http://arxiv.org/abs/1707.03852
A change in the fundamental constants of nature could stabilize $^8$Be against decay into two $^4$He nuclei. Coc et al. examined this effect on big bang nucleosynthesis as a function of $B_8$, the mass difference between two $^4$He nuclei and a single $^8$Be nucleus, and found no effects for $B_8 \le 100$ keV. Here we examine larger $B_8$ and also allow for a variation in the rate for $^4$He + $^4$He $\longrightarrow$ $^8$Be to determine the threshold for interesting effects. We find no change to standard big bang nucleosynthesis for $B_8 < 1$ MeV. For $B_8 \gtrsim 1$ MeV and a sufficiently large reaction rate, a significant fraction of $^4$He is burned into $^8$Be, which fissions back into $^4$He when $B_8$ assumes its present-day value, leaving the primordial $^4$He abundance unchanged. However, this sequestration of $^4$He results in a decrease in the primordial $^7$Li abundance. Primordial abundances of $^7$Li consistent with observationally-inferred values can be obtained for reaction rates similar to those calculated for the present-day (unbound $^8$Be) case. Even for the largest binding energies and largest reaction rates examined here, only a small fraction of $^8$Be is burned into heavier elements, consistent with earlier studies. There is no change in the predicted deuterium abundance for any model we examined.
R. Scherrer and R. Scherrer
Fri, 14 Jul 17
10/55
Comments: 7 pages, 2 figures