Mass and width of sigma(750) scalar meson from measurements of pi(-)p->pi(-)pi(+)n on polarized target

Abstract

Model independent amplitude analyses of $π^- p_\uparrow \to π^- π^+ n$ on polarized target at 17.2 GeV/c reveal resonant structure of S-wave transversity amplitudes $|\bar S|^2Σ$ and $|S|^2Σ$ near 750 MeV. Simultaneous fit to $|\bar S|^2Σ$ and $|S|^2Σ$ with a single $σ$ pole yields $m_σ= 775 \pm 17$ MeV and $Γ_σ= 147 \pm 33$ MeV. Simultaneous fit with two common $σ$ poles yields a lower $χ^2/dpt$. Their resonance parameters are $m_σ= 786 \pm 24$ MeV, $Γ_σ= 130 \pm 47$ MeV and $m_{σ^\prime} = 670 \pm 30$ MeV, $Γ_{σ^\prime} = 59 \pm 58$ MeV.