Search for the lepton number violating process J/ψ→ K⁺K⁺e^-e^- +c.c.

2025/07/09 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +689
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2507.06872

Abstract

Based on (10087± 44)×10⁶ J/ψ events collected with the BESIII detector, we search for the lepton number violating decay J/ψ→ K⁺K⁺e^-e^- + c.c. for the first time. The upper limit on the branching fraction of this decay is set to be 2.1 × 10^-9 at the 90% confidence level with a frequentist method. This is the first search for J/ψ decays with the lepton number change by two, offering valuable insights into the underlying physical processes.

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