Abstract
The spectrum of energy density fluctuations, baryon asymmetry, and coherent large-scale magnetic fields are the three observables that provide crucial information on physics at very high energies. Inflation can only provide a mechanism to explain the density perturbations, and the origin of primordial magnetic fields and baryon asymmetry require physics beyond the standard models of cosmology and particle physics. In this work, we show that the mechanism that leads to primordial helical fields also leads to baryogenesis at the beginning of the radiation-dominated epoch. The model we consider here consists of mass dimension 6 operators that include Riemann coupling between gravity and electromagnetic field without extending the Standard Model of particle physics. We explicitly show that the generation of primordial helical magnetic fields leads to baryogenesis. We further show that the model predicts the observed amount of baryon asymmetry of the Universe for a range of reheating temperatures consistent with the observations.
Highlights
Understanding the physical processes in the very early Universe is a crucial ingredient for deciphering the physics at energies that we cannot currently probe in terrestrial experiments
The origin of primordial magnetic fields and baryon asymmetry of the Universe are still unresolved issues and require physics beyond the standard models of cosmology and particle physics. This leads to the following questions: As the Universe cooled, from the early Universe to today, what were the processes responsible for generating baryon asymmetry and large-scale magnetic fields? Are these processes cosmological or particle physics or both? Since both require physics beyond the standard model, there is a tantalizing possibility that the same new physics can solve both
Our mechanism requires stretching of the primordial helical magnetic fields to superhorizon scales during inflation—the same mechanism that leads to primordial density perturbations
Summary
Understanding the physical processes in the very early Universe is a crucial ingredient for deciphering the physics at energies that we cannot currently probe in terrestrial experiments. Within the standard electrodynamics, inflation cannot provide a mechanism to generate large-scale B fields This is because in 4-dimensions electromagnetic field is conformally invariant. The origin of primordial magnetic fields and baryon asymmetry of the Universe are still unresolved issues and require physics beyond the standard models of cosmology and particle physics. This leads to the following questions: As the Universe cooled, from the early Universe to today, what were the processes responsible for generating baryon asymmetry and large-scale magnetic fields? The reduced Planck mass is denoted by MP 1⁄4 ð8πGÞ−1=2
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