We explore a nuclear physics resolution to the discrepancy between the predicted standard big-bang nucleosynthesis (BBN) abundance of Li7 and its observational determination in metal-poor stars. The theoretical Li7 abundance is 3-4 times greater than the observational values, assuming the baryon-to-photon ratio, ηwmap, determined by WMAP. The Li7 problem could be resolved within the standard BBN picture if additional destruction of A=7 isotopes occurs due to new nuclear reaction channels or upward corrections to existing channels. This could be achieved via missed resonant nuclear reactions, which is the possibility we consider here. We find some potential candidate resonances which can solve the lithium problem and specify their required resonant energies and widths. For example, a 1 - or 2- excited state of C10 sitting at approximately 15.0 MeV above its ground state with an effective width of order 10 keV could resolve the Li7 problem; the existence of this excited state needs experimental verification. Other examples using known states include Be7+t→B10(18.80MeV) , and Be7+d→B9(16.71MeV). For all of these states, a large channel radius (a>10fm) is needed to give sufficiently large widths. Experimental determination of these reaction strengths is needed to rule out or confirm these nuclear physics solutions to the lithium problem.
|Physical Review D - Particles, Fields, Gravitation and Cosmology
|Published - Mar 23 2011
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)