Heavy neutral leptons beyond the BBN bound: probing the lepton asymmetry of the Universe

Kensuke Akita, Maksym Ovchynnikov, Vsevolod Syvolap

Hadronically decaying particles with lifetimes $\tau \gtrsim 0.02\mathrm{s}$ are excluded by Big Bang Nucleosynthesis almost independently of their abundance: the mesons from their decay…