Big Bang nucleosynthesis and particle dark matter

Abstract

Following a recent suggestion of axion cooling of photons between the nucleosynthesis and recom-bination epochs in the Early Universe, we investigate a hybrid model with both axions and relic supersymmetric particles. In this model we demonstrate that the 7 Li abundance can be consistent with observations without destroying the important concordance of deuterium abundance. PACS numbers: 26.35.+c, 98.80.Cq, 98.80.Es, 98.80.Ft Introduction-Low-metallicity halo stars exhibit a plateau of 7 Li abundance, indicating the primordial origin of 7 Li [1]. However, the amount of 7 Li needed to be consistent with the cosmic microwave background observations [2] is significantly more than 7 Li observed in old halo stars [3]. (Even though 7 Li can be both produced and destroyed in stars, old halo dwarf stars are expected to have gone through little nuclear processing). Recent improvements in the observational and experimental data seem to make the discrepancy worse [4, 5]. One possible solution is to invoke either nuclear physics hitherto excluded from the Big-Bang Nucleosynthesis (BBN) [6, 7] or new physics such as variations of fundamental couplings [8, 9], and particles not included in the Standard Model [10-42]. Effects of massive neutral relic particles on BBN were extensively studied [10-28].

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

“…Assuming that observations will confirm a somewhat higher 6 Li abundance with respect to the computed CDM ( Lambda Cold Dark Matter ) model value, the only remaining possibilities to explain the discrepancy are very special astrophysical processes like stellar flare in-situ lithium production [41] . Other possibilities are unknown physical processes or new physics scenarios [42][43][44][45] .…”

Production and evolution of Li, Be, and B isotopes in the Galaxy

“…Mechanisms for Li destruction involving physics beyond the Standard model have been proposed in the literature (see Jedamzik & Pospelov 2009, and references therein). Astrophysical mechanisms, such as astration of high primordial Li by a pre-galactic Pop.…”

An extremely primitive star in the Galactic halo

“…The theoretical primordial Li abundance 1 is a factor of 2 to 3 larger than the value observed on the Spite plateau. A number of explanations of this discrepancy have been proposed, which range from stellar phenomena, such as atomic diffusion 21 , to new physics leading to a different big bang nucleosynthesis 22 .…”