Double Higgs boson production and Higgs self-coupling extraction at CLIC

The Compact Linear Collider (CLIC) is a future electron-positron collider that will allow measurement of the trilinear Higgs self-coupling in double Higgs boson events produced at its high-energy stages with collision energies of √s = 1.5 and 3 TeV. The sensitivity to the Higgs self-coupling is driven by the measurements of the cross section and the invariant mass distribution of the Higgs-boson pair in the W-boson fusion process, e+e− → HHνeνe. It is enhanced by including the cross-section measurement of ZHH production at 1.5 TeV. The expected sensitivity of CLIC for Higgs pair production through W-boson fusion is studied for the decay channels bbbb and bbWW∗ using full detector simulation including all relevant backgrounds. With an integrated luminosity of L = 5 ab−1 at √s = 3 TeV, CLIC will be able to measure the trilinear Higgs self-coupling with a relative uncertainty of −7 % and +11 % at 68 % C.L., assuming the Standard Model.