An amplitude analysis of the $\pi^{0}\pi^{0}$ system produced in radiative $J/\psi$ decays

TL;DR

This paper presents a model-independent amplitude analysis of the $$ system in radiative $J/$ decays, providing detailed scalar and tensor component descriptions based on a large dataset from BESIII.

Contribution

It introduces a minimal-assumption, piecewise function approach to describe the $$ system dynamics, enabling better integration with other phenomenological models.

Findings

Branching fraction of $J/  $ decay measured as $(1.15 \u00b1 0.05) imes 10^{-3}$

Model-independent amplitude description achieved for the $$ system

Analysis based on approximately 1.3 billion $J/$ decays from BESIII

Abstract

An amplitude analysis of the $\pi^{0}\pi^{0}$ system produced in radiative $J/\psi$ decays is presented. In particular, a piecewise function that describes the dynamics of the $\pi^{0}\pi^{0}$ system is determined as a function of $M_{\pi^{0}\pi^{0}}$ from an analysis of the $(1.311\pm0.011)\times10^{9}$ $J/\psi$ decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the $\pi^0\pi^0$ system while making minimal assumptions about the properties or number of poles in the amplitude. Such a model-independent description allows one to integrate these results with other related results from complementary reactions in the development of phenomenological models, which can then be used to directly fit experimental data to obtain parameters of interest. The branching fraction of $J/\psi \to \gamma \pi^{0}\pi^{0}$ is determined to be $(1.15\pm0.05)\times10^{-3}$, where the uncertainty is systematic only and the statistical uncertainty is negligible.