Mechanism of the fluxional behaviour in (1–5-η-cycloheptadienyl)-(1–5-η-cycloheptatrienyl)iron

The decay η ′ c → η

The decay η ′ c → η c π π. Abstract It is pointed out that the decay of the recently observed charmonium η ′ c resonance, η ′ c → η c π π is simply related to the well studied decay ψ ′ → J/ψ π π and can thus be used for absolute normalization of other decay modes of the η ′ c. The total rate of the discussed decay should be approximately three to four times the corresponding rate for the ψ ′ r...

The η and η ′ mesons in QCD

Hadronic η and η ′ decays

The hadronic decays η, η′ → 3π and η′ → ηππ are investigated within the framework of U(3) chiral effective field theory in combination with a relativistic coupled-channels approach. Final state interactions are included by deriving sand p-wave interaction kernels for meson-meson scattering from the chiral effective Lagrangian and iterating them in a Bethe-Salpeter equation. Very good overall ag...

The η-η′ mixing angle revisited

The value of the η-η′ mixing angle θP is phenomenologically deduced from a rather exhaustive and up-to-date analysis of data including strong decays of tensor and higher-spin mesons, electromagnetic decays of vector and pseudoscalar mesons, J/ψ decays into a vector and a pseudoscalar meson, and other transitions. A value of θP between −17◦ and −13◦ is consistent with the present experimental ev...

- η , η ′ Mixing in B → ππ

An isospin analysis of B → ππ decays yields sin 2α, where α ≡ arg[−VtdV ∗ tb/(VudV ∗ ub)] and Vij is a CKM matrix element, without hadronic uncertainty if isospin is a perfect symmetry. Isospin, however, is broken not only by electroweak effects but also by the u and d quark mass difference. The latter drives π − η, η mixing and converts the isospin-perfect triangle relation between the B → ππ ...