The standard model of big bang nucleosynthesis (BBN) relies on a nuclear reaction network
operating with thermal reactivities for Maxwellian plasma. In the primordial plasma,
however, a number of non-thermal processes triggered by energetic particles of
various origins can take place. In the present work we examine in-flight nuclear
reactions induced in the plasma by MeV protons generated in D(d, p)T and
3He(d, p)4He
fusions. We particularly focus on several low threshold endoergic processes. These are
reactions omitted in the standard network—proton-induced break-ups of loosely bound D,
7Li,
7Be nuclei—and
the 3H(p, n)3He
charge-exchange reaction important for the interconversion of
A = 3
nuclei in the early universe. It is found that the break-up processes
in the plasma take the form of Maxwellian processes at temperatures
T>70 keV, while in the lower temperature range they proceed as non-thermal reactions. It is shown that
at T<70 keV the in-flight reaction channels can enhance the break-up reactivities
by several orders of magnitude. The levels of these reactivities however
remain insufficiently high to affect BBN kinetics and change the standard
prediction of light element abundances. The abundances are found to be:
Yp = 0.2457,
D/H = 2.542 × 10−5,
3He/H = 1.004 × 10−5,
7Li/H = 4.444 × 10−10. Future steps in the study of non-thermal processes in the primordial plasma are briefly
discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.