Search for a new resonance in the boosted di-Higgs to 4 bottom quarks final state at √s = 8 TeV using the ATLAS detector at the Large Hadron Collider

This thesis presents a search for a new, heavy particle decaying to a pair of Higgs bosons in the 4 bottom quarks final state at √s= 8 TeV using the ATLAS detector at the Large Hadron Collider. The full data collected by ATLAS in 2012 at √s = 8 TeV is used, corresponding to a total luminosity of 19.5 fb -1. A novel technique, using smaller radius track jet to tag bottom quarks in combination with two large radius calorimeter jets to fully reconstruct boosted event topologies, significantly improves the sensitivity up to the mass scale of 2 TeV. In the absence of an excess, upper limits on the production cross section are set with 95% confidence level, using Kaluza-Klein gravitons in the bulk Randall-Sundrum model with coupling c ≡ k √M pl = 1.0 and 2.0 as benchmarks.