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

TL;DR

This study provides experimental evidence for a light, broad scalar resonance in the decay of D+ mesons to three pions, revealing its properties and significant contribution to the decay process.

Contribution

The paper reports the first evidence of a light scalar resonance in D+ decays, with detailed measurements of its mass, width, and impact on decay dynamics.

Findings

Identification of a scalar resonance at 478 MeV/c^2

Resonance accounts for about half of D+ to 3π decays

Measured resonance parameters with uncertainties

Abstract

From a sample of $1172 \pm 61$ $D^+ \to \pi^- \pi^+ \pi^+$ decay, we find $\Gamma (D^+ \to \pi^- \pi^+ \pi^+) / \Gamma (D^+ \to K^- \pi^+ \pi^+) = 0.0311 \pm 0.0018 ^{+0.0016}_{-0.0026}$. 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.