The X^- Solution to the ^6Li and ^7Li Big Bang Nucleosynthesis Problems

Abstract

The ${}^6$Li abundance observed in metal poor halo stars appears to exhibit a plateau as a function of metallicity similar to that for ${}^7$Li, suggesting a big bang origin. However, the inferred primordial abundance of ${}^6$Li is $\sim$1000 times larger than that predicted by standard big bang nucleosynthesis for the baryon-to-photon ratio inferred from the WMAP data. Also, the inferred ${}^7$Li primordial abundance is 3 times smaller than the big bang prediction. We here describe in detail a possible simultaneous solution to both the problems of underproduction of ${}^6$Li and overproduction of ${}^7$Li in big bang nucleosynthesis. This solution involves a hypothetical massive, negatively-charged leptonic particle that would bind to the light nuclei produced in big bang nucleosynthesis, but would decay long before it could be detected. We consider only the $X$-nuclear reactions and assume that the effect of decay products is negligible, as would be the case if lifetime were large or the mass difference between the charged particle and its daughter were small. An interesting feature of this paradigm is that, because the particle remains bound to the existing nuclei after the cessation of the usual big bang nuclear reactions, a second longer epoch of nucleosynthesis can occur among $X$-nuclei. We confirm that reactions in which the hypothetical particle is transferred can occur that greatly enhance the production of ${}^6$Li while depleting ${}^7$Li. We also identify a new reaction that destroys large amounts of ${}^7$Be, and hence reduces the ultimate ${}^7$Li abundance. Thus, big-bang nucleosynthesis in the presence of these hypothetical particles, together with or without an event of stellar processing, can simultaneously solve the two Li abundance problems.

18 pages, 7 figures, minor changes and references added, ApJ accepted

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Cited by in corpus (27)

• The Primordial Lithium Problem
• Big Bang Nucleosynthesis as a Probe of New Physics
• Production and evolution of Li, Be and B isotopes in the Galaxy
• Frontiers in Nuclear Astrophysics
• Heavy Hadrons in Nuclear Matter
• Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios
• Cosmic Rays from Dark Matter Annihilation and Big-Bang Nucleosynthesis
• Resonant Destruction as a Possible Solution to the Cosmological Lithium Problem
• High-energy break-up of 6Li as a tool to study the Big-Bang nucleosynthesis reaction 2H(alpha,gamma)6Li
• New Nuclear Physics for Big Bang Nucleosynthesis
• Higher D or Li: Probes of Physics beyond the Standard Model
• Effect of Long-lived Strongly Interacting Relic Particles on Big Bang Nucleosynthesis
• Revised Big Bang Nucleosynthesis with long-lived negatively charged massive particles: updated recombination rates, primordial 9Be nucleosynthesis, and impact of new 6Li limits
• New Constraints on Radiative Decay of Long-Lived Particles in Big Bang Nucleosynthesis with New ${}^4$He Photodisintegration Data
• Cosmological solutions to the Lithium problem: Big-bang nucleosynthesis with photon cooling, $X$-particle decay and a primordial magnetic field
• New results on catalyzed BBN with a long-lived negatively-charged massive particle
• Stau relic density at the Big-Bang nucleosynthesis era consistent with the abundance of the light element nuclei in the coannihilation scenario
• Destruction of 7Be in big bang nucleosynthesis via long-lived sub-strongly interacting massive particles as a solution to the Li problem
• Review on Effects of Long-lived Negatively Charged Massive Particles on Big Bang Nucleosynthesis
• Solution to Big-Bang Nucleosynthesis in Hybrid Axion Dark Matter Model
• Non-detection of ${}^6$Li in Spite plateau stars with ESPRESSO
• Recent results in nuclear astrophysics
• 7Be charge exchange between 7Be3+ ion and exotic long-lived negatively charged massive particle in big bang nucleosynthesis
• An Enhanced Cosmological Li6 Abundance as a Potential Signature of Residual Dark Matter Annihilations
• Study of the ${}^7$Be($d$,${}^3$He)${}^6$Li* reaction at 5 MeV/u
• Primordial Nucleosynthesis
• Big Bang Nucleosynthesis with long-lived strongly interacting relic particles