Experimental evidence for a light and broad scalar resonance in $D^+\to π^-π^+π^+$ decay

Abstract

From a sample of $1172 \pm 61$ $D^+ \to π^- π^+ π^+$ decay, we find $Γ(D^+ \to π^- π^+ π^+) / Γ(D^+ \to K^- π^+ π^+) = 0.0311 \pm 0.0018 ^{+0.0016}_{-0.0026}$. Using a coherent amplitude analysis to fit the Dalitz plot of this decays, we find strong evidence that a scalar resonance of mass $478^{+24}_{-23} \pm 17$ MeV/$c^2$ and width $324^{+42}_{-40} \pm 21$ MeV/$c^2$ accounts for approximately half of all decays.