67][68][69][70][71][72][73][74][75][76][77][78]. For those interested in X, Y , and Z exotic states, a general review can be found in [56].…”