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摘要
A recent quark-model description of X(3872) as an unquenched 2 P-3(1) c (c) over bar state is generalised by now including all relevant meson-meson configurations, in order to calculate the widths of the experimentally observed electromagnetic decays X(3872) -> gamma J/psi and X(3872) -> gamma psi(2S). Interestingly, the inclusion of additional two-meson channels, most importantly (DD star -/+)-D-+/-, leads to a sizeable increase of the c (c) over bar probability in the total wave function, although the D-0(D) over bar (star 0) component remains the dominant one. As for the electromagnetic decays, unquenching strongly reduces the gamma psi(2S) decay rate; yet it even more sharply enhances the gamma J/psi rate, resulting in a decay ratio compatible with one experimental observation but in slight disagreement with two others. Nevertheless, the results show a dramatic improvement as compared to a quenched calculation with the same confinement force and parameters. Concretely, we obtain Gamma (X(3872) -> gamma psi(2S)) = 28.9 keV and Gamma (X(3872) -> gamma J/psi) = 24.7 keV, with branching ratio R-gamma psi = 1.17.
- 出版日期2015-1-23
