Dark-sector physics in the search for the rare decays $K^{+}\to {\pi }^{+}\bar{\nu }\nu$ and $K_L\to {\pi }^0\bar{\nu }\nu$

Abstract

We compute the contribution of the decays $K_L\to {\pi }^{0}Q\bar{Q}$ and $K^{+}\to {\pi }^{+}Q\bar{Q}$, where $Q$ is a dark fermion of the dark sector, to the measured widths for the rare decays $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ and $K_L\to {\pi }^0\nu \bar{\nu }$. The recent experimental limit for $\Gamma (K^{+}\to {\pi }^{+}\nu \bar{\nu })$ from NA62 sets a new and very strict bound on the dark-sector parameters. A branching ratio for $K_L\to {\pi }^{0}Q\bar{Q}$ within the reach of the KOTO sensitivity is possible. The Grossman-Nir bound is weakened by the asymmetric effect of the different kinematic cuts enforced by the NA62 and KOTO experiments. This last feature holds true for all models where the decay into invisible states takes place through a light or massless intermediate state.

8 pages, 4 figures, minor text and figures improvements to agree with published version

References in corpus (5)

• Dark Matter and Dark Radiation
• Two-Loop Electroweak Corrections for the K -> pi nu anti-nu Decays
• Loophole in K --> pi nu nubar Search and New Weak Leptonic Forces
• Dark photons and resonant monophoton signatures in Higgs boson decays at the LHC
• FCNC decays of SM fermions into a dark photon

Cited by in corpus (13)

• The Dark Photon
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• Supernova Constraints on Dark Flavored Sectors
• Pair production of dark particles in meson decays
• Evading the Grossman-Nir bound with $\Delta I=3/2$ new physics
• Kaon decays shedding light on massless dark photons
• Three Exceptions to the Grossman-Nir Bound
• Imprint of a new light particle at KOTO?
• Magnetic-dipole corrections to $R_K$ and $R_{K^{\ast }}$ in the Standard Model and Dark Photon scenarios
• The Light Sgoldstino Phenomenology: Explanations for the Muon $(g-2)$ Deviation and KOTO Anomaly
• New Physics Searches at Kaon and Hyperon Factories
• Pionium as a source of false events in the $K\to \pi \nu \bar{\nu }$ decays