Cross-correlations between scalar perturbations and magnetic fields in bouncing universes

Understand

Bouncing scenarios offer an alternative to the inflationary paradigm for the generation of perturbations in the early universe.

• Recently, there has been a surge in interest in examining the issue of primordial magnetogenesis in the context of bouncing universes.
• As in the case of inflation, the conformal invariance of the electromagnetic action needs to be broken in bouncing scenarios in order to generate primordial magnetic fields which correspond to observed strengths today.
• The non-minimal coupling, which typically depends on a scalar field that possibly drives the homogeneous background, leads to a cross-correlation at the level of the three-point function between the perturbation in the scalar field and the magnetic fields.