Did Something Decay, Evaporate, or Annihilate during Big Bang Nucleosynthesis?
Abstract
Results of a detailed examination of the cascade nucleosynthesis resulting from the putative hadronic decay, evaporation, or annihilation of a primordial relic during the Big Bang nucleosynthesis (BBN) era are presented. It is found that injection of energetic nucleons around cosmic time 1000 sec may lead to an observationally favored reduction of the primordial Li7/H yield by a factor 2 - 3. Moreover, such sources also generically predict the production of the Li6 isotope with magnitude close to the as yet unexplained high Li6 abundances in low-metallicity stars. The simplest of these models operate at fractional contribution to the baryon density Omega_b h^2> 0.025, slightly larger than that inferred from standard BBN. Though further theoretical and experimental study is required, such sources, as for example a light several GeV neutralino dark matter particle, or an unstable gravitino in the TeV range of abundance Omega h^2\sim 5\times 10^{-4} show promise to explain both the Li6 and Li7 abundances in low metallicity stars.Keywords
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