Search for heavy resonances decaying to a pair of Higgs bosons in four b quark final state in $pp$ collisions at $\sqrt{s} = 13 TeV$ using the CMS detector at the LHC

The search for heavy resonances (i.e. Kaluza-Klein Bulk Graviton and Radion)decaying to a pair of standard model Higgs bosons is presented. Both Higgsbosons decay further to b quark-antiquark pairs as the final state. The data usedfor this analysis were from the proton-proton collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 2.7 fb−1 and werecollected by the CMS detector during the Run-II of the LHC in 2015. These resonance particles have masses that are ≥ 1 TeV, thus the Higgs bosons are highlyLorentz-boosted and each H → b¯ can be reconstructed as one hadronic jet. Abnew tagging algorithm called "double-b tagger" is used to identify the b¯ pairsbinside the Higgs jet. The "Alphabet" method is used to estimate the background.The predicted background shows good agreement with the data and no significant data excess was observed. The results are then interpreted in terms of 95%CLs upper limit on the production cross section of the resonances. No exclusionwas made on both Bulk Graviton and Radion mass between 1000 to 4500 GeV.A larger data sample is needed to exclude from the given mass range for theassumed WED model parameter.Thesis Supervisor: Shin-Shan Eiko YuTitle: Associate Professor