EFFECTS OF MAGNETIC-FIELDS ON PRIMORDIAL NUCLEOSYNTHESIS

We discuss here several effects of strong magnetic fields on the synth esis of light elements during the big-bang. They include: changes in t he reaction rates, variation in the expansion rate of the Universe, pa rticle masses shift and the modification of the thermodynamical proper ties of the QED plasma. Including these effects in the standard nucleo synthesis code we are able to discriminate their relative importance. Comparing our results with the observation we find that the allowed in tensity of inhomogeneous fields at the end of the nucleosynthesis is 3 x10(10) Gauss.