Search for Higgs boson decay to a charm quark-antiquark pair in proton-proton collisions at $\sqrt{s}$ = 13 TeV

CERN-LHC. Search for Higgs boson decay to a charm quark-antiquark pair in proton-proton collisions at sqrt(s) = 13 TeV.

A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H → cc¯,
produced in association with a leptonically decaying V (W or Z) boson is presented. The search is
performed with proton-proton collisions at ffiffi
s p ¼ 13 TeV collected by the CMS experiment, corresponding
to an integrated luminosity of 138 fb−1. Novel charm jet identification and analysis methods using machine
learning techniques are employed. The analysis is validated by searching for Z → cc¯ in VZ events, leading
to its first observation at a hadron collider with a significance of 5.7 standard deviations. The observed
(expected) upper limit on σðVHÞBðH → cc¯Þ is 0.94 (0.50þ0.22 −0.15 )pb at 95% confidence level (C.L.),
corresponding to 14 (7.6þ3.4 −2.3 ) times the standard model prediction. For the Higgs-charm Yukawa coupling
modifier, κc, the observed (expected) 95% C.L. interval is 1.1 < jκcj < 5.5 (jκcj < 3.4), the most stringent
constraint to date.