Search for invisible decays of ${\pi }^0,\eta ,{\eta }^{\prime },K_S$ and $K_L$: A probe of new physics and tests using the Bell-Steinberger relation

Abstract

In the standard model the rate of the ${\pi }^0,\eta ,{\eta }^{\prime },K_S,K_L\to \nu \overline{\nu }$ decays is predicted to be extremely small. Therefore, observation of any of these mesons ($M^0$) decaying into an invisible final state would signal the presence of new physics. The Bell-Steinberger relation connects CP and CPT violation in the mass matrix to CP and CPT violation in all decay channels of neutral kaons. It is a powerful tool for testing CPT invariance in the $K^0-{\overline{K}}^0$ system, assuming that there are no significant undiscovered decay modes of either $K_S$ or $K_L$ which could contribute to the precision of the results. The $K_S,K_L\to invisible$ decays have never been tested and the question of how much these decays can influence the Bell-Steinberger analysis of the kaon system still remains open. In the present work we propose a new experiment to search for the $M^0\to invisible$ decays which aims at probing new physics and answering this question. The experiment utilizes high energy hadronic beams from the CERN SPS and the charge exchange reactions of pion or kaon on nucleons of an active target, e.g. ${\pi }^{-}(K^{-})+p\to M^0+n$, as a source of the well-tagged $M^0$s emitted with the beam energy. If the decay $M^0\to invisible$ exists, it could be observed by looking for an excess of events with a specific signature: the complete disappearance of the beam energy in the detector. This unique signal of $M^0\to invisible$ decays allows for searches of the decays $K_S,K_L\to invisible$ with a sensitivity in branching ratio Br$(K_S(K_L)\to invisible)\lesssim 10^{-8}(10^{-6})$, and ${\pi }^0,\eta ,{\eta }^{\prime }\to invisible$ decays with a sensitivity a few orders of magnitude beyond the present experimental limits. This experiment is complementary to the one recently proposed for the search for invisible decays of dark photons and fits well with the present kaon program at CERN.

10 pages, 5 figures. Revised version published in PRD, refs added

References in corpus (7)

• An Improved Limit on Invisible Decays of Positronium
• Experimental search for neutron - mirror neutron oscillations using storage of ultracold neutrons
• A direct experimental limit on neutron -- mirror neutron oscillations
• Search for the Invisible Decay of $\jpsi$ in $\psi (2S)\to \pi +{\pi }^{-}J/\psi$
• Determination of CP and CPT violation parameters in the neutral kaon system using the Bell-Steinberger relation and data from the KLOE experiment
• Search for $B^0$ decays to invisible final states at Belle
• Limit on the electric charge-nonconserving ${\mu }^{+}\to invisible$ decay

Cited by in corpus (15)

• The Dark Photon
• Muon g-2 and searches for a new leptophobic sub-GeV dark boson in a missing-energy experiment at CERN
• General neutrino interactions with sterile neutrinos in light of coherent neutrino-nucleus scattering and meson invisible decays
• Probing Invisible Vector Meson Decays with NA64 and LDMX
• Probing lepton number violating interactions in rare kaon decays
• Pair production of dark particles in meson decays
• Probing the braneworld hypothesis with a neutron-shining-through-a-wall experiment
• Rare hyperon decays with missing energy
• Neutron lifetime anomaly and mirror matter theory
• Note on invisible decays of light mesons
• Probing new physics with the kaon decays $K\to \pi \pi /E$
• Cosmological implications of the KOTO excess
• Search for $K_S^0$ invisible decays
• New Physics Searches at Kaon and Hyperon Factories
• Search for mirror hidden sector with neutral kaons at NA64