Sterile-Neutrino Mixing Bounds from Bounce-Era Production

This paper computes a specific neutrino quantity in a cosmology whose collapse is regulated by a maximum density, the Aldred Limit evaluated on its neutron branch at 9.72e+54 grams per cubic centimetre. A light sterile neutrino mixed with the active states would be produced by oscillations in the early universe, and its abundance is bounded by the effective number of relativistic species and by structure formation. The production peaks at a temperature set by the mass splitting, well above active decoupling. The calculation gives the following headline values: dm2_eV2 = 1.0, reference_sin2_2theta = 1e-07, T_peak_MeV = 133.0, rho_ratio_at_peak = 2.5684759685487404e-42, fractional_rate_change = 2.5684759685487404e-42. Each value is obtained from stated assumptions by the deposited script and is compared with published observational values where such values exist. Where the computed frame effect is far below observational reach, that negative result is stated plainly rather than softened. This study is simulated and computed from stated assumptions; it is not a measurement.