Neutron injection during primordial nucleosynthesis alleviates the   primordial 7Li problem
  We present a parametrized study of the effects of free thermal neutron injection on primordial nucleosynthesis, where both the rate and the time scale of injection are varied. This generic approach is found to yield a successful solution for reducing the 7Li abundance without causing significant problems to other elemental abundances. Our analysis demonstrates that hadronic injection, possibly due to decays or annihilations of dark matter particles with a mass of about 1 to 30 GeV, provides a possible solution to an outstanding problem in the standard Big Bang model. 
Daniel Albornoz Vasquez, Alexander Belikov, Alain Coc, Joseph Silk and   Elisabeth Vangioni
astro-ph.CO nucl-th