Electron Yukawa coupling via s-channel e+e− → H production at the Higgs pole

Abstract

Measuring the electron Yukawa is impossible in Higgs boson decays, H → e+e−, given the smallness of the electron mass that leads to a negligible decay branching ratio. The only direct method to extract it is through resonant s-channel production in e+e− collisions running at (exactly) the Higgs pole mass. Such a measurement requires monochromatization of the beams leading to a centre-of-mass energy spread not much larger than the Higgs boson width δ√s ≈ Γ_H = 4.2 MeV, as well as an accurate and precise knowledge of the Higgs boson mass, within MeV uncertainties. A preliminary study, combining 10 different Higgs decay modes, indicates that a 0.7σ significance above the (much larger) backgrounds can be reached for every 10 ab⁻¹ integrated at the FCC-ee [1]. An update of the analysis, using the latest developments in machine-learning tools, will be carried out in order to further suppress backgrounds, and determine the precision on the electron Yukawa coupling ultimately reachable.

• [1] Higgs physics at the Future Circular Collider D. d’Enterria
• The Snowmass LOI: Monochromatized direct s-channel Higgs production in e+e- at √s=125 GeV

Contact

David d’Enterria

Bibliography

• EPJ+ essay, Measuring the electron Yukawa coupling via resonant s-channel Higgs production at FCC-ee D. d’Enterria et al, July 2021
• EPJ+, The challenge of monochromatization A. Faus-Golfe et al, Dec. 2021

Talks

• The Snowmass/EF01 meeting devoted to ee -> H, 2 Sep, 2020
• s-channel ee->H discussion meeting Nov 25, 2020