Precision study of K^\pm\to\pi^\pm\pi^0\pi^0 and K^\pm\to\pi^\pm\pi^+\pi^- Dalitz plot distributions by NA48/2

TL;DR

This paper presents a detailed analysis of $K^ o3$ decays using high-statistics data from NA48/2, revealing pion rescattering effects and precise Dalitz plot parameters, advancing understanding of low-energy QCD interactions.

Contribution

It provides the first detailed Dalitz plot analysis of $K^ o$ decays with unprecedented precision, extracting $$ scattering lengths and decay slope parameters.

Findings

Observation of pion rescattering effects in Dalitz plots.

Precise measurement of Dalitz plot slope parameters.

Extraction of $$ scattering lengths from decay data.

Abstract

The NA48/2 experiment at the CERN SPS has collected an unprecedented sample of $K^\pm\to3\pi$ decays. The high statistics and the good resolution of the detectors allow a unique investigation of the detailed phase space distributions of these decays. The effects of final state pion rescattering observed in the Dalitz plot distribution of the $K^\pm\to\pi^\pm\pi^0\pi^0$ decays turned out to be a powerful tool for extraction of the S-wave $\pi\pi$ scattering lengths. The large statistics also allowed a precise measurement of the Dalitz plot slope parameters for the $K^\pm\to3\pi^\pm$ decays.