Progress on cosmological magnetic fields

A variety of observations impose upper limits at the nano Gauss level on magnetic fields that are coherent inter-galactic scales while blazar indicate a lower bound $\sim 10^{-16}$ Gauss. Such can play an important astrophysical role, for example cosmic recombination and during structure formation, also provide crucial information particle physics in early universe. Magnetic with significant energy density could have been produced electroweak phase transition. The evolution survival sub-horizon universe, however, depends helicity which is related to violation symmetries fundamental interactions. generation requires new CP violating interactions be tested by accelerator experiments via decay channels Higgs particle.