Phenomenology of the trilinear Higgs coupling at proton-proton colliders

We investigate Higgs pair production at proton-proton colliders, with emphasis on the gluon fusion channel at the HL-LHC. We study the behaviour of the leading order matrix element using exact computation of quark loops and infinite quark mass approximation. We analyse di-Higgs kinematics in search for phase space regions where the contribution of Higgs self-coupling to SM Higgs pair production is enhanced. We discuss how non-SM values of the Higgs trilinear coupling may affect the kinematics of the Higgs pair.