Abstract
In this paper, we study the simultaneous evolution of baryon asymmetry and hypermagnetic field amplitude assuming an early matter domination. We contrast our results to the conventional case where radiation domination during early universe is assumed. We show that the baryon asymmetry and the hypermagntic field amplitude can change by orders of magnitude if we assume a non-standard history of cosmology. That is because the Hubble rate determines which processes are efficient. We find that a change in Hubble rate can have a significant impact on when the weak sphalerons become active. As a result of a change in the evolution of baryonic asymmetry, alters the evolution of hypermagnetic field amplitude. It is known that if the hypermagnetic field amplitude is large enough, it can save the baryon asymmetry from diminishing. We show that whether a small seed of hypermagnetic field amplitude can be amplified to a large enough value will strongly depend on the history of cosmology.
Highlights
According to our knowledge of the big bang nucleosynthesis (BBN) [1] and the cosmic microwave background (CMB) [2], we expect the universe to be in the stage of radiation domination (RD) around the temperature of (10 MeV-eV)
We show that the baryon asymmetry and the hypermagntic field amplitude can change by orders of magnitude if we assume a nonstandard history of cosmology
Since EMD arise naturally in many beyond the SM solutions, we merely focus on how the evolution of baryon asymmetry and hypermagnetic field amplitude will change in the era of early matter domination
Summary
According to our knowledge of the big bang nucleosynthesis (BBN) [1] and the cosmic microwave background (CMB) [2], we expect the universe to be in the stage of radiation domination (RD) around the temperature of (10 MeV-eV). That will give sphalerons less time to eat up the asymmetry Notice that in this case, the matter domination should not be too long such that the electron Yukawa enters equilibrium after. We will consider the effect of the hypermagnetic field on the evolution of baryon asymmetry in the cases of both standard cosmology and a universe with an EMD. Since EMD arise naturally in many beyond the SM solutions, we merely focus on how the evolution of baryon asymmetry and hypermagnetic field amplitude will change in the era of early matter domination.
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