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

Abstract

The Compact Linear Collider (CLIC) is a future electron–positron collider that will allow measurements of the trilinear Higgs self-coupling in double Higgs boson events produced at its high-energy stages with collision energies from s = 1.4 to 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 -→ HH νν¯. It is enhanced by including the cross-section measurement of ZHH production at 1.4 TeV. The expected sensitivity of CLIC for Higgs pair production through W-boson fusion is studied for the decay channels b b ¯ b b ¯ and b b ¯ W W ∗ using full detector simulation including all relevant backgrounds at s = 1.4 TeV with an integrated luminosity of L = 2.5 ab- 1 and at s = 3 TeV with L = 5 ab- 1. Combining e +e -→ HH νν¯ and ZHH cross-section measurements at 1.4 TeV with differential measurements in e +e -→ HH νν¯ events at 3 TeV, CLIC will be able to measure the trilinear Higgs self-coupling with a relative uncertainty of - 8 % and + 11 % at 68% C.L., assuming the Standard Model. In addition, prospects for simultaneous constraints on the trilinear Higgs self-coupling and the Higgs-gauge coupling HHWW are derived based on the HH νν¯ measurement.