Baryogenesis in $SU(2)_{L}$ multiplet models

TL;DR

This paper explores how extensions of the Standard Model with new $SU(2)_L$ multiplet fields can generate the observed baryon asymmetry through sphalerogenesis, with testable predictions for future experiments.

Contribution

It demonstrates that $SU(2)_L$ multiplet models with CP-violating interactions can successfully produce the baryon asymmetry and are consistent with current experimental bounds.

Findings

Fermionic quintuplets and septuplets with TeV-scale masses can explain BAU.

The models predict observable signals in electron EDM measurements and collider searches.

Parameter regions are compatible with current bounds and accessible to future experiments.

Abstract

We investigate baryogenesis in Standard Model (SM) extensions with new $SU(2)_L$ multiplet fields. We focus on sphalerogenesis, in which the baryon asymmetry of the Universe (BAU) is generated through the gradual decoupling of CP-violating electroweak (EW) sphaleron-like processes. We show that the observed BAU can be reproduced when the new fields possess CP-violating Yukawa interactions, which leave a CP-violating dimension-six operator involving the $SU(2)_L$ gauge fields at low energies. As representative examples, we study models with fermionic $SU(2)_L$ quintuplets and septuplets, and find that these field masses should be $\mathcal{O}(1)\,\mathrm{TeV}$ to explain the BAU. We also show that viable parameter regions for the BAU are consistent with current bounds on the electron electric dipole moment and thoroughly probed by future measurements such as ACME III and by mono-lepton searches at the HL-LHC. Our results provide a concrete and phenomenologically testable ultraviolet completion of sphalerogenesis.