Dalitz Plot Analysis of the Decay ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ and Indication of a Low-Mass Scalar $K\ensuremath{\pi}$ Resonance

Dalitz Plot Analysis of the Decay $D^{+} \to K^{-} π^{+} π^{+}$ and Indication of a Low-Mass Scalar $K π$ Resonance

E. M. Aitala et al. (Fermilab E791 Collaboration)

Phys. Rev. Lett. 89, 121801 – Published 28 August 2002

Abstract

We study the Dalitz plot of the decay $D^{+} \to K^{-} π^{+} π^{+}$ with a sample of 15090 events from Fermilab experiment E791. Modeling the decay amplitude as the coherent sum of known $K π$ resonances and a uniform nonresonant term, we do not obtain an acceptable fit. If we allow the mass and width of the $K_{0}^{*} (1430)$ to float, we obtain values consistent with those from PDG but the $χ^{2}$ per degree of freedom of the fit is still unsatisfactory. A good fit is found when we allow for the presence of an additional scalar resonance, with mass $797 \pm 19 \pm 43 M e V / c^{2}$ and width $410 \pm 43 \pm 87 M e V / c^{2}$ . The mass and width of the $K_{0}^{*} (1430)$ become $1459 \pm 7 \pm 5 M e V / c^{2}$ and $175 \pm 12 \pm 12 M e V / c^{2}$ , respectively. Our results provide new information on the scalar sector in hadron spectroscopy.