The $K^-\pi^+$ S-wave from the $D^+ \to K^-\pi^+\pi^+$ decay

TL;DR

This paper presents a model-independent analysis of the $K^-\pi^+$ S-wave amplitude in $D^+ o K^-\pi^+\pi^+$ decays using Fermilab data, providing direct insights into the S-wave behavior across the elastic range.

Contribution

It introduces a model-independent method to determine the $K^-\pi^+$ S-wave amplitude directly from decay data, enhancing understanding of meson interactions.

Findings

S-wave amplitude measured across the entire elastic range.

S-wave described as a complex function directly from data.

P- and D-waves modeled with Breit-Wigner amplitudes.

Abstract

Using data from FOCUS (E831) experiment at Fermilab, we present a model independent partial-wave analysis of the $K^-\pi^+$ S-wave amplitude from the decay $D^+ \to K^-\pi^+\pi^+$. The S-wave is a generic complex function to be determined directly from the data fit. The P- and D-waves are parameterized by a sum of Breit-Wigner amplitudes. The measurement of the S-wave amplitude covers the whole elastic range of the $K^-\pi^+$ system.