Search for Higgs Boson and Observation of 𝑍 Boson through Their Decay into a Charm Quark-Antiquark Pair in Boosted Topologies in Proton-Proton Collisions at √𝑠=13 TeV

A search for the standard model (SM) Higgs boson ( H ) produced with transverse momentum ( p T ) greater than 450 GeV and decaying to a charm quark-antiquark ( c c ¯ ) pair is presented. The search is performed using proton-proton collision data collected at s = 13 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb - 1 . Boosted H → c c ¯ decay products are reconstructed as a single large-radius jet and identified using a deep neural network charm tagging technique. The method is validated by measuring the Z → c c ¯ decay process, which is observed in association with jets at high p T for the first time with a signal strength of 1.00 - 0.14 + 0.17 ( syst ) ± 0.08 ( theo ) ± 0.06 ( stat ) , defined as the ratio of the observed process rate to the SM expectation. The observed (expected) upper limit on σ ( H ) B ( H → c c ¯ ) is set at 47 (39) times the SM prediction at 95% confidence level.