Big Bang nucleosynthesis in a weakly non-ideal plasma
  We propose a correction of the standard Big Bang nucleosynthesis (BBN)
scenario to resolve the primordial lithium problem by considering a possibility
that the primordial plasma can deviate from the ideal state. In the standard
BBN, the primordial plasma is assumed to be ideal, with particles and photons
satisfying the Maxwell-Boltzmann and Planck distribution, respectively. We
suggest that this assumption of the primordial plasma being ideal might
oversimplify the early Universe and cause the lithium problem. We find that
deviation of photon distribution from the Planck distribution, which is
parameterised with the help of Tsallis statistics, can resolve the primordial
lithium problem when the particle distributions of the primordial plasma still
follow the MaxwellBoltzmann distribution. We discuss how the primordial plasma
can be weakly non-ideal in this specific fashion and its effects on the cosmic
evolution.
