Measuring Hadronic Higgs Boson Branching Ratios at Future Lepton Colliders

Abstract

We present a novel strategy for the simultaneous measurement of Higgs-boson branching ratios into gluons and light quarks at a future lepton collider operating in the Higgs-factory mode. Our method is based on template fits to global event-shape observables, and in particular fractional energy correlations, thereby exploiting differences in the QCD radiation patterns of quarks and gluons. In a constrained fit of the deviations of the light-flavour hadronic Higgs-boson branching ratios from their Standard Model expectations, based on an integrated luminosity of $5{\text{ab}}^{-1}$, we obtain $68\%$ confidence level limits of $\hat{I}{¼}_{gg}=1\pm 0.05$ and $\hat{I}{¼}_{q\bar{q}}<21$.

14 pages, 7 figures, 2 tables, revised results and plots