The H → bb̄ , cc̄ , gg measurement at CEPC

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 5600 fb−1, and produce one million Higgs bosons. Combining the measurements of the `+`−H, νν̄H, and qq̄H channels, we conclude that the signal strength ofH → bb̄/cc̄/gg can be measured with a relative accuracy of 0.27%/3.82%/1.52%. We analyze the dependence of the expected accuracies on the critical detector performances: Color Singlet Identification (CSI) for the qq̄H channel and flavor tagging for both νν̄H and qq̄H channels. We observe that compared to the baseline CEPC detector performance, the ideal flavor tagging increases the accuracy of the H → bb̄/cc̄/gg signal strength by 2%/52%/10% in the νν̄H channel and 35%/107%/169% in the qq̄H channel. A CSI variable using the truth level information could improve the signal-to-background ratio by almost an order of magnitude in the qq̄H channel, resulting in an improvement of 6%/65%/82% for the accuracy of the qq̄H(H → bb̄/cc̄/gg) signal strength. Also at Some University. Also at Some University. Corresponding author. ar X iv :2 20 3. 01 46 9v 1 [ he pex ] 3 M ar 2 02 2