Speaker
Description
Experimental evidence shows that the Universe is currently permeated by large-scale magnetic fields whose strength is expected to reach the nano-Gauss level. The origin of these magnetic fields remains a matter of active investigation.
Although no consensus has yet been reached on the exact paradigm that explains these observations, the literature has increasingly favored primordial magnetogenesis during inflation. This class of models generates magnetic fields by breaking the conformal invariance of the electromagnetic Lagrangian. Unlike astrophysical magnetogenesis, it naturally produces fields with coherence lengths of the order of a megaparsec, in agreement with observational evidence.
In this talk, we show that magnetogenesis can be supported by an inflationary scenario involving a stealth scalar field, i.e., a field with a vanishing stress-energy tensor. Remarkably, we find that the introduction of the stealth field provides a natural explanation for the non-conformal power-law coupling that has been widely studied in the literature. We support our analysis with numerical results based on the gradient expansion formalism, which also accounts for charged-particle production through the Schwinger mechanism in the presence of strong electric fields.