Search for the lepton number violating decay η→ π⁺π⁺e^-e^- + c.c. via J/ψ→ϕη

2025/09/26 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +689
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2509.21921

Abstract

Based on a sample of (10.087± 0.044)× 10⁹ J/ψ events collected by the BESIII detector at the BEPCII collider, we perform the first search for the lepton number violating decay η→ π⁺π⁺ e^-e^- + c.c. No signal is found, and an upper limit on the branching fraction of η→ π⁺π⁺ e^-e^- + c.c. is set to be 4.6 × 10^-6 at the 90% confidence level.

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