Requirement analysis for dE/dx measurement and PID performance at the CEPC baseline detector

Abstract

The Circular Electron-Positron Collider (CEPC) can be operated not only as a Higgs factory but also as a Z-boson factory, offering great opportunities for flavor physics studies where Particle Identification (PID) is critical. The baseline detector of the CEPC could record TOF and dE/dx information that can be used to distinguish particles of different species. We quantify the physics requirements and detector performance using physics benchmark analyzes with full simulation. We conclude that at the benchmark TOF performance of 50ps, the dE/dx resolution should be better than 3% for incident particles in the barrel region with a relevant momentum larger than 2GeV/c. This performance leads to an efficiency/purity for K± identification of 97%/96%, for D0→π+K− reconstruction of 68.19%/89.05%, and for ϕ→K+K− reconstruction of 82.26%/77.70%, providing solid support for relevant CEPC flavor physics measurements.