Constraint on the total width of the Higgs boson from Higgs boson and four-top-quark measurements in 𝑝�𝑝� collisions at √𝑠� = 13 TeV with the ATLAS detector

Abstract

This Letter presents a constraint on the total width of the Higgs boson (Γ𝐻) using a combined measurement ofon-shell Higgs boson production and the production of four top quarks, which involves contributions from offshellHiggs boson-mediated processes. This method relies on the assumption that the tree-level Higgs-top Yukawacoupling strength is the same for on-shell and off-shell Higgs boson production processes, thereby avoiding anyassumptions about the relationship between on-shell and off-shell gluon fusion Higgs production rates, whichwere central to previous measurements. The result is based on up to 140 fb-1 of proton-proton collisions at acentre-of-mass energy ofSQUARE ROOT𝑠 = 13 TeV collected with the ATLAS detector at the Large Hadron Collider. Theobserved (expected) 95% cofidencelevel upper limit on Γ𝐻 is 450 MeV (75 MeV). Additionally, consideringthe constraint on the Higgs-top Yukawa coupling from loop-induced Higgs boson production and decay processesfurther yields an observed (expected) upper limit of 160 MeV (55 MeV).