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

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.

arXiv comment4 pages, no figures, compatible with the published version

References in corpus (21)

• Two-Loop Electroweak Corrections for the K -> pi nu anti-nu Decays
• $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ and $K_L\to {\pi }^0\nu \bar{\nu }$ in the Standard Model: Status and Perspectives
• The Beam and detector of the NA62 experiment at CERN
• Search for $K_L\to {\pi }^0\nu \overline{\nu }$ and $K_L\to {\pi }^0{X}^0$ Decays at the J-PARC KOTO Experiment
• First measurement of the ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Observation of a cusp-like structure in the pizero-pizero invariant mass distribution from K+- ==> pi+- pizero pizero decay and determination of the pi-pi scattering lengths
• Explaining $(g-2{)}_{\mu ,e}$, the KOTO anomaly and the MiniBooNE excess in an extended Higgs model with sterile neutrinos
• Light Scalars and the KOTO Anomaly
• New physics implications of recent search for $K_L\to {\pi }^0\nu \bar{\nu }$ at KOTO
• First search for $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ using the decay-in-flight technique
• Determination of $\pi \pi$ scattering lengths from measurement of ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Constraints on long-lived light scalars with flavor-changing couplings and the KOTO anomaly
• An investigation of the very rare $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ decay
• Some implications of meson dominance in weak interactions
• A new search for the $K_L\to {\pi }^0\nu \overline{\nu }$ and $K_L\to {\pi }^0{X}^0$ decays
• Dark-sector physics in the search for the rare decays $K^{+}\to {\pi }^{+}\bar{\nu }\nu$ and $K_L\to {\pi }^0\bar{\nu }\nu$
• KLEVER: An experiment to measure BR($K_L\to {\pi }^0\nu \bar{\nu }$) at the CERN SPS
• Imprint of a new light particle at KOTO?
• First measurement of a long-lived ${\pi }^{+}{\pi }^{-}$ atom lifetime
• The Light Sgoldstino Phenomenology: Explanations for the Muon $(g-2)$ Deviation and KOTO Anomaly
• Possible manifestation of the 2p pionium in particle physics processes