On Extra Top Yukawa Couplings of a Second Higgs Doublet

Abstract

A very likely New Physics in plain sight, but that the community does not see, is a second Higgs doublet that has a second set of Yukawa couplings. The extra tt and tc couplings can each drive baryogenesis, with O(1) Higgs quartic couplings providing a first order electroweak phase transition. A natural cancellation mechanism can tame electron EDM, if extra ee, tt couplings “know” the known fermion mass and mixing hierarchies. Colliding c with g produces tH/A, bH+ via extra tc coupling, and together with extra tt coupling give ttc(bar), ttt(bar), and btb(bar) signatures at the LHC. Extra tu coupling can also be probed, but more definitive would be the B to μν and τν decay rate ratio. Myriad extra Yukawa couplings can make an impact on flavor physics and CP violation, including on muon g-2. The opening to the prelude of a new physics Higgs and flavor era may unfold before us.