Overview on low mass scalars at $e^+e^-$ facilities -- theory

TL;DR

This paper reviews theoretical scenarios involving low-mass scalar particles that could be explored at future electron-positron colliders, emphasizing models with scalars below 125 GeV and recent developments in the field.

Contribution

It provides an updated overview of low-mass scalar models and signatures, highlighting new theoretical proposals since previous literature.

Findings

Multiple new physics scenarios remain compatible with current constraints.

Future $e^+e^-$ colliders could probe these low-mass scalar models effectively.

Recent theoretical developments expand the potential signatures to be investigated.

Abstract

I give a short summary of scenarios with new physics scalars that could be investigated at future $e^+e^-$ colliders. I concentrate on cases where at least one of the additional scalar has a mass below 125 GeV, and discuss models where this could be realized. In general, there are quite a few additional new physics scenarios and signatures that are still allowed by current constraints and should be investigated in more detail at future $e^+e^-$ machines. Most of the material presented here has already been discussed in arXiv:2307.15962, and I therefore try to focus on novel developments since then.