Probing light-quark Yukawa couplings via hadronic event shapes at lepton colliders

Understand

We propose a novel idea for probing the Higgs boson couplings through the measurement of hadronic event shape distributions in the decay of the Higgs boson at lepton colliders.

• The method provides a unique test of the Higgs boson couplings and of QCD effects in the decay of the Higgs boson.
• It can be used to probe the Yukawa couplings of the light quarks and to further test the mechanism of electroweak symmetry breaking.
• From a case study for the proposed Circular Electron-Positron Collider, assuming a hypothesis of SM-like theory, light-quark couplings with a strength greater than 9% of the bottom-quark Yukawa coupling in the standard model can be excluded.