Federico Urban: Three-magnetic fields

 I will discuss a qualitatively new possibility for the generation of
cosmic magnetic fields in the context of inflation.  The mechanism rests
on the dynamics of three-forms as inflating fields, whose uniquely
gauge-invariant coupling to light gives rise to new solutions in the
equations of motion for the latter, which in turn allow for exponential
amplification of the photon's vacuum fluctuations.  We will dwell into
some details (backreactions, spectrum) as well as present latest
developments and potential issues.