Effective 2HDM Yukawa Interactions and a Strong First-Order Electroweak Phase Transition

TL;DR

This paper explores how modifications in top-Higgs interactions within the 2HDM can support a strong first-order electroweak phase transition, consistent with current data, and discusses implications for future LHC searches.

Contribution

It demonstrates the compatibility of 2HDM modifications with current Higgs data and highlights the potential of existing LHC searches to discover new physics related to electroweak phase transition.

Findings

Modifications in top-Higgs interactions can enable a strong first-order electroweak phase transition.

Current Higgs data do not exclude these modifications.

LHC searches in $t\bar t$ and four top final states are promising for discovering 2HDM-like signals.

Abstract

The top quark as the heaviest particle in the Standard Model (SM) defines an important mass scale for Higgs physics and the electroweak scale itself. It is therefore a well-motivated degree of freedom which could reveal the presence of new interactions beyond the SM. Correlating modifications of the top-Higgs interactions in the 2-Higgs-Doublet Model (2HDM), we analyse effective field theory deformations of these interactions from the point of view of a strong first-order electroweak phase transition (SFOEWPT). We show that such modifications are compatible with current Higgs data and that an SFOEWPT can be tantamount to a current overestimate of exotic Higgs searches' sensitivity at the LHC in $t\bar t$ and four top quark final states. We argue that these searches remain robust from the point of accidental signal-background interference so that the current experimental strategy might well lead to 2HDM-like discoveries in the near future.