High scale electroweak phase transition: baryogenesis & symmetry non-restoration

Abstract

We explore the possibility that the electroweak phase transition happens at a scale much higher than the electroweak scale today. In this context, high scale CP-violating sources for electroweak baryogenesis are not constrained by low-energy experiments. We propose a scenario of high-scale electroweak baryogenesis linked to flavour physics. This scenario allows for a period of enhanced Yukawa couplings during the evolution of the universe, which source time-dependent CP violation. The electroweak symmetry is never restored after the high-scale phase transition due to negative contributions to the Higgs thermal mass squared from a large number of additional electroweakscale neutral scalars coupling to the Higgs. As a result, the washout of the baryon asymmetry is avoided.

Coset cosmology

“…(11b), such that at finite temperature the h = f π minimum is favoured. This can in principle realise the idea of electro-weak baryogenesis above the weak scale [61][62][63] (see also [19]) without requiring a large number of fields.…”

“…If this happens at a temperature T 130 GeV electro-weak sphalerons remain frozen and the baryon asymmetry is not washed out. As argued in [61][62][63], the advantage of having electro-weak baryogenesis well above the weak scale is that the required CP violation is much less constrained than in the increasingly challenged models at the weak scale.…”

Discovery Goals and Opportunities: A Defense of BSM-Oriented Exploration over Signalism

“…Already, there are innumerable studies of BSM ideas for early universe cosmology and astrophysics that will be tested and excluded/confirmed, leading to a vastly deeper understanding of nature. These ideas of testing new physics [36] are wide-ranging, including probes of first-order phase transitions [24], tests of early universe equation of state [48,49,93], probes of axions physics [90], tests of and early kination phase in the early universe, and much more, all made possible by the discovery of gravity waves.…”

The serendipity of electroweak baryogenesis

“…This is illustrated on fig. 2 where the Yukawa coupling is shown as a function of φ for different choices of n. The choice of n is a parametrisation of the trajectory in the (Higgs, Flavon) field space during the phase transition, which can be determined through a dedicated analysis of tunneling in a 2-field space [5][6][7]. Typically, for a simple polynomial potential, the lighter the flavon, the larger n can be.…”

“…On the other hand, in most cases, Yukawa couplings are dynamical and it is natural to investigate about their cosmological evolution. In this article we report on recent work connecting flavour cosmology and baryogenesis [1][2][3][4][5][6][7].…”