The Leptogenesis Mass Scale Against the Temperature Ceiling of a Torsion Bounce

Thermal leptogenesis requires heavy Majorana neutrinos, and an old question is whether the temperature needed to produce them is available in a cosmology with a maximum density. This paper computes the temperature ceiling implied by a torsion-regulated bounce with density ceiling 9.72e57 kg per cubic metre and compares it with the minimum heavy-neutrino mass from the Davidson-Ibarra bound. The ceiling is T_max = 3.28e+22 K, or 2.82e+09 GeV. Reproducing the observed asymmetry at efficiency 0.1 requires a CP asymmetry of 9.29e-08, which the Davidson-Ibarra bound converts into a minimum mass M1 = 9.42e+08 GeV; at M1 = 1e10 GeV the largest allowed CP asymmetry is 9.86e-07. The ceiling exceeds the minimum scale by a factor of 3.00e+00, so the bounce does not obstruct thermal leptogenesis: the required temperatures are reached, with enormous headroom, on both sides of the bounce. Computed from stated assumptions, not measured.