Probe Higgs boson pair production via the $3\ell 2j$ + missing $E_T$ mode

Abstract

We perform a detailed hadron-level study on the sensitivity of Higgs boson pair production via the $W{W}^{\ast }W{W}^{\ast }$ channel with the final state $3\ell 2j$ + missing $E_T$ at the LHC with the collision energy $\sqrt{S}=14$ TeV and a future 100 TeV collider. To avoid the huge background from $pp\to ZW+\text{jets}$ processes, we confine to consider the four lepton patterns: $e^{\pm }{e}^{\pm }{\mu }^{\mp }$ and ${\mu }^{\pm }{\mu }^{\pm }{e}^{\mp }$. We propose a partial reconstruction method to determine the most reliable combination. After that, we examine a few crucial observables which can discriminate efficiently signal and background events, especially we notice that the observable $m_{T2}$ is very efficient. For the LHC 14 TeV collisions, with an accumulated 3000 fb${}^{-1}$ dataset, we find that the sensitivity of this mode can reach up to 1.5 $\sigma$ for the Standard Model and the triple coupling of Higgs boson ${\lambda }_3$ in the simplest effective theory can be constrained into the range [-1, 8] at $95\%$ confidence level; at a 100 TeV collider with the integrated luminosity 3000 fb${}^{-1}$, the sensitivity can reach up to 13 $\sigma$ for the Standard Model and we find that all values of ${\lambda }_3$ in the effective theory can be covered up to 3$\sigma$ even without optimising signals. To precisely measure the triple coupling of Higgs boson ${\lambda }_3=1$ of the Standard Model at a 100 TeV collider, by using the invariant mass of three leptons which is robust to against the contamination of underlying events and pileup effects and by performing a ${\chi }^2$ analysis, we find that it can be determined into a range [0.8, 1.5] at $95\%$ confidence level.

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