First Direct Measurement of the Absolute Branching Fraction of Σ⁺ → Λe⁺ ν_e

2022/12/10 by BESIII Collaboration, M. Ablikim, Ablikim, M. +689
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies

paper · pdf · doi:10.48550/arxiv.2212.05296

openalex publication_date 2022/12/10 · openalex created_date 2022/12/26 · openalex updated_date 2026/07/28

Abstract

The first direct measurement of the absolute branching fraction of Σ⁺ → Λe⁺ ν_e is reported based on an e⁺e^- annihilation sample of (10087±44) × 10⁶ J/ψ events collected with the BESIII detector at √(s)=3.097 GeV. The branching fraction is determined to be \mathcal B(Σ⁺ → Λe⁺ ν_e) = [2.93±0.74(\rm stat) ± 0.13(\rm syst)]× 10^-5, which is the most precise measurement obtained in a single experiment to date and also the first result obtained at a collider experiment. Combining this result with the world average of \mathcal B(Σ^- → Λe^- ν_e) and the lifetimes of Σ^±, the ratio, \fracΓ(Σ^- → Λe^- ν_e)Γ(Σ⁺ → Λe⁺ ν_e), is determined to be 1.06 ± 0.28, which is within 1.8 standard deviations of the value expected in the absence of second-class currents that are forbidden in the Standard Model.

Related

• Measurement of branching fractions of Λ_c⁺ decays to Σ⁺ η and Σ⁺ η'
• Improved measurement of absolute branching fraction of the inclusive decay Λ_c⁺ → K_S⁰ X
• Measurement of the branching fraction of η→ μ⁺ μ^- and search for η→ e⁺ e^-
• Measurements of the Absolute Branching Fraction of the Semileptonic Decay \mathbfΞ^-→ Λe^- ν_e and the Axial Charge of the \mathbfΞ^-
• Evidence for the semileptonic decays Λ_c⁺ → Σ^± π^∓ e⁺ ν_e