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Experimental Particle and Astro-Particle Physics Seminar
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Europe/Zurich
Description
Abstract:
Triple-Higgs production is one of the most ambitious targets of the LHC Higgs program. As the first process with direct sensitivity to the quartic Higgs self-coupling, and complementary sensitivity to the trilinear coupling, HHH production provides a unique probe of the Higgs potential. In the Standard Model its rate is extremely small, but it can be significantly enhanced in several extensions of the Higgs sector, making it both a precision and discovery-oriented target.
In this seminar, I will review the emerging experimental program for triple-Higgs searches at the LHC, with emphasis on CMS and ATLAS. I will discuss how the field has developed from a prospective idea into a concrete analysis effort, supported by two dedicated HHH workshops and a recent community white paper that helped consolidate the physics case, benchmark scenarios, and experimental priorities. I will then present the first experimental results, including the fully hadronic HHH→bbbbbb final state and complementary channels with photons, highlighting the main challenges: tiny signal yields, large QCD backgrounds, combinatorial ambiguities, and the need for robust heavy-flavour identification.
Finally, I will discuss how modern machine-learning tools are reshaping the reach of HH and HHH searches. Graph-based heavy-flavour tagging, jet-energy regression, boosted-object reconstruction, and improved Run 3 triggers are already strengthening the program. Looking ahead, I will introduce a high-performance jet-charge tagger based on charged-particle and secondary-vertex information, which can infer whether a heavy-flavour jet originates from a quark or an antiquark. This new handle can improve Higgs-candidate pairing, suppress combinatorial backgrounds, and enhance sensitivity in H→bb, H→cc, HH→bbbb, and ultimately HHH→bbbbbb searches.