Primordial magnetic fields and dynamos from parity violated torsion

Abstract

It is well known that torsion induced magnetic fields may seed galactic dynamos, but the price one pays for that is the conformal and gauge invariance breaks and a tiny photon mass. More recently I have shown [L.C. Garcia de Andrade, Phys. Lett. B 468 (2011) 28] that magnetic fields decay in a gauge invariant non-minimal coupling theory of torsion is slow down, which would allow for dynamo action to take place. In this Letter, by adding a parity violation term of the type Rμνρσϵμνρσ to the non-coupling term, a magnetic dynamo equation is obtained. From dynamo equation it is shown that torsion terms only appear in the dynamo equation when diffusion in the cosmic plasma is present. Torsion breaks the homogeneity of the magnetic field in the universe. Since Zeldovich anti-dynamo theorem assumes that the spacetime should be totally flat, torsion is responsible for violation of anti-dynamo theorem in 2D spatial dimensions. Contrary to previous results torsion induced primordial magnetic fields cannot seed galactic dynamos since from torsion and diffusion coefficient the decaying time of the magnetic field is 106yrs, which is much shorter than the galaxy age.