TY - JOUR

T1 - Search for the double Dalitz decays η / η ′ → e + e − μ + μ − and η ′ → μ + μ − μ + μ −

AU - BESIII Collaboration

AU - Ачасов, Михаил Николаевич

AU - Мучной, Николай Юрьевич

AU - Николаев, Иван Борисович

PY - 2025/3/10

Y1 - 2025/3/10

N2 - Using a data sample of ( 10087 ± 44 ) × 10 6 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 → γ η / γ η ′ . 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.

AB - Using a data sample of ( 10087 ± 44 ) × 10 6 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 → γ η / γ η ′ . 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.

UR - https://www.mendeley.com/catalogue/c76c9603-6ec7-305f-8ba5-369802a49704/

U2 - 10.1103/physrevd.111.052002

DO - 10.1103/physrevd.111.052002

M3 - Article

VL - 111

SP - 052002

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 5

ER -