http://arxiv.org/abs/1704.06897
Like Scalar Galileons, Einstein-Hilbert action and the Lovelock extensions contain higher order derivatives in action, however their equations of motion are second order. We are lead to ask: Can there exist a corresponding action for spin-1 or electromagnetic fields? By demanding three conditions – theory be described by vector potential $A^\mu$ and its derivatives, Gauge invariance be satisfied, and equations of motion be linear in second derivatives of vector potential – we construct a higher derivative electromagnetic action which does not have ghosts and preserve gauge invariance. We show that the action breaks conformal invariance explicitly and leads to generation of magnetic field during inflation. One unique feature of our model is that appreciable magnetic fields are generated at small wavelengths while tiny magnetic fields at large wavelengths that are consistent with current observations.
D. Nandi and S. Shankaranarayanan
Tue, 25 Apr 17
11/59
Comments: 10 pages, 0 figure