Search for π0 decays to invisible particles

NA62 Collaboration

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
103 Downloads (Pure)


The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.
Original languageEnglish
Article number201
Number of pages27
Issue number2
Publication statusPublished - 23 Feb 2021

Bibliographical note

Publisher Copyright:
© 2021, The Author(s).


  • Beyond Standard Model
  • Exotics
  • Fixed target experiments
  • Rare decay

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'Search for π0 decays to invisible particles'. Together they form a unique fingerprint.

Cite this