Electroweak Baryogenesis with Anomalous Higgs Couplings

TL;DR

This paper explores how anomalous Higgs couplings within an effective field theory can enable electroweak baryogenesis by inducing a strongly first-order phase transition and generating the observed matter-antimatter asymmetry.

Contribution

It demonstrates that Higgs cubic and CP-violating Higgs-top couplings can drive baryogenesis within a non-linear electroweak framework, consistent with current experimental constraints.

Findings

A range of anomalous couplings allows successful baryogenesis.

The phase transition is strongly first-order with non-zero Higgs VEV in both phases.

Predictions can be tested with current and future LHC data.

Abstract

We investigate feasibility of efficient baryogenesis at the electroweak scale within the effective field theory framework based on a non-linear realisation of the electroweak gauge symmetry. In this framework the LHC Higgs boson is described by a singlet scalar field, which, therefore, admits new interactions. Assuming that Higgs couplings with the eletroweak gauge bosons are as in the Standard Model, we demonstrate that the Higgs cubic coupling and the CP-violating Higgs-top quark anomalous couplings alone may drive the a strongly first-order phase transition. The distinguished feature of this transition is that the anomalous Higgs vacuum expectation value is generally non-zero in both phases. We identify a range of anomalous couplings, consistent with current experimental data, where sphaleron rates are sufficiently fast in the 'symmetric' phase and are suppressed in the 'broken' phase and demonstrate that the desired baryon asymmetry can indeed be generated in this framework. This range of the Higgs anomalous couplings can be further constrained from the LHC Run 2 data and be probed at high luminosity LHC and beyond.