Studies on X(4260) and X(4660) particles
Studies on the X(4260) and X(4660) resonant states in an effective lagrangian approach are reviewed. Using a Breit--Wigner propagator to describe their propagation, we find that the X(4260) has a sizable coupling to the $ωχ_{c0}$ channel, while other couplings are found to be negligible. Besides, it couples much stronger to $σ$ than to $f_0(980)$: $|g_{XΨσ}^2/g^2_{XΨf_0(980)}|\sim O(10) \ .$ As an approximate result for X(4660), we obtain that the ratio of $\frac{Br(X\rightarrowΛ_c^+Λ_c^-)}{Br(X\rightarrowΨ(2s)π^+π^-)}\simeq 20$. Finally, taking X(3872) as an example, we also point out a possible way to extend the previous method to a more general one in the effective lagrangian approach.
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