Tests of isospin symmetry breaking at ϕ(1020)\phi (1020) meson factories

In a model of isospin symmetry breaking we obtain the ($e^{-} e^{+} \rightarrow \pi^{-} \pi^{+}$) amplitude $Q$ and the isospin $I=0$ and $I=1$ relative phase $\psi$ at the $\phi (1020)$ resonance in aproximate agreement with experiment. The model predicts \Gamma(\phi \rightarrow \omega \pi^{0}) \approx 4 \cdot 10^{-4} \;\mbox{MeV}. We have also obtained \Gamma (\phi \rightarrow \eta' \gamma)=5.2 \cdot 10^{-4} \;\mbox{MeV}. Measuring this partial width would strongly constrain $\eta$-$\eta'$ mixing. The branching ratios $BR$ of the isospin violating decays $\rho^{+} \rightarrow \pi^{+} \eta$ and $\eta' \rightarrow \rho^{\pm} \pi^{\mp}$ are predicted to be $BR(\rho^{+} \rightarrow \pi^{+} \eta)=3 \cdot 10^{-5}$ and $BR(\eta' \rightarrow \rho^{\pm} \pi^{\mp})=4 \cdot 10^{-3}$, respectively, leading to $BR[\phi \rightarrow \rho^{\pm} \pi^{\mp} \rightarrow (\pi^{\pm} \eta)\pi^{\mp} \rightarrow (\pi^{\pm} \gamma \gamma)\pi^{\mp}]=10^{-6}$ and $BR[\phi \rightarrow \eta' \gamma \rightarrow (\rho^{\pm} \pi^{\mp})\gamma]=2\cdot 10^{-6}$.Comment: 11 pages 2 Figures ( not included available on request ), Latex, Karlsruhe TTP42-9