The Compact Linear Collider (CLIC) is an option for a future collider operating at centre-of-mass energies up to , providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages: , 1.4 and . The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung () and -fusion (), resulting in precise measurements of the production cross sections, the Higgs total decay width , and model-independent determinations of the Higgs couplings. Operation at provides high-statistics samples of Higgs bosons produced through -fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes and allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit.

Open Access, Copyright CERN, for the benefit of the CLICdp Collaboration. Article funded by SCOAP 3 .

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Top quark production in the process e + e − → tt at a future linear electron positron collider with polarised beams is a powerful tool to determine indirectly the scale of new physics. The presented study, based on a detailed simulation of the ILD detector concept, assumes a centre-of-mass energy of √ s = 500 GeV and a luminosity of L = 500 fb −1 equally shared between the incoming beam polarisations of P e − , P e + = ±0.8, ∓0.3. Events are selected in which the top pair decays semi-leptonically and the cross sections and the forward-backward asymmetries are determined. Based on these results, the vector, axial vector and tensorial C P conserving couplings are extracted separately for the photon and the Z 0 component. With the expected precision, a large number of models in which the top quark acts as a messenger to new physics can be distinguished with many standard deviations. This will dramatically improve expectations from e.g. the LHC for electro-weak couplings of the top quark.