2025/01/17 by Kenta Hotokezaka, Hotokezaka, Kenta, Ryusuke Jinno +3 · 1 citation
Biochemistry, Genetics and Molecular Biology · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Fractal and DNA sequence analysis #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Phenomenology (hep-ph)
paper · pdf · doi:10.48550/arxiv.2501.10148
openalex publication_date 2025/01/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We point out a new effect on the freeze-out process of heavy particles induced by density perturbations in the early universe, which we call ``acoustically driven freeze-out.'' This beyond-linear effect is caused by the exponential decoupling of heavy particles from the thermal bath in the presence of density perturbations, and already at moderately large values δT / T = O (10-2) it cannot be captured by linear perturbation theory. We illustrate this effect with leptogenesis taking the decay and inverse decay of heavy neutrinos into account, and discuss its phenomenological implications. We found that perturbations always enhance the (spatially averaged) values of the final lepton asymmetry, and as a result, constraints on the mass of heavy neutrinos are found to be relaxed in the presence of perturbations.