## Abstract

Using the production reactions pd→He3ω and pp→ppω, the Dalitz plot distribution for the ω→π^{+}π^{−}π^{0} decay is studied with the WASA detector at COSY, based on a combined data sample of (4.408±0.042)×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 ϕ. For the first time, a deviation from pure P-wave phase space is observed with a significance of 4.1σ. The deviation is parametrised by a linear term 1+2αZ, with α determined to be +0.147±0.036, consistent with the expectations of ρ-meson-type final-state interactions of the P-wave pion pairs.

Original language | English |
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Pages (from-to) | 418-425 |

Number of pages | 8 |

Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |

Volume | 770 |

DOIs | |

Publication status | Published - 10 Jul 2017 |

## Keywords

- Decays of other mesons
- Light mesons
- Meson–meson interactions
- MU(+)MU(-)GAMMA
- TRANSITION FORM-FACTORS
- DETECTOR
- NA60
- LIGHT VECTOR-MESONS
- DECAYS
- Meson-meson interactions
- PI-PI-SCATTERING
- DISPERSIVE ANALYSIS
- ETA
- PARITY