Abstract
The NA62 experiment at the CERN SPS provides unique opportunity to study rare and forbidden decays of K + mesons. Using the data collected in 2017 a search for the lepton number violating decays K + → π − µ + µ + and K + → π − e + e + has been performed. New upper limits on the branching ratio have been obtained: 4.2×10−11 for the muon and 2.2×10−10 for the electron mode (90% confidence level). These results improve the existing limits by factors of 2 and 3 respectively.
Highlights
A lot of scenarios beyond the Standard Model (SM) allow for lepton flavor violating (LFV) and lepton number violating (LNV) processes
The beam particle identification is performed by a Cherenkov differential counter (KTAG), while a Ring Imaging Cherenkov (RICH) detector is used for the separation of pions and muons produced in kaon decays, as well as for the precise timing
The event selection starts with the requirement on the presence of a good quality 3-track vertex reconstructed in the fiducial volume: 114 m < Zvtx < 180 m for the muon mode (105 m < Zvtx < 180 m for the electron mode) and the total charge equal to +1 e
Summary
A lot of scenarios beyond the Standard Model (SM) allow for lepton flavor violating (LFV) and lepton number violating (LNV) processes. The best upper limits obtained so far come from the CERN NA48/2 experiment for the muon mode [3] (BR(K+ → π−μ+μ+) < 8.6 × 10−11) and from BNL E865 for the electron mode [4] (BR(K+ → π−e+e+) < 6.4 × 10−10).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
