A Non-parametric Approach to Measuring the \kpi{} Amplitudes in \dpkkpi{} Decay

TL;DR

This paper introduces a novel non-parametric method to analyze \\kpi{} amplitudes in \\dpkkpi{} decay, revealing a broader S-wave contribution and potential new D-wave component, improving understanding of decay dynamics.

Contribution

The paper presents the first non-parametric analysis of \\kpi{} amplitudes in \\dpkkpi{} decay, offering new insights beyond traditional parametric models.

Findings

Wider S-wave contribution than PDG Breit-Wigner model

Some evidence for a new D-wave component at low \\kpi{} mass

Results are roughly consistent with previous measurements

Abstract

Using a large sample of \dpkkpi{} decays collected by the FOCUS photoproduction experiment at Fermilab, we present the first non-parametric analysis of the \kpi{} amplitudes in \dpkkpi{} decay. The technique is similar to the technique used for our non-parametric measurements of the \krzmndk{} form factors. Although these results are in rough agreement with those of E687, we observe a wider S-wave contribution for the \ksw{} contribution than the standard, PDG \cite{pdg} Breit-Wigner parameterization. We have some weaker evidence for the existence of a new, D-wave component at low values of the $K^- \pi^+$ mass.