No Arabic abstract
We revisit the coupled channel $Kbar{K}$ interactions and dynamically generate the resonances $f_0(980)$ and $a_0(980)$ within both the isospin and the physical bases. The $f_0(980)-a_0(980)$ mixing effects are generated in the scattering amplitudes of the coupled channels with the physical basis, which exploits the important role of the $Kbar{K}$ channel in the dynamical nature of these resonances. With the scattering amplitudes obtained, we investigate the $f_0(980)$ and $a_0(980)$ contributions to the $J/psito gammaetapi^0$, $J/psito gammapi^+pi^-$ and $J/psito gammapi^0pi^0$ radiative decays through the final-state interactions. We obtain the corresponding branching fractions $Br(J/psito gamma a_0(980) to gammaetapi^0) = (0.47pm0.05) times 10^{-7}$, $Br(J/psito gamma f_0(980) to gammapi^+pi^-) = 0.37 times 10^{-7} - 1.98 times 10^{-6}$, $Br(J/psito gamma f_0(980) to gammapi^0pi^0) = 0.18 times 10^{-7} - 9.92 times 10^{-7}$, and predict $Br(J/psito gamma a_0(980)) = 1.72 times 10^{-8} - 3.07times 10^{-7}$ and $Br(J/psito gamma f_0(980)) = 1.86 times 10^{-8} - 1.89times 10^{-5}$. These fractions are within the upper limits of the experimental measurements.
Based on a sample of $1.31 times 10^9$ $J/psi$ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays $eta^prime rightarrow pi^+pi^-pi^0$ and $eta^prime rightarrow pi^0pi^0pi^0$ is performed. A significant $P$-wave contribution from $eta^prime rightarrow rho^{pm} pi^{mp}$ is observed for the first time in $eta^prime rightarrow pi^+pi^-pi^0$. The branching fraction is determined to be ${mathcal B}(eta^prime rightarrow rho^{pm}pi^{mp})=(7.44pm0.60pm1.26pm1.84)times 10^{-4}$, where the first uncertainty is statistical, the second systematic, and the third model dependent. In addition to the nonresonant $S$-wave component, there is a significant $sigma$ meson component. The branching fractions of the combined $S$-wave components are determined to be ${mathcal B}(eta^prime rightarrow pi^+pi^-pi^0)_S=(37.63pm0.77pm2.22pm4.48)times 10^{-4}$ and ${mathcal B}(eta^prime rightarrow pi^0pi^0pi^0)=(35.22pm0.82pm2.54)times 10^{-4}$, respectively. The latter one is consistent with previous BESIII measurements.
Based on a sample of $1.31 times 10^9$ $J/psi$ events collected with the BESIII detector at the BEPCII collider, Dalitz plot analyses of selected 79,625 $etarightarrowpi^{+}pi^{-}pi^0$ events, 33,908 $etarightarrowpi^0pi^0pi^0$ events and 1,888 $eta^{prime}rightarrowpi^0pi^0pi^0$ events are performed. The measured matrix elements of $etarightarrowpi^+pi^-pi^0$ are in reasonable agreement with previous measurements. The Dalitz plot slope parameters of $etarightarrowpi^0pi^0pi^0$ and $eta^{prime}rightarrowpi^0pi^0pi^0$ are determined to be $-0.055 pm 0.014 pm 0.004$ and $-0.640 pm 0.046 pm 0.047$, respectively, where the first uncertainties are statistical and the second systematic. Both values are consistent with previous measurements, while the precision of the latter one is improved by a factor of three. Final state interactions are found to have an important role in those decays.
We report the measurement of the ratio $Gamma(eta to pi^+pi^-gamma)/Gamma(eta to pi^+pi^-pi^0)$ analyzing a large sample of $phi to eta gamma$ decays recorded with the KLOE experiment at the DA$Phi$NE $e^+ e^-$ collider, corresponding to an integrated luminosity of 558 pb$^{-1}$. The $eta to pi^+pi^-gamma$ process is supposed to proceed both via a resonant contribution, mediated by the $rho$ meson, and a non resonant direct term, connected to the box anomaly. The presence of the direct term affects the partial width value. Our result $R_{eta}=Gamma(eta to pi^+ pi^- gamma)/Gamma(eta to pi^+ pi^- pi^0)= 0.1838pm 0.0005_{stat} pm 0.0030_{syst}$ is in agreement with a recent CLEO measurement, which differs by more 3 $sigma$ from the average of previous results.
Using a sample of $448.1times10^{6}$ $psi(3686)$ events collected with the BESIII detector, a search for the isospin violating decay $eta_{c}topi^{+}pi^{-}pi^{0}$ via $psi(3686)togammaeta_{c}$ is presented. No signal is observed, and the upper limit on $mathcal{B}(psi(3686)to gammaeta_{c}to gammapi^{+}pi^{-}pi^{0} )$ is determined to be $1.6times10^{-6}$ at the $90%$ confidence level. In addition, a search for $eta(1405)to f_{0}(980)pi^{0}$ in $psi(3686)$ radiative decays is performed. No signal is observed, and the branching fraction $mathcal{B}(psi(3686)togammaeta(1405)to gamma f_{0}(980)pi^{0}togamma pi^+pi^-pi^0 )$ is calculated to be less than $ 5.0times10^{-7}$ at the $90%$ confidence level.
An amplitude analysis of the $pi^{0}pi^{0}$ system produced in radiative $J/psi$ decays is presented. In particular, a piecewise function that describes the dynamics of the $pi^{0}pi^{0}$ system is determined as a function of $M_{pi^{0}pi^{0}}$ from an analysis of the $(1.311pm0.011)times10^{9}$ $J/psi$ decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the $pi^0pi^0$ system while making minimal assumptions about the properties or number of poles in the amplitude. Such a model-independent description allows one to integrate these results with other related results from complementary reactions in the development of phenomenological models, which can then be used to directly fit experimental data to obtain parameters of interest. The branching fraction of $J/psi to gamma pi^{0}pi^{0}$ is determined to be $(1.15pm0.05)times10^{-3}$, where the uncertainty is systematic only and the statistical uncertainty is negligible.