摘要
We perform the most up-To-date comprehensive signal-background analysis for Higgs-pair production in HH→bbγγ channel at the HL-LHC and HL-100 TeV hadron collider, with the goal of probing the self-coupling λ3H of the Higgs boson which is normalized to its standard-model value of 1. We simulate all the standard-model signal and background processes and emphasize that the ggH(→γγ) background has been overlooked in previous studies. We find that, even for the most promising channel HH→bbγγ at the HL-LHC with a luminosity of 3000 fb-1, the significance is still not high enough to establish the Higgs self-coupling at the standard-model (SM) value. Instead, we can only constrain the self-coupling to-1.0<λ3H<7.6 at 95% confidence level after considering the uncertainties associated with the top-Yukawa coupling and the estimation of backgrounds. Here we also extend the study to the HL-100 TeV hadron collider. With a luminosity of 3 ab-1, we find there exists a bulk region of 2.6λ3H4.8 in which one cannot pin down the trilinear coupling. Otherwise, one can measure the coupling with a high precision. At the SM value, for example, we show that the coupling can be measured with about 20% accuracy. While assuming 30 ab-1, the bulk region reduces to 3.1λ3H4.3, and the trilinear coupling can be measured with about 7% accuracy at the SM value.