Singlet scalar and 2HDM extensions of the Standard Model: CP-violation and constraints from $(g-2)_\mu$ and $e$EDM

TL;DR

This paper investigates scalar extensions of the Standard Model, focusing on their effects on muon g-2 and electron EDM, and finds that CP-violation constraints eliminate viable parameter space.

Contribution

It provides a comprehensive analysis of CP-violating scalar models' compatibility with muon g-2 and electron EDM experimental bounds.

Findings

CP-violation negates viable parameter space for explaining muon g-2 discrepancy.

Light scalars are generally required to account for muon g-2 in CP-conserving models.

Current constraints exclude parameter regions where both muon g-2 and electron EDM are satisfied.

Abstract

We study popular scalar extensions of the Standard Model, namely the singlet extension, the 2-Higgs doublet model (2HDM) and its extension by a singlet scalar. We focus on the contributions of the added scalars to the anomalous magnetic moment of the muon, $(g-2)_\mu$ in the presence of CP-violation, and the electric dipole moment of the electron ($e$EDM) in these models. In the absence of CP-violation, CP-even and CP-odd scalars contribute with an opposite sign to the anomalous magnetic moment of the muon and as a result these models generally require very light scalars to explain the observed discrepancy in $(g-2)_\mu$. We study the effect of CP-violation on the anomalous magnetic moment of the muon and its compatibility with the $e$EDM constraints. We show that given the current status of the global set of constraints applied on all values of $\cot\beta$, in the CP-violating scalar extensions, there exist no viable parameter space in agreement with both $a_\mu$ and $e$EDM bounds.