Seminarium "Teoria cząstek elementarnych i kosmologia"

Consider the possibility that there were strong electric (and magnetic) fields in the very early universe. How does the pair creation of charged particles out of vacuum (Schwinger effect) behave in a de Sitter (dS) spacetime? Can it shut off or enhance the production of electric fields? Formal exact calculations of the induced current show interesting peculiarities. For instance, one finds negative values of the conductivity for light charge carriers and weak fields — even in the limit of vanishing electric field — which could trigger an spontaneous electrification of dS. Furthermore, for heavy charge carriers one does not recover the exponential suppression of the current, expected from gravitational pair creation. What is the meaning of that? Is there anything wrong with the regularisation of the formal calculation? Perhaps we are simply misunderstanding the results? In this talk, I will clarify the above mentioned behaviors — some are related to the birefringence of the QED vacuum and some are spurious — and I will discuss the possible impacts in inflationary magnetogenesis.