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Measurement of the $omega to pi^+ pi^- pi^0$ Dalitz plot distribution

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 نشر من قبل Lena Heijkenskj\\\"old
 تاريخ النشر 2016
  مجال البحث
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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.



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