Searches for lepton number violation and resonances in the K→πμμ decays

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Colleges, School and Institutes


The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003–2004. A new upper limit on the rate of the lepton number violating decay K±→π∓μ±μ± is reported: B(K±→π∓μ±μ±)<8.6×10−11 at 90% CL. Searches for two-body resonances X in K±→πμμ decays (such as heavy neutral leptons N4 and inflatonsχ) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K±→μ±N4) B(N4→πμ) and B(K±→π±X) B(X→μ+μ−) for ranges of assumed resonance masses and lifetimes. The limits are in the (10−11, 10−9) range for resonance lifetimes below 100 ps.


Original languageEnglish
Pages (from-to)67–76
Number of pages10
JournalPhysics Letters B
Early online date18 Mar 2017
Publication statusPublished - 10 Jun 2017