Study of $D^{+} \to K^{-} \pi^+ e^+ \nu_e$

TL;DR

This paper reports a detailed analysis of the decay D+ to K- pi+ e+ nu_e, measuring branching fractions, resonance parameters, and form factors, providing new insights into the decay dynamics and resonance contributions.

Contribution

It introduces a comprehensive measurement of branching fractions, resonance parameters, and form factors for the decay D+ to K- pi+ e+ nu_e, including a partial wave analysis and model-independent form factor measurements.

Findings

Branching fraction for D+ to K- pi+ e+ nu_e is (3.71 ± 0.03 ± 0.08)%

S-wave contribution accounts for about 6% of the decay rate

Parameters of the K*(892) resonance and form factors are measured

Abstract

We present an analysis of the decay $D^{+} \to K^{-} \pi^+ e^+ \nu_e$ based on data collected by the BESIII experiment at the $\psi(3770)$ resonance. Using a nearly background-free sample of 18262 events, we measure the branching fraction $\mathcal{B}(D^{+} \to K^{-} \pi^+ e^+ \nu_e) = (3.71 \pm 0.03 \pm 0.08)\%$. For $0.8<m_{K\pi}<1.0$ GeV/$c^{2}$ the partial branching fraction is $\mathcal{B}(D^{+} \to K^{-} \pi^+ e^+ \nu_e)_{[0.8,1]} = (3.33 \pm 0.03 \pm 0.07)\%$. A partial wave analysis shows that the dominant $\bar K^{*}(892)^{0}$ component is accompanied by an \emph{S}-wave contribution accounting for $(6.05\pm0.22\pm0.18)\%$ of the total rate and that other components are negligible. The parameters of the $\bar K^{*}(892)^{0}$ resonance and of the form factors based on the spectroscopic pole dominance predictions are also measured. We also present a measurement of the $\bar K^{*}(892)^{0}$ helicity basis form factors in a model-independent way.