J. Derre

An EPR experiment testing the non-separability of the wave function

Abstract The EPR-type strangeness correlation in the K0 K 0 system produced in the reaction p p → K 0 K 0 at rest has been tested using the CPLEAR detector. The strangeness was tagged via strong interaction with absorbers away from the creation point. The results are consistent with the QM non-separability of the wave function and exclude a spontaneous wave-function factorisation at creation (CL >99.99%).

A determination of the CP violation parameter η+- from the decay of strangeness-tagged neutral kaons

LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

Search for CP violation in the decay of tagged K0 and K0 to π0π0π0

Abstract The CPLEAR experiment measured the eigentime-dependent asymmetry in the rates of initially tagged K 0 and K 0 decaying to π 0 π 0 π 0 in order to study the interference between the CP-violating K S and the CP-conserving K L decay amplitudes. Without assuming CPT invariance, we obtain for the CP-violation parameter η 000 the values Re( η 000 )=0.18±0.14 stat. ±0.06 syst. and Im( η 000 )=0.15±0.20 stat. ±0.03 syst. . Requiring Re( η 000 ) to be equal to Re(ϵ) we obtain Im( η 000 )=−0.05±0.12 stat. ±0.05 syst. . The corresponding upper limit for the branching ratio of the K S →π 0 π 0 π 0 decay is deduced to be B K S →π 0 π 0 π 0 −5 at the 90% confidence level.

\(\mathrm{\cal T}\)-violation and \(\mathrm{\cal CPT}\)-invariance measurements in the CPLEAR experiment: a detailed description of the analysis of neutral-kaon decays to \(\mathrme \pi \nu\)

Abstract. A detailed description of the analysis of neutral kaons decaying to

Evaluation of the phase of the CP violation parameter η+− and the KL - KS mass difference from a correlation analysis of different experiments

\mathrme \pi \nu

Measurement of the energy dependence of the form factor f+ in K0e3 decay

is given, based on the complete set of data collected with the CPLEAR experiment. Using a novel approach involving initially strangeness-tagged

CPLEAR results on the CP parameters of neutral kaons decaying to π+π−π0

\mathrm{K^0}

Experimental measurement of the KSKSKSKL ratio in antiproton annihilations at rest in gaseous hydrogen at 15 and 27 bar

and

An upper limit for the branching ratio of the decay K

\mathrm{\overline{K}}{}^0

_S \rightarrow e^+e^-

, time-dependent decay-rate asymmetries were measured. These asymmetries enabled