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arXiv · 2008.00749

Improved BBN constraints on Heavy Neutral Leptons

Alexey Boyarsky·Maksym Ovchynnikov·Oleg Ruchayskiy·Vsevolod Syvolap
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Abstract

We constrain the lifetime of thermally produced Heavy Neutral Leptons (HNLs) from primordial nucleosynthesis. We show that even a small fraction of mesons present in the primordial plasma leads to the over-production of the primordial helium. This puts an upper bound on the lifetime of HNLs $\tau_{N}<0.02$ s for masses $m_{N}>m_{\pi}$ (as compared to 0.1 s reported previously). In combination with accelerator searches, this allows us to put a new lower bound on the HNLs masses and defining the "bottom line" for HNL searches at the future Intensity Frontier experiments.

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Alexey Boyarsky, Maksym Ovchynnikov, Oleg Ruchayskiy, Vsevolod Syvolap. 2020-08-03. Improved BBN constraints on Heavy Neutral Leptons. https://doi.org/10.1103/physrevd.104.023517

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