ATLAS DBL sub-group: AZH prospects from a theoretical perspective

Wednesday 15 Nov 2023, 15:00 → 17:00 Europe/Zurich

1/1-025 (CERN)

15:00 → 15:30 AZH smoking gun paper

In this talk we investigate the capability of the new ATLAS searches for $A \to ZH$ decays in $ell^+ \ell^- t \bar t$ and $\nu \nu b \bar b$ final states to probe the electroweak phase transition in the early Universe. In the framework of the Two Higgs Doublet Model (2HDM), we investigate the impact of the new searches on the 2HDM parameter space, paying special attention to parameter space regions that predict a strong first order electroweak phase transition. We discuss the complementarity with other LHC searches, and we analyze the interplay of collider searches and space based gravitational wave experiments. We furthermore show that the $3\sigma$ excess observed at $m_A = 650$~GeV and $m_H = 450$~GeV can be described in the 2HDM, where the preferred parameter space falls within the region suitable for a realization of a strong first-order phase transition. The GW signal produced during the transition in the early universe might be in reach of LISA. Finally, we

Speaker: Kateryna Radchenko Serdula (DESY)

Smoking_gun_Radchenko.pdf