The weak radiative decay Xi(o) -> 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(Xi(o) -> 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(Xi) Lambda(ee) = -0.8 +/- 0.2, consistent with that of Xi(o) -> Lambda gamma. The charge conjugate reaction (Xi(o)) over bar -> (Lambda) over bare(+)e(-) has also been observed. (c) 2007 Elsevier B.V.. All rights reserved.
First observation and branching fraction and decay parameter measurements of the weak radiative decay Xi(0)->Lambda e(+)e-
LAMANNA, GIANLUCA;COSTANTINI, FLAVIO;GIUDICI, SERGIO;SOZZI, MARCO STANISLAO;
2007-01-01
Abstract
The weak radiative decay Xi(o) -> 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(Xi(o) -> 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(Xi) Lambda(ee) = -0.8 +/- 0.2, consistent with that of Xi(o) -> Lambda gamma. The charge conjugate reaction (Xi(o)) over bar -> (Lambda) over bare(+)e(-) has also been observed. (c) 2007 Elsevier B.V.. All rights reserved.File in questo prodotto:
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