Understanding the X(3872) with QCD sum rules
Instituto de Física, Universidade de São Paulo,
C.P. 66318, 05389-970
São Paulo, SP, Brazil
The nature of the meson X(3872) is still under debate. Here we assume it to be a mixture between charmonium and exotic molecular [cq][qc] states with JPC = 1++ . We ﬁnd that there is only a small range for the values of the mixing angle, θ, that can provide simultaneously good agreement with the experimental value of the mass and the decay width, and this range is 50 ≤ θ ≤ 130 . In this range we get mX = (3.77 ± 0.18) GeV and Γ(X → J/ψπ+π−) = (9.3 ± 6.9) MeV, which are compatible, within the errors, with the experimental values. We, therefore, conclude that the X(3872) is approximately 97% a charmonium state with 3% admixture of ∼88% D0 D∗0 molecule and ∼12% D+ D∗− molecule.
© Owned by the authors, published by EDP Sciences, 2010