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arXiv · hep-ex/0703023

First observation and branching fraction and decay parameter measurements of the weak radiative decay Xi0 --> Lambda e+e-

NA48 Collaboration
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Abstract

The weak radiative decay Xi0 --> Lambda e+e- has been detected for the first time. We find 412 candidates in the signal region, with an estimated background of 15 +/- 5 events. We determine the branching fraction B(Xi0 --> Lambda e+e-) = [7.6 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(norm)] x 10^{-6}, consistent with an internal bremsstrahlung process, and the decay asymmetry parameter alpha_{XiLambdaee} = -0.8 +/- 0.2, consistent with that of Xi0 --> Lambda gamma. The charge conjugate reaction Xi0_bar --> Lambda_bar e+e- has also been observed.

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NA48 Collaboration. 2007-05-01. First observation and branching fraction and decay parameter measurements of the weak radiative decay Xi0 --> Lambda e+e-. https://doi.org/10.1016/j.physletb.2007.04.066

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