The φ→ηπ0γ decay

Radiative ϕ decays with derivative interactions

“…We then increase c a0KK up to 14 GeV −1 : the fit turns out to be satisfying in the whole range, see Table III where the mass, the couplings and the on-shell amplitudes A a0πη = A a0πη (M a0 ), A a0KK = A a0KK (M a0 ) defined in Eq. (21)- (22), are reported. In Fig.…”

“…Also in this case we obtain that our analysis is compatible with experimental results of a different source. [22] and black ones from [23]. The solid line corresponds to ca 0 KK = 0 while the dashed one -with the pronounced peak at threshold-to ca 0 KK = 12 GeV −1 .…”

“…[20,21] for the f 0 meson and in Refs. [22,23] for the a 0 meson. The peaked line shapes can be reproduced in virtue of the derivative coupling which enhance the theoretical curves close to threshold.…”

Scalar meson exchange in θ → P0P0γ decays

“…For φ → π 0 ηγ, the branching ratios measured by the SND, CMD-2 and KLOE Collaborations are B(φ → π 0 ηγ) = (8.8 ± 1.4 ± 0.9) × 10 −5 [4], (9.0 ± 2.4 ± 1.0) × 10 −5 [2], and B(φ → π 0 ηγ) = (8.51 ± 0.51 ± 0.57) × 10 −5 (η → γγ) and (7.96 ± 0.60 ± 0.40) × 10 −5 (η → π + π − π 0 ) [5]. Again, in all these cases, the observed mass spectrum shows a significant enhancement at large π 0 η invariant mass that is interpreted as a manifestation of the dominant contribution of the a 0 (980)γ intermediate state.…”

Radiative decays with scalar mesons and in Resonance Chiral Theory

“…The e + e − experiments in Novosibirsk [1,2] and Frascati [3,4] allow one to study the φ(1020) → ππγ (and πηγ) radiative decays. The invariant mass distributions of the pseudoscalar (P ) pairs in these decays are of considerable interest.…”