ATLAS searches for additional scalars and exotic Higgs boson decays with the LHC Run 2 dataset

TL;DR

This paper reviews ATLAS's extensive searches for additional scalar particles and exotic Higgs decays using the LHC Run 2 data, highlighting new results, constraints on models, and innovative techniques.

Contribution

It provides a comprehensive summary of new and extended searches for exotic Higgs phenomena with improved limits and novel experimental methods.

Findings

No statistically significant excesses observed.

Stronger exclusion limits on extended Higgs models.

Identification of new search channels for future exploration.

Abstract

This report reviews the published results of searches for possible additional scalar particles and exotic decays of the Higgs boson performed by the ATLAS Collaboration using up to 140 fb$^{-1}$ of 13 TeV proton-proton collision data collected during Run 2 of the Large Hadron Collider. Key results are examined, and observed excesses, while never statistically compelling, are noted. Constraints are placed on parameters of several models which extend the Standard Model, for example by adding one or more singlet or doublet fields, or offering exotic Higgs boson decay channels. Summaries of new searches as well as extensions of previous searches are discussed. These new results have a wider reach or attain stronger exclusion limits. New experimental techniques that were developed for these searches are highlighted. Search channels which have not yet been examined are also listed, as these provide insight into possible future areas of exploration.