We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The Neutron Mean Life and Big Bang Nucleosynthesis.
- Authors
Yeh, Tsung-Han; Olive, Keith A.; Fields, Brian D.
- Abstract
We explore the effect of neutron lifetime and its uncertainty on standard big bang nucleosynthesis (BBN). BBN describes the cosmic production of the light nuclides, 1 H , D, 3 H + 3 He , 4 He , and 7 Li + 7 Be , in the first minutes of cosmic time. The neutron mean life τ n has two roles in modern BBN calculations: (1) it normalizes the matrix element for weak n ↔ p interconversions, and (2) it sets the rate of free neutron decay after the weak interactions freeze-out. We review the history of the interplay between τ n measurements and BBN, and present a study of the sensitivity of the light element abundances to the modern neutron lifetime measurements. We find that τ n uncertainties dominate the predicted 4 He error budget, but these theory errors remain smaller than the uncertainties in 4 He observations, even with the dispersion in recent neutron lifetime measurements. For the other light element predictions, τ n contributes negligibly to their error budget. Turning the problem around, we combine present BBN and cosmic microwave background (CMB) determinations of the cosmic baryon density to predict a "cosmologically preferred" mean life of τ n (BBN + CMB) = 870 ± 16 s , which is consistent with experimental mean life determinations. We show that if future astronomical and cosmological helium observations can reach an uncertainty of σ obs (Y p) = 0.001 in the 4 He mass fraction Y p , this could begin to discriminate between the mean life determinations.
- Subjects
NUCLEOSYNTHESIS; NEUTRONS; NEUTRON measurement; COSMIC background radiation; ERROR analysis in mathematics; LIGHT elements
- Publication
Universe (2218-1997), 2023, Vol 9, Issue 4, p183
- ISSN
2218-1997
- Publication type
Article
- DOI
10.3390/universe9040183