Search for ZZ and ZH production in the bbb¯ ¯b final state using proton-proton collisions at √s = 13 TeV

Abstract

A search for ZZ and ZH production in the bbb¯ b¯ final state is presented, where H is the standard model (SM) Higgs boson. The search uses an event sample of protonproton collisions corresponding to an integrated luminosity of 133 fb−1 collected at a center-of-mass energy of 13 TeV with the CMS detector at the CERN LHC. The analysis introduces several novel techniques for deriving and validating a multi-dimensional background model based on control samples in data. A multiclass multivariate classifier customized for the bbb¯ b final state is developed to derive the background ¯ model and extract the signal. The data are found to be consistent, within uncertainties, with the SM predictions. The observed (expected) upper limits at 95% confidence level are found to be 3.8 (3.8) and 5.0 (2.9) times the SM prediction for the ZZ and ZH production cross sections, respectively.