The Higgs→ $$ b\overline{b} $$, $$ c\overline{c} $$, 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, $$ \nu \overline{\nu}H $$ ν ν ¯ H , and $$ q\overline{q}H $$ q q ¯ H channels, we conclude that the signal strength of $$ H\to b\overline{b}/c\overline{c}/ gg $$ H → b b ¯ / c 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 $$ H\to b\overline{b}/c\overline{c}/ gg $$ H → b b ¯ / c 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 $$ q\overline{q}H $$ q q ¯ H channel and flavor tagging for both $$ \nu \overline{\nu}H $$ ν ν ¯ H and $$ q\overline{q}H $$ q q ¯ H channels. Compared to the baseline CEPC detector performance, ideal flavor tagging can increase the $$ H\to b\overline{b}/c\overline{c}/ gg $$ H → b b ¯ / c c ¯ / gg signal strength accuracy by 2%/63%/13% in the $$ \nu \overline{\nu}H $$ ν ν ¯ H channel and 35%/122%/181% in the $$ q\overline{q}H $$ q q ¯ H channel. A strong dependence between the CSI performance and anticipated accuracies in $$ q\overline{q}H $$ q q ¯ H channel is identified. The relevant systematic uncertainties are also discussed in this paper.