Vector Boson Scattering at the High Luminosity Large Hadron Collider
Physical and Biological Sciences
Senior Thesis
A candidate particle for the Standard Model Higgs Boson has been discovered by the ATLAS and CMS experiments at the Large Hadron Collider (LHC); however, this particle may not be the sole mechanism behind the mass of other particles. This thesis assumes a situation in which there is some unknown physics (at some energy scale $Lambda$) parametrized by an effective theory that not valid for energies much larger than $Lambda$. Proton-proton collisions are considered at a center of mass energy of 14 teraelectronvolts with an average of 140 additional interactions (pileup) per event to determine the discovery potential of the high luminosity-LHC.
Due to the connections between W bosons and the Higgs boson, the scattering of W bosons (which are produced by the incident protons) can provide an invaluable tool to investigating Higgs-related phenomena and is therefore the primary focus of the thesis. Benefits associated to semileptonic WW scattering (a process in which one W decays into a neutrino and a lepton while the other decays into quarks) are addressed as well as challenges associated with event selection in a high pileup environment. A profile likelihood ratio of the invariant mass spectrum resulting from the effective Lagrangian over the Standard Model invariant mass spectrum was used to exclude values of energy scales of unknown Electroweak physics, $Lambda$, above 525 gigaelectronvolts.
