Abstract
It has been considered that baryogenesis models without a generation of $B$-$L$ asymmetry such as the GUT baryogenesis do not work since the asymmetry is washed out by the electroweak sphalerons. Here, we point out that helical hypermagnetic fields can be generated through the chiral magnetic effect with a chiral asymmetry generated in such baryogenesis models. The helical hypermagnetic fields then produce baryon asymmetry mainly at the electroweak symmetry breaking, which remains until today. Therefore, the baryogenesis models without $B$-$L$ asymmetry can still be the origin of the present baryon asymmetry. In particular, if it can produce chiral asymmetry mainly carried by right-handed electrons of order of $10^{-3}$ in terms of the chemical potential to temperature ratio, the resultant present-day baryon asymmetry can be consistent with our Universe, although simple realizations of the GUT baryogenesis are hard to satisfy the condition. We also argue the way to overcome the difficulty in the GUT baryogenesis. The intergalactic magnetic fields with $B_0\sim 10^{-16 \sim 17}$ G and $\lambda_0 \sim 10^{-2\sim3}$ pc are the smoking gun of the baryogenesis scenario as discussed before.
Highlights
Baryon asymmetry of the Universe (BAU) is a longstanding problem in particle physics and cosmology
We can imagine the following scenario: (i) the grand unified theories (GUTs) baryogenesis first generates the B þ L and chiral asymmetry, (ii) maximally helical hyperMFs are generated from the chiral asymmetry while B þ L asymmetry is eventually damped, and (iii) the hyperMFsproduce baryon asymmetry, especially at the EW symmetry breaking, which lasts against the EW sphalerons
We discussed the possibility for baryogenesis models without B − L generation such as GUT baryogenesis to be indirectly responsible for the present BAU
Summary
Baryon asymmetry of the Universe (BAU) is a longstanding problem in particle physics and cosmology. Such primordial helical hyperMFs can have a strong impact on cosmology [7] They can be the seed for the galaxy and galaxy-cluster MFs and remain until today as the intergalactic MFs. the baryon asymmetry is (re)generated through the Standard Model (SM) chiral anomaly [8,9], which is not completely washed out by the EW sphalerons [9,10]. We can imagine the following scenario: (i) the GUT baryogenesis first generates the B þ L and chiral asymmetry, (ii) maximally helical hyperMFs are generated from the chiral asymmetry while B þ L asymmetry is eventually damped, and (iii) the hyperMFs (re)produce baryon asymmetry, especially at the EW symmetry breaking, which lasts against the EW sphalerons.
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