The Higgs→ b b ¯ $$ b\overline{b} $$ , c c ¯ $$ c\overline{c} $$ , gg measurement at CEPC

Abstract

Abstract Accurately measuring the properties of the Higgs boson is one of the core physics objectives of the Circular Electron Positron Collider (CEPC). As a Higgs factory, the CEPC is expected to operate at a centre-of-mass energy of 240 GeV, deliver an integrated luminosity of 5.6 ab −1, and produce one million Higgs bosons according to the CEPC Conceptual Design Report (CDR). Combining measurements of the ℓ + ℓ − H, ν ν ¯ H $$ \nu \overline{\nu}H $$ , and q q ¯ H $$ q\overline{q}H $$ channels, we conclude that the signal strength of H → b b ¯ / c c ¯ / gg $$ H\to b\overline{b}/c\overline{c}/ gg $$ can be measured with a relative accuracy (relative statistical uncertainty only) of 0.27%/4.03%/1.56%. Extrapolating to the recently released TDR operating parameters corresponding to the integrated luminosity of 20 ab −1, the relative accuracy of H → b b ¯ / c c ¯ / gg $$ H\to b\overline{b}/c\overline{c}/ gg $$ signal strength is 0.14%/2.13%/0.82% (relative statistical uncertainty only). We analyze the dependence of the expected accuracies on the critical detector performances: Color Singlet Identification (CSI) for the q q ¯ H $$ q\overline{q}H $$ channel and flavor tagging for both ν ν ¯ H $$ \nu \overline{\nu}H $$ and q q ¯ H $$ q\overline{q}H $$ channels. Compared to the baseline CEPC detector performance, ideal flavor tagging can increase the H → b b ¯ / c c ¯ / gg $$ H\to b\overline{b}/c\overline{c}/ gg $$ signal strength accuracy by 2%/63%/13% in the ν ν ¯ H $$ \nu \overline{\nu}H $$ channel and 35%/122%/181% in the q q ¯ H $$ q\overline{q}H $$ channel. A strong dependence between the CSI performance and anticipated accuracies in q q ¯ H $$ q\overline{q}H $$ channel is identified. The relevant systematic uncertainties are also discussed in this paper.

Keywords

• e+-e- Experiments
• Higgs Physics
• Jets