Prospects of non-resonant di-Higgs searches and Higgs boson self-coupling measurement at the HE-LHC using machine learning techniques

The prospects of observing the non-resonant di-Higgs production in the Standard Model at the proposed high energy upgrade of the LHC, $viz.$ the HE-LHC$~$($sqrt{s}=27~{rm TeV}$ and $mathcal{L} = 15~{rm ab^{-1}}$) is studied. Various di-Higgs final states are considered based on their cleanliness and signal yields. The search for the non-resonant double Higgs production at the HE-LHC is performed in the $bbar{b}gammagamma$, $bbar{b}tau^{+}tau^{-}$, $bbar{b}WW^{*}$, $WW^{*}gammagamma$, $bbar{b}ZZ^{*}$ and $bbar{b}mu^{+}mu^{-}$ channels. The signal-background discrimination is performed through multivariate analyses using the Boosted Decision Tree Decorrelated$~$(BDTD) algorithm in the$~$TMVA framework, the XGBoost toolkit and Deep Neural Network$~$(DNN). The variation in the kinematics of Higgs pair production as a function of the self-coupling of the Higgs boson, $lambda_{h}$, is also studied. The ramifications of varying $lambda_{h}$ on the $bbar{b}gammagamma$, $bbar{b}tau^{+}tau^{-}$ and $bbar{b}WW^{*}$ search analyses optimized for the SM hypothesis is also explored.