Electroweak Baryogenesis and Higgs Signatures

TL;DR

This paper investigates how modifications in Higgs boson properties linked to a strong electroweak phase transition could enable electroweak baryogenesis, and discusses implications for Higgs signatures at the LHC and the MSSM.

Contribution

It introduces a simplified model connecting Higgs properties, scalar fields, and electroweak baryogenesis, highlighting observable effects at the LHC and constraints on the MSSM.

Findings

Strong electroweak phase transition correlates with observable Higgs property modifications.

Higgs couplings to gluons and photons can be significantly altered in baryogenesis-favorable scenarios.

Discovery of SM-like Higgs couplings could exclude electroweak baryogenesis in the MSSM.

Abstract

We explore the connection between the strength of the electroweak phase transition and the properties of the Higgs boson. Our interest is in regions of parameter space that can realize electroweak baryogenesis. We do so in a simplified framework in which a single Higgs field couples to new scalar fields charged under SU(3)_c by way of the Higgs portal. Such new scalars can make the electroweak phase transition more strongly first-order, while contributing to the effective Higgs boson couplings to gluons and photons through loop effects. For Higgs boson masses in the range 115 GeV < m_h < 130 GeV, whenever the phase transition becomes strong enough for successful electroweak baryogenesis, we find that Higgs boson properties are modified by an amount observable by the LHC. We also discuss the baryogenesis window of the minimal supersymmetric standard model (MSSM), which appears to be under tension. Furthermore, we argue that the discovery of a Higgs boson with standard model-like couplings to gluons and photons will rule out electroweak baryogenesis in the MSSM.