Abstract

The simplest gauge invariant models of inflationary magnetogenesis are known to suffer from the problems of either large back reaction or strong coupling, which make it difficult to self-consistently achieve cosmic magnetic fields from inflation with a field strength larger than \$10^-32\$ Gauss today on the \$\Mpc\$ scale. Such a strength is insufficient to act as seeds for the galactic dynamo effect, which requires a magnetic field larger than \$10^-20\$ Gauss. In this paper we propose a new simple model, which avoids both the strong coupling and the back reaction problems, and can lead to cosmic magnetic fields from inflation as large as about \$10^-16\$ Gauss today on the \$\Mpc\$ scale, thus improving the previous result by 16 orders of magnitude. In the scenario presented here, the coupling function which breaks the conformal invariance of electromagnetism is non-monotonic with sharp features avoiding previous back reaction and strong coupling constraints.

Links and resources

Tags