Han-Qing Zheng — Page 3

arXiv2013

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.

hep-ph↗

arXiv2012

Study of η-η' mixing from radiative decay processes

We perform a thorough analysis of the VPγ(γ*) and Pγγ(γ*) decays in the resonance chiral theory, where V stand for the vector resonances ρ, K*, ω, ϕ, P stand for π, K, η, η' and γ* subsequently decays into lepton pairs. Upon imposing QCD short-distance constraints on resonance couplings, the ω-> πγ(γ*), ρ-> πγ(γ*), K^{*0} -> K^0γprocesses only depend on one free parameter and π-> γγ(γ*) can be completely predicted. The four mixing parameters of the η-η' system, i.e. two mixing angles \theta8, \theta0 and two decay constants F8, F0, are determined from radiative decays involving ηor η'. The higher order low energy constants of the pseudo-Goldstone Lagrangian in the chiral anomaly sector are predicted by integrating out heavy resonances. We also predict the decay widths of ρ-> πe^+ e^-, η' -> γe^+ e^- and ϕ-> ημ^+ μ^-, which can be compared with the future measurement in these channels.

hep-ph↗