Thesis

Since the discovery of the Higgs boson in 2012, the experimental program at the Large Hadron
Collider (LHC) has entered an era of precision measurements, enabling increasingly stringent tests of the
Standard Model (SM). While all measured Higgs boson properties remain consistent with SM predictions, a central parameter of the scalar sector is essentially unconstrained: the Higgs boson self-coupling, ?H.
This parameter governs the shape of the Higgs potential and is intimately connected to the (meta)stability
of the electroweak vacuum and the long-term evolution of the Universe. Its measurement therefore
represents one of the major outstanding challenges of the present and future LHC physics programme.
By combining the exploitation of the full Run-3 dataset with the development of next-generation trigger
algorithms for the HL-LHC, this PhD Thesis Project establishes a direct connection between precision Higgs
measurements and detector innovation. Beyond improving the sensitivity of the current HH ?bbtt analysis,
the project aims to identify and overcome future key experimental limitations, developing new reconstruction
and selection strategies that will contribute to shaping the future CMS physics programme.