Abstract
We revisited the scenario of electroweak baryogenesis in the presence of large Yukawa couplings, in which it was found previously that a strongly first order electroweak phase transition can occur with the Higgs mass at its observed value of 125 GeV. Given the sensitivity of the running of the Higgs quartic coupling on the Yukawa coupling constants, we find that the addition of order one Yukawa couplings beyond the top quark drastically lowers the scale at which the Higgs potential becomes unstable. Specifically, even with only one additional order one Yukawa coupling, the scalar potential becomes unstable already at the TeV scale, assuming the Standard Model values for the Higgs sector parameters at the electroweak scale. Furthermore, by assuming the Standard Model values for the Higgs sector parameters at the TeV scale, the quartic coupling constant is driven to be larger than its Standard Model value at the electroweak scale. This in turn predicts a much lighter Higgs mass than the measured value of 125 GeV. In this scenario, the strength of the electroweak phase transition is also significantly weakened.
Highlights
The origin of the observed cosmological matter-antimatter asymmetry of the Universe remains an outstanding question in both particle physics and cosmology
In electroweak baryogenesis (EWBG), the out-ofequilibrium condition is achieved if the electroweak phase transition (EWPT) is strongly first order
There are three effects of the large Yukawa couplings during the electroweak phase transition: (i) In the T 1⁄4 0 one-loop corrections, the large Yukawa couplings result in the lowering of the scalar potential in the region of 0 < hφi < v weakening the phase transition; (ii) the finite temperature one-loop correction from the fermions adds to the potential and strengthens the phase transition; (iii) the large Yukawa coupling present in the Higgs daisy correction strengthens the phase transition
Summary
The origin of the observed cosmological matter-antimatter asymmetry of the Universe remains an outstanding question in both particle physics and cosmology. This allows for a first-order phase transition and EWBG This scenario does not suffer from the problems to be discussed here, because the heavy quarks only couple to the second Higgs doublet and do not impact substantially the renormalization group equations (RGEs) of the standard model Higgs parameters. If the value of the quartic coupling in the UV is kept at the standard model value, the renormalization group corrections driven by large Yukawa couplings lead to a quartic coupling value that is larger than the standard model value at the weak scale This results in a light Higgs mass that is in conflict with observation.
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