2003/12/15 by James P. Kneller, Gail C. McLaughlin, G. C. McLaughlin · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Particle physics theoretical and experimental studies #astro-ph #nucl-th
paper · pdf · doi:10.1103/physrevd.70.043512
published as Phys.Rev. D70 (2004) 043512
arxiv created 2003/12/15 · openalex publication_date 2004/08/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have examined the effects of a bound dineutron 2n upon big bang nucleosynthesis (BBN) as a function of its binding energy B_2n. We find a weakly bound dineutron has little impact but as B_2n increases its presence begins to alter the flow of free nucleons to helium-4. Because of this disruption, and in the absence of changes to other binding energies or fundamental constants, BBN sets a reliable upper limit of B_2n\ensuremath\lesssim2.5MeV in order to maintain the agreement with the observations of the primordial helium-4 mass fraction and D/H abundance. We also consider simultaneous variations in B_2n and the deuteron binding energy BD using a simplified BBN calculation. We demonstrate that only when BD is very close to 1.7 MeV does the B_2n upper limit increase to 3.5 MeV, a value set by incompatibility of an observed primordial A=2 abundance with the decay of deuterons.