Pheno2019 - ATLAS Searches for VH/HH Resonances

This week I attended the Pheno conference in Pittsburgh, PA. This conference is one primarily oriented for theorists to come together and discuss various ideas in particle phenomenology, theory, as well as contributions from astrophysics and cosmology. Each morning started with plenary sessions, covering interesting subjects, then in the afternoon they broke up into many different parallel sessions, where primarily students and postdocs got to show a lot of work.

My talk was from the experimental side, where I covered ATLAS searches for VH/HH resonances. Since the Higgs field is responsible for mass, the quanta of it, the Higgs boson, interacts all massive particles. In the search for new particles (which are observed as resonances) beyond the Standard Model (BSM), this feature of the Higgs boson makes it an interesting tool.

In this talk, I summarize ongoing searches for new particles that may decay to either two Higgs bosons (HH) or a Higgs boson and a either a W or Z boson, generically called vector bosons (VH). There are 2 major VH searches presented, one where the vector boson decays to leptons (like electrons), and one where the vector boson decays into a pair of quarks. I present these searches, and the combined exclusion limits for the two, where we’ve ruled out resonances below about 3 TeV for a model known as Heavy Vector Triplets (HVT). The HVT model is a BSM model that extends the SM by adding heavier versions of the W and Z bosons which are spin-1 particles.

For di-Higgs searches, I present the three predominant channels, bbbb, bbtt, and 𝛾𝛾bb (which I directly work on), as well as the newly published combination of the two from last fall. From those searches, limits are set on the Two-Higgs Doublet Model, which extends the SM by adding a heavier Higgs, 2 charged Higgs, and a pseudoscalar. The particle that we set limits on are the heavier Higgs, excluding between 260-462 GeV for this spin-0 particle. Additionally, we look at the Randall-Sundrum model, a warped extra dimensions model that addresses the hierarchy problem, introducing a spin-2 Kaluza-Klein graviton, which we set limits on.

The full slide deck can be found here.

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