Cross section and Higgs mass measurement with Higgsstrahlung at the CEPC

• Published in: Chinese physics C Vol. 41; no. 2; pp. 33 - 40
• Main Author: 陈振兴 杨迎 阮曼奇 王大勇 李刚 金山 班勇
• Format: Journal Article
• Language: English
• Published: 01.02.2017
• Subjects: Geant4; 希格斯玻色子; 截面; 标准模型; 正负电子对撞机; 矢量玻色子; 统计精度; 质量测量
• ISSN: 1674-1137; 2058-6132; 0254-3052
• DOI: 10.1088/1674-1137/41/2/023003

The Circular Electron Positron Collider（CEPC） is a future Higgs factory proposed by the Chinese high energy physics community. It will operate at a center-of-mass energy of 240–250 Ge V. The CEPC will accumulate an integrated luminosity of 5 ab-1over ten years of operation, producing one million Higgs bosons via the Higgsstrahlung and vector boson fusion processes. This sample allows a percent or even sub-percent level determination of the Higgs boson couplings. With GEANT4-based full simulation and a dedicated fast simulation tool, we have evaluated the statistical precisions of the Higgstrahlung cross section σZH and the Higgs mass m H measurement at the CEPC in the Z →μ~＋μ~-channel. The statistical precision of σZH（m_H） measurement could reach 0.97%（6.9 MeV） in the model-independent analysis which uses only the information from Z boson decays. For the standard model Higgs boson, the m H precision could be improved to 5.4 Me V by including the information from Higgs decays. The impact of the TPC size on these measurements is investigated. In addition, we studied the prospect of measuring the Higgs boson decaying into invisible final states at the CEPC. With the Standard Model ZH production rate, the upper limit of B（H → inv.） could reach 1.2% at 95% confidence level.