A Handy Tool for History Keeping of Geant4 Tracks and its Application to Studies of Fundamental Limits on PFA Performance

It is widely recognized that good jet energy resolution is one of the most important requirements to the detectors for the future linear $e^+e^-$ collider experiments. The Particle Flow Analysis (PFA) is currently under intense studies as the most promising way to achieving the best attainable resolution. In order to clarify the fundamental limits on the jet energy resolution with the PFA, we have developed a set of C++ classes that facilitates history keeping of particle tracks within the framework of Geant4. In this paper this software tool is described and applied to a generic detector model so as to identify fundamental limiting factors to the PFA performance.