Dalitz plot distribution of the $etatopi^+pi^-pi^0$ decay is determined using a data sample of $1.2cdot 10^7$ $eta$ mesons from $pdto ^3textrm{He}eta$ reaction at 1 GeV collected by the WASA detector at COSY.
Using $1.6$ fb$^{-1}$ of $e^+ e^-tophitoetagamma$ data collected with the KLOE detector at DA$Phi$NE, the Dalitz plot distribution for the $eta to pi^+ pi^- pi^0$ decay is studied with the worlds largest sample of $sim 4.7 cdot 10^6$ events. The Dali
tz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables $X$ and $Y$. The experiment is sensitive to all charge conjugation conserving terms of the expansion, including a $gX^2Y$ term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements.
Using the production reactions $pdto {}^3mbox{He},omega$ and $ppto ppomega$, the Dalitz plot distribution for the $omega to pi^+ pi^- pi^0$ decay is studied with the WASA detector at COSY, based on a combined data sample of $ (4.408pm 0.042) times 10
^4$ events. The Dalitz plot density is parametrised by a product of the $P$-wave phase space and a polynomial expansion in the normalised polar Dalitz plot variables $Z$ and $phi$. For the first time, a deviation from pure $P$-wave phase space is observed with a significance of $4.1sigma$. The deviation is parametrised by a linear term $1+2alpha Z$, with $alpha$ determined to be $+0.147pm0.036$, consistent with the expectations of $rho$-meson-type final-state interactions of the $P$-wave pion pairs.
We have studied, with the KLOE detector at the DA$Phi$NE $Phi$-Factory, the dynamics of the decay $etatopi^+pi^-pi^0$ using $eta$ mesons from the decay $phitoetagamma$ for an integrated luminosity ${mathcal L}$ = 450 pb$^{-1}$. From a fit to the Dali
tz plot density distribution we obtain a precise measurement of the slope parameters. An alternative parametrization relates the $pi^+pi^-pi^0$ slopes to that for $etato 3pi^0$ showing the consistency of KLOE results for both channels. We also obtain the best confirmation of the $C$-invariance in the $etatopi^+pi^-pi^0$ decay.
We have studied, with the KLOE detector at the DA$Phi$NE $Phi$-Factory, the dynamics of the decay $etatopi^+pi^-pi^0$ using data from the radiative $phitoetagamma$ decay for an integrated luminosity $L = 450 textrm{pb^{-1}}$. From a fit to the Dalitz
plot density distribution we obtain a precise measurement of the slope parameters. This should allow to improve the knowledge of the decay amplitude which is sensitive to the u-d quark mass difference. We also present new best results on the C-violating asymmetries in the $etatopi^+pi^-pi^0$ decay.
A violation of mirror symmetry in the $etatopi^+pi^-pi^0$ Dalitz plot has long been recognized as a signal of C and CP violation. Here we show how the isospin of the underlying C- and CP-violating structures can be reconstructed from their kinematic
representation in the Dalitz plot. Our analysis of the most recent experimental data reveals, for the first time, that the C- and CP-violating amplitude with total isospin $I=2$ is much more severely suppressed than that with total isospin $I=0$.