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Published on: November 15, 2013
Measurements of the Absolute Branching Fraction of the Semileptonic Decay Ξ^{-}→Λe^{-}ν[over ¯]_{e} and the Axial
M Ablikim1, M N Achasov2, P Adlarson3
1Institute of High Energy Physics, Beijing 100049, People's Republic of China.
Abstract:
Using (10 087±44)×10^{6} J/ψ events collected with the BESIII detector, we study the semileptonic decay Ξ^{-}→Λe^{-}ν[over ¯]_{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}±0.01_{syst}. These results are used to test various SU(3)-flavor effective models. Under the SU(3)-flavor 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.
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