We report the results of the CPLEAR experiment on CP-, T- and CPT-symmetries in the neutral kaon system. CP-violation parameters are given for different decay channels. For the first time T-violation ...is measured by a direct method using semileptonic decays. The CPT symmetry in the kaons decays is tested through the parameters Im(
δ), from the Bell-Steinberger relation, with a precision of 10
−5 and Re(
δ) with a precision of a few 10
−4 (two order of magnitude better than the previous measurement). These two measurements allow us to bound the difference in mass and width of K
0 and ¯K
0 to be equal within 10
−18 GeV. In the limit of CPT invariance in the neutral kaon decays, the K
0 and ¯K
0 masses are equal within 10
−19 GeV.
The CPLEAR experiment uses tagged K
0 and K̄
0 produced in pp̄ annihilation at rest to measure CP-, T- and CPT-violation parameters in the neutral kaon system. The results of these measurements and ...some implications are reported.
A measurement of the branching ratio for K
s → e
+e
− decay was performed with the CPLEAR detector at LEAR. Full event reconstruction together with calorimeter e/π separation allowed for powerful ...background rejection and high signal acceptance. Analysis of data taken up to 1994 yields the result: Br(K
s → e
+e
−) < 4.2 · 10
−7 (90 % CL).
Measurement of η +− with the CPLEAR experiment Adler, R.; Alhalel, T.; Angelopoulos, A. ...
Nuclear physics. Section B, Proceedings supplement,
1997, Letnik:
56, Številka:
1
Journal Article
The CPLEAR experiment at CERN uses time-dependent decay-rate asymmetries between K
0 and K̄
0 to measure
η
+−. The analysis and the systematic errors are discussed. The preliminary results from all ...our data are
φ
+− = 43.5
0
± 0.5
0
stat ± 0.5
syst ± 0.4
Δm and |
η+−| = (2.316 ± 0.025
stat ± 0.028
syst ± 0.009
τS
) × 10
−3. The dominant part in the systematic error of
φ
+− is due to the regeneration correction. A dedicated experiment was performed to reduce this error considerably.
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