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arXiv · 1608.01447

Three-body final state interaction in $\eta \to 3 \pi$ updated

P. Guo·I. V. Danilkin·C. Fernández-Ramírez·V. Mathieu·A. P. Szczepaniak
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Abstract

In view of the recent high-statistic KLOE data for the $\eta \to \pi^+ \pi^- \pi^0$ decay, a new determination of the quark mass double ratio has been done. Our approach relies on a dispersive model that takes into account rescattering effects between three pions via subenergy unitarity. The latter is essential to reproduce the Dalitz plot distribution. A simultaneous description of the KLOE and WASA-at-COSY data is achieved in terms of just two real parameters. From a global fit, we determine $Q=21.6 \pm 1.1$. The predicted slope parameter for the neutral channel $\alpha=-0.025\pm 0.004$ is in reasonable agreement with the PDG average value.

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P. Guo, I. V. Danilkin, C. Fernández-Ramírez, V. Mathieu, A. P. Szczepaniak. 2016-08-04. Three-body final state interaction in $\eta \to 3 \pi$ updated. https://doi.org/10.1016/j.physletb.2017.05.092

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