Search for the Standard Model Higgs boson produced in association with top quarks in the lepton plus jets channel

Results for the search of a Higgs boson decaying to a bottom quark-antiquark pair produced with a top quark-antiquark pair (t$\bar{t}$H) in the lepton plus jets channel in proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV are presented. The data used corresponds to an integrated luminosity of 12.9 fb$^{-1}$ recorded with the CMS experiment in 2016. To increase the sensitivity of the search, selected events are categorized by number of jets and number of b-tagged jets resulting in different expected signal and background rates. For each category two multivariate techniques are combined to separate the signal and back- ground events. A machine learning process called a boosted decision tree (BDT) is trained on the two types of classes of events and then split into high and low purity based on the output. The physics motivated matrix element method (MEM) is applied to the BDT out- put to obtain the final two dimensional discriminator. The result is presented in terms of the t$\bar{t}$H signal strength modifier µ, the ratio of the observed t$\bar{t}$H production cross section relative to the expected cross section based on a 125 GeV Standard Model Higgs boson. A combined fit of the final discriminant in all categories of the lepton plus jets channel results an observed (expected) upper limit of µ < 1.8(2.1$_{-0.6}^{+1.0}$) at the 95% confdience level. The -0.6 best-fit value of the signal strength modifier is found to be -0.43$_{-1.02}^{+1.02}$.