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arXiv · 2006.02969

Pionium as a source of false events in the $K\to\pi\nu\bar\nu$ decays

Peter Lichard
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Abstract

We suggest that the decay modes of kaons with a pion and a pionium ($\pi^+\pi^-$ atom) in the final state can constitute a not yet considered background to the very rare decay $K\to\pi\nu\bar\nu$. In fact, a part of pioniums may escape the decay region before decaying into two $\pi^0$s (or to $\pi^0\pi^0\gamma$ in the case of excited pionium). To illustrate the importance of this background, we show that it may even explain, under some assumptions, the unexpected $K_L$ decay events that appeared in the KOTO experiment.

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Peter Lichard. 2020-06-04. Pionium as a source of false events in the $K\to\pi\nu\bar\nu$ decays. https://doi.org/10.1103/physrevd.102.113005

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