科研之友
微信
新浪微博
Facebook
分享链接
摘要
We have studied big bang nucleosynthesis in the presence of regions of antimatter. Depending on the distance scale of the antimatter region, and thus the epoch of their annihilation, the amount of antimatter in the early universe is constrained by the observed abundances. Small regions, which annihilate after weak freezeout but before nucleosynthesis, lead to a reduction in the He-4 yield, because of neutron annihilation. Large regions, which annihilate after nucleosynthesis, lead to an increased He-3 yield. Deuterium production is also affected but not as much. The three most important production mechanisms of He-3 are (1) photodisintegration of He-4 by the annihilation radiation, (2) (p) over bar He-4 annihilation, and (3) (n) over bar He-4 annihilation by "secondary" antineutrons produced in (4)(He) over bar annihilation. Although (p) over bar He-4 annihilation produces more He-3 than the secondary (n) over bar He-4 annihilation, the products of the latter survive later annihilation much better, since they are distributed further away from the annihilation zone. Our results are in qualitative agreement with similar work by Rehm and Jedamzik, but we get a larger He-3 yield.
- 出版日期2000-11-15
