Measurements of WH and ZH Production with Higgs Boson Decays into Bottom Quarks and Direct Constraints on the Charm Yukawa Coupling in 13 TeV pp Collisions with the ATLAS Detector

Abstract

A study of the Higgs boson decaying into bottom quarks (H -> b (b) over bar) and charm quarks (H -> c (c) over bar) is performed, in the associated production channel of the Higgs boson with a W or Z boson, using 140 fb(-1) of proton-proton collision data at root s = 13 TeV collected by the ATLAS detector. The individual production of WH and ZH with H -> b (b) over bar is established with observed (expected) significances of 5.3 (5.5) and 4.9 (5.6) standard deviations, respectively. Differential cross-section measurements of the gauge boson transverse momentum within the simplified template cross-section framework are performed in a total of 13 kinematical fiducial regions. The search for the H -> c (c) over bar decay yields an observed (expected) upper limit at 95% confidence level of 11.5 (10.6) times the Standard Model prediction. The results are also used to set constraints on the charm coupling modifier, resulting in vertical bar kappa(c)vertical bar < 4.2 at 95% confidence level. Combining the H -> b<(b)over bar> and H -> c (c) over bar measurements constrains the absolute value of the ratio of Higgs-charm and Higgs-bottom coupling modifiers (vertical bar kappa(c)/kappa(b)vertical bar) to be less than 3.6 at 95% confidence level.