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

TL;DR

This paper evaluates the particle identification capabilities of the CEPC baseline detector, focusing on dE/dx and TOF measurements, to ensure effective flavor physics studies with high efficiency and purity.

Contribution

It provides a detailed analysis of the required detector performance parameters, including dE/dx resolution and TOF timing, for successful particle identification at CEPC.

Findings

dE/dx resolution should be better than 3% for particles above 2 GeV/c

Achieved particle ID efficiencies: 97% for K±, 68.19% for D0→π+K−, 82.26% for φ→K+K−

High purity levels support CEPC flavor physics measurements

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 $50\,$ps, the dE/dx resolution should be better than 3% for incident particles in the barrel region with a relevant energy larger than $2\, $GeV/c. This performance leads to an efficiency/purity of $K^{\pm}$ identification 97%/96%, $D^0\to \pi^+K^-$ reconstruction 68.19%/89.05%, and $\phi\to K^+K^-$ reconstruction 82.26%/77.70%, providing solid support for relevant CEPC flavor physics measurements.