UC San Diego

This dissertation presents a search for anomalous production of the Higgs boson with the Compact Muon Solenoid (CMS) experiment, together with two developments in reconstruction and computing for the High-Luminosity LHC (HL-LHC). The search targets vector boson scattering production of a Higgs boson with two vector bosons. It aims to constrain the quartic HHVV coupling, quoted relative to its Standard Model value: departures from unity grow the cross section quadratically and boost the final-state bosons. The search uses the full Run 2 dataset, 138 inverse femtobarns at a center-of mass energy of 13 TeV and 283 inverse femtobarns of Run 3 data at 13.6 TeV, in three channels: an all-hadronic state with three large-radius jets and two single-lepton states. The dominant multijet and top quark backgrounds are estimated from data with an ABCD method built on two decorrelated classifiers, and the signal is extracted from a simultaneous fit to several orthogonal signal regions per channel. The combination excludes a coupling of 1.5, with an observed 95 percent confidence level upper limit of 0.48 on that rate against an expectation of 0.64; the Run 3 data alone constrain the coupling between 0.612 and 1.387, improving on the published Run 2 result. The second development addresses charged-particle tracking at the HL-LHC using a machine learning approach: the first demonstration in CMS of a transformer-based model trained with object condensation, built on Line Segment Tracking triplets to reconstruct full track candidates. The model reduces the fake rate by roughly a factor of three and all but eliminates duplicates, at an efficiency comparable to the algorithmic baseline. The third concerns moving the resulting data. The HL-LHC will produce an unprecedented volume of data, so the wide-area network is no longer a best-effort service but a critical resource that must be managed. This work integrates the Rucio data management system with the SENSE software-defined networking service, so that bandwidth is allocated by transfer priority and reservations can be reconfigured mid-transfer without interrupting traffic in flight. It is demonstrated on a multi-domain testbed and in benchmarks at 400 Gbps.