Revised Big Bang Nucleosynthesis with Longlived, Negatively Charged Massive Particles: Updated Recombination Rates, Primordial ^{9}Be Nucleosynthesis, and Impact of New ^{6}Li Limits
Abstract
We extensively reanalyze the effects of a longlived, negatively charged massive particle, X ^{}, on big bang nucleosynthesis (BBN). The BBN model with an X ^{} particle was originally motivated by the discrepancy between the ^{6, 7}Li abundances predicted in the standard BBN model and those inferred from observations of metalpoor stars. In this model, ^{7}Be is destroyed via the recombination with an X ^{} particle followed by radiative proton capture. We calculate precise rates for the radiative recombinations of ^{7}Be, ^{7}Li, ^{9}Be, and ^{4}He with X ^{}. In nonresonant rates, we take into account respective partial waves of scattering states and respective bound states. The finite sizes of nuclear charge distributions cause deviations in wave functions from those of pointcharge nuclei. For a heavy X ^{} mass, m_{X} >~ 100 GeV, the dwave → 2P transition is most important for ^{7}Li and ^{7, 9}Be, unlike recombination with electrons. Our new nonresonant rate of the ^{7}Be recombination for m_{X} = 1000 GeV is more than six times larger than the existing rate. Moreover, we suggest a new important reaction for ^{9}Be production: the recombination of ^{7}Li and X ^{} followed by deuteron capture. We derive binding energies of X nuclei along with reaction rates and Q values. We then calculate BBN and find that the amount of ^{7}Be destruction depends significantly on the charge distribution of ^{7}Be. Finally, updated constraints on the initial abundance and the lifetime of the X ^{} are derived in the context of revised upper limits to the primordial ^{6}Li abundance. Parameter regions for the solution to the ^{7}Li problem and the primordial ^{9}Be abundances are revised.
 Publication:

The Astrophysical Journal Supplement Series
 Pub Date:
 September 2014
 DOI:
 10.1088/00670049/214/1/5
 arXiv:
 arXiv:1403.4156
 Bibcode:
 2014ApJS..214....5K
 Keywords:

 atomic processes;
 early universe;
 elementary particles;
 nuclear reactions;
 nucleosynthesis;
 abundances;
 primordial nucleosynthesis;
 stars: abundances;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 41 pages, 34 figures, 15 tables, errors fixed, abstract cut down, Figs. 2233 and Table 1 &