The Diphoton Excess Inspired Electroweak Baryogenesis

TL;DR

This paper proposes a model where a 750 GeV diphoton resonance, interpreted as a pseudo-scalar singlet, can trigger a strong first-order electroweak phase transition and generate the universe's baryon asymmetry through electroweak baryogenesis.

Contribution

It introduces a new scalar singlet model explaining the diphoton excess and its role in electroweak baryogenesis, connecting collider signals with cosmological baryon asymmetry.

Findings

The scalar singlet can produce the diphoton excess via gluon fusion.

The model allows for a strongly first-order electroweak phase transition.

CP violation in scalar quark interactions can generate sufficient baryon asymmetry.

Abstract

A resonance in the diphoton channel with invariant mass $m_{\gamma \gamma} = 750$ GeV was claimed by the ATLAS and CMS collaborations at the run-2 LHC with $\sqrt{s}=13$ TeV. In this paper, we explain this diphoton excess as a pseudo-scalar singlet, which is produced at the LHC through gluon fusion with exotic scalar quarks running in the loop. We point out the scalar singlet might trigger a two-step electroweak phase transition, which can be strongly first oder. By assuming there are CP violations associated with interactions of the scalar quarks, the model is found to be able to generate adequate baryon asymmetry of the Universe through the electroweak baryogenesis mechanism. Constraints on the model are studied.