Measurements of the Dalitz Plot Parameters for $K^{\pm}\to\pi^{\pm}\pi^0\pi^0$ Decays

TL;DR

This paper reports precise measurements of Dalitz plot parameters for charged kaon decays into three pions, revealing the influence of charge exchange scattering near the pion pair mass threshold and comparing results with prior studies.

Contribution

First measurement of Dalitz plot parameters for $K^{\pm} o \pi^{\pm}\pi^{0}\pi^{0}$ decays at 35 GeV/c, highlighting the role of charge exchange scattering effects.

Findings

Parameters depend on the $\pi^0\pi^0$ mass cut.

Data indicates significant charge exchange scattering effects.

Comparison with previous measurements shows consistency and new insights.

Abstract

The $g$, $h$, and $k$ Dalitz plot parameters, which are coefficients in a series expansion of the squared module of the matrix element $|M(u,v)|^{2} \propto 1 + gu + hu^{2} + kv^{2}$ ($u$, $v$ are invariant variables), have been measured for $K^{\pm}\to \pi^{\pm} \pi^{0} \pi^{0}$ decays using $35 GeV/c$ hadron beams at the IHEP (Protvino) accelerator. Dependences of parameters and fit quality on the $\pi^0\pi^0$ mass cut were investigated. The results point to the important role of $\pi^+\pi^- \to \pi^0\pi^0$ charge exchange scattering near the $\pi^0\pi^0$ mass threshold. The comparison of our data with previous measurements is presented.