Inflationary magnetogenesis with helical coupling

We describe a simple scenario of inflationary magnetogenesis based on a helical coupling to electromagnetism. It allows to generate helical magnetic fields of strength of order up to $10^{- 7}\,\text{G}$, when extrapolated to the current epoch, in a narrow spectral band centered at any physical wavenumber by adjusting the model parameters. Additional constraints on magnetic fields arise from the considerations of baryogenesis and, possibly, from the Schwinger effect of creation of charged particle-antiparticle pairs.
Comment: 5 pages, 1 figure. This work is based on the results presented at the XI Bolyai-Gauss-Lobachevskii (BGL-2019) Conference: Non-Euclidean, Noncommutative Geometry and Quantum Physics, Kiev, May 19-24. Compared to arXiv:1902.05894, a smooth analytic interpolating coupling function is used with an exact solution