Inclusive search for a boosted Higgs boson decaying to a charm quark pairs in proton-proton collisions at sqrt(s) = 13 TeV

A search for the standard model Higgs ($\text{H}$) boson produced with transverse momentum greater than $450~\text{GeV}$ and decaying to charm quark-antiquark pairs ($\text{c}\bar{\text{c}}$) is performed using proton-proton collision data collected by the CMS experiment at the LHC at $\sqrt{s}=13~\text{TeV}$. The data sample corresponds to an integrated luminosity of $138\,\text{fb}^{-1}$. The search is inclusive in $\text{H}$ production mode. Highly Lorentz-boosted $\text{H}$ decaying to $\text{c}\bar{\text{c}}$ are reconstructed as single large-radius jets, and are identified using a dedicated charm tagging technique based on a deep neural network. The method is validated with the $\text{Z}\to \text{c}\bar{\text{c}}$ decay process, which is observed for the first time in the $\text{Z}$+jets production mode at a hadron collider with a significance of well over 5 standard deviations and a signal strength of $0.91_{-0.15}^{+0.18}\text{(exp.)}\pm0.7\text{(th.)}\pm0.05\text{(stat.)}$ relative to the standard model prediction. A 95\% confidence level observed (expected) upper limit is set on the $\text{H}\to \text{c}\bar{\text{c}}$ signal strength of 45 (38) times the standard model prediction.