Study of the $\eta\pi^o$ system in the mass range up to 1200 MeV

TL;DR

This study investigates the $ ext{a}_0(980)$ meson in the $ ext{η} ext{π}^0$ system up to 1200 MeV using partial wave analysis, revealing production mechanisms and exchange contributions in $ ext{π}^- ext{p}$ reactions at high energy.

Contribution

It provides new insights into the production mechanism of the $ ext{a}_0(980)$ meson, confirming the role of $ ho_2$ exchange in the $t$-channel.

Findings

Sharp peak of $a_0(980)$ in S-wave observed.

Dominant production at small momentum transfer $t$.

Supports the $ ho_2$ exchange hypothesis in $a_0(980)$ production.

Abstract

The reaction $\pi^-p \to \eta\pi^o n$ has been studied with GAMS-2000 spectrometer in the secondary 38 GeV/c $\pi^-$-beam of the IHEP U-70 accelerator. Partial wave analysis of the reaction has been performed in the $\eta\pi^o$ mass range up to 1200 MeV. The $a_0(980)$-meson is seen as a sharp peak in S-wave. The $t$-dependence of $a_0(980)$ production cross section has been studied. Dominant production of the $a_0(980)$ at a small transfer momentum $t$ confirms the hypothesis of Achasov and Shestakov about significant contribution of the $\rho_2$ exchange ($I^GJ^{PC}=1^+2^{--}$) in the mechanism of $a_0(980)$ meson production in $t$-channel of the reaction.