Relativistic Electron Scattering and Big Bang Nucleosynthesis

Big bang nucleosynthesis (BBN) is a valuable tool to constrain the physics of the early universe. An assumption for calculating abundances of nuclei due to BBN is that they obey Maxwell-Boltzmann(MB) statistics. This assumption is shown to be questionable and the modification to it is found. Firstly, we recognize that the nuclear distributions should be influenced by their surrounding particles. A nucleus interacts with e+ - e- lot more than other particles. e+ - e- are relativistic during BBN and hence obey modified Maxwell-Juttner(mMJ) distribution. Given these we build a Langevin model for Brownian motion of a heavy particle(nuclei) in a bath of light particles(e+ - e-). By imposing equipartition of energy we obtain a modified distribution for nuclei, altered only by a factor in temperature than MB distribution. Monte-Carlo simulations were built to simulate the thermalization process and the distribution obtained for nuclei corroborated Langevin model solution. When employed for BBN calculations, this distribution alters the light-element abundances, and worsens the discrepancies between BBN and observed primordial light-element abundances possibly suggesting the need for new physics.