Dimension-six electroweak top-loop effects in Higgs production and decay

AbstractWe study the next-to-leading order electroweak corrections to Higgs processes from dimension-six top-quark operators in the Standard Model Effective Field Theory approach. We consider the major production channels, includingW H,ZH, and VBF production at the LHC, andZH, VBF production at future lepton colliders, as well as the major decay channels includingH→ γγ,γZ, W lν, Zll,$$ b\overline{b} $$bb¯, μμ, ττ. The results show that within the current constraints, top-quark operators can shift the signal strength of the loop-induced processes, i.e.H→ γγ,γZ, by factors of$$ \sim \mathcal{O}(1)-\mathcal{O}(10) $$∼O1−O10, and that of the tree-level processes, i.e. all remaining production and decay channels, by ∼ 5 − 10% at the LHC, and up to ∼ 15% at future lepton colliders. This implies that essentially all Higgs channels have started to become sensitive to top-quark couplings, and in particular, Higgs observables at high luminosity LHC as well as future lepton colliders, even below the$$ t\overline{t} $$tt¯threshold, will improve our knowledge of top-quark couplings. We derive the sensitivities of Higgs measurements to top-quark operators at the high luminosity LHC, using projections for both inclusive and differential measurements. We conclude that treating the dimension-six top-quark sector and the Higgs/electroweak sector separately may not continue to be a good strategy. A global analysis combining Higgs and top-quark measurements is desirable, and our calculation and implementation provide an automatic and realistic simulation tool for this purpose.