Search for the double Dalitz decays η/η' → e⁺e^-μ⁺μ^- and η' → μ⁺μ^-μ⁺μ^-

2024/12/27 by BESIII Collaboration, M. Ablikim, М. Н. Ачасов +747
Physics and Astronomy · Computer Science · #Particle physics theoretical and experimental studies #Computational Physics and Python Applications #Quantum Chromodynamics and Particle Interactions

paper · pdf · doi:10.48550/arxiv.2412.19702

Abstract

Using a data sample of (10087 ± 44) × 10⁶ J/ψ events collected with the BESIII detector, we search for the decays η/η'→ e⁺e^-μ⁺μ^- and η' → μ⁺μ^-μ⁺μ^- via the radiative decays J/ψ→γη/γη'. No excess of events over expected background is observed for any of the decays of interest. At 90% confidence level, we report the first upper limits on the branching fractions of η' → e⁺e^-μ⁺μ^- and η' → μ⁺μ^-μ⁺μ^- to be 1.75 × 10^-6 and 5.28 × 10^-7, respectively. In addition, we set an upper limit on the branching fraction of η→ e⁺e^-μ⁺μ^- to be 6.88 × 10^-6, which improves the previous result by about two orders of magnitude.

Related

• Measurement of the branching fraction of η→ μ⁺ μ^- and search for η→ e⁺ e^-
• Observation of the decay J/ψ→ e⁺ e^- η(1405) with η(1405) → π⁰ f₀(980)
• Study of η→π⁺π^-l⁺l^-
• Improved measurement of the decays η' → π⁺π^-π⁺⁽⁰⁾π^-(0) and search for the rare decay η' → 4π⁰
• Measurement of the Electromagnetic Transition Form-factors in the decays η'→π⁺π^-l⁺l^-