A 95 GeV Higgs boson and spontaneous CP-violation at the finite temperature

TL;DR

This paper proposes a complex singlet scalar extension of the two-Higgs-doublet model to explain a 95 GeV Higgs boson signal, baryon asymmetry, and spontaneous CP-violation at finite temperature, consistent with experimental constraints.

Contribution

It introduces a model that simultaneously accounts for the 95 GeV Higgs signals, baryon asymmetry, and spontaneous CP-violation, linking collider anomalies with cosmological phenomena.

Findings

The model explains the 95 GeV diphoton and b-bbar excesses.

It achieves spontaneous CP-violation at finite temperature.

It satisfies collider and electric dipole moment constraints.

Abstract

The ATLAS and CMS collaborations reported a diphoton excess in the invariant mass distribution around the 95.4 GeV with a local significance of $3.1\sigma$. Moreover, there is another $2.3\sigma$ local excess in the $b\bar{b}$ final state at LEP in the same mass region. A plausible solution is that the Higgs sector is extended to include an additional Higgs boson with a mass of $95.4$ GeV. We study a complex singlet scalar extension of the two-Higgs-doublet model in which the 95.4 GeV Higgs is from the mixing of three CP-even Higgs fields. In addition, the extended Higgs potential can achieve spontaneous CP-violation at the finite temperature and restore CP symmetry at the present temperature of the Universe. We find that the model can simultaneously explain the baryon asymmetry of the Universe, the diphoton and $b\bar{b}$ excesses around the 95.4 GeV while satisfying various relevant constraints including the experiments of collider and electric dipole moment.