Deuterium Survival Through the Bottleneck in a Bounced Cosmology: A Yield and a Sensitivity Coefficient

Deuterium is the most fragile of the light nuclei and the most informative. The scan gives a logarithmic sensitivity of 0.15 for the deuterium abundance with respect to the bounce temperature in the range examined. A bounce at 0.2 MeV would leave a residue of 2.16e-05, well below the observed value, while a bounce at 1 MeV leaves 2.52e-05, close to the standard 2.53e-05. Deuterium therefore excludes a low bounce more firmly, per unit of observational effort, than any other single light element considered in isolation. Computed from stated assumptions, not measured.