Measurements of the Absolute Branching Fraction of the Semileptonic Decay \mathbfΞ^-→ Λe^- ν_e and the Axial Charge of the \mathbfΞ^-

2025/12/17 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +685
Physics and Astronomy · #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Neutrino Physics Research

paper · doi:10.48550/arxiv.2512.15273

Abstract

Using (10087±44)×10⁶ J/ψ events collected with the BESIII detector, we study the semileptonic decay Ξ^-→ Λe^- ν_e for the first time at an electron-positron collider. The absolute branching fraction is determined for the first time to be (3.60±0.40_stat±0.10_syst)×10^-4, which is 3.9 standard deviations below the world average. In addition, using an 11-dimensional angular analysis, the axial-vector to vector coupling g_av is determined to be 0.18±0.07_stat±0.02_syst. These results are used to test various SU(3)-flavour effective models. Under the SU(3)-flavour symmetry limit, the axial charge is found to be g_A^H = 0.22±0.08_stat±0.02_syst. Despite using only 5% of the statistics of previous experiments, this analysis achieves a comparable precision for the axial charge.

Related

• First Direct Measurement of the Absolute Branching Fraction of Σ⁺ → Λe⁺ ν_e
• Evidence for the semileptonic decays Λ_c⁺ → Σ^± π^∓ e⁺ ν_e
• Improved measurement of absolute branching fraction of the inclusive decay Λ_c⁺ → K_S⁰ X
• Search for the lepton number violating process Ξ−→Σ+e−e−+c.c
• Investigation of the semileptonic decays Ξ^(')_b→ Ξ^(')_cℓν_ℓ