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Abstract:

We present a new measurement of the branching ratio R of the decay K L→ pi;±e∓ν, denoted as Ke3, relative to all charged KL decays with two tracks, based on data taken with the NA48 detector at the CERN SPS. We measure R=0.4978±0. 0035. From this we derive the Ke3 branching fraction and the weak coupling parameter |Vus| in the CKM matrix. We obtain |Vus|f+(0)=0. 2146±0.0016, where f+(0) is the vector form factor in the Ke3 decay. © 2004 Published by Elsevier B.V.

Abstract:

A time-of-flight system based on 46 multigap glass resistive plate chambers has operated for 2 years in the HARP experiment at the CERN PS. The system covers an area of 10m(2) and comprises 368 readout channels. Systematic checks of the RPC performance are presented as well as preliminary results on its particle identification capabilities. (C) 2004 Elsevier B.V. All rights reserved.

Abstract:

In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Ξ⁰→Λγ have been found with an estimated background of 58±8 events. From these events the Ξ⁰→Λγ decay asymmetry has been determined to α(Ξ⁰→Λγ)=-0.78±0.18stat±0.06 syst, which is the first evidence of a decay asymmetry in Ξ ⁰→Λγ. The branching fraction of the decay has been measured to be Br(Ξ⁰→Λγ)=(1.16±0.05 stat±0.06syst)×10^-3. © 2004 Elsevier B.V. All rights reserved.