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

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 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.