Experimental results on KLK_L decays

Recent measurements by the NA48 at CERN of selected $K_L$ decays are presented. These are the branching ratios and form factors for channels K_L\to \pi^{\pm}\pi^0\e^{\mp}\nu_e (final result), $K_L\to\pi^{\pm}e^{\mp}\nu_e$ and $K_L\to e^+e^-e^+e^-$ (preliminary results).Comment: 4 pages, 5 figures, talk given at QCD'04 Conference, Montpellier, France, 5-9 July 200

Measuring gravitational effects on antimatter in space

A direct measurement of the gravitational acceleration of antimatter has never been performed to date. Recently, such an experiment has been proposed, using antihydrogen with an atom interferometer and an antihydrogen confinament has been realized at CERN. In alternative we propose an experimental test of the gravitational interaction with antimatter by measuring the branching fraction of the CP violating decay of KL in space. In fact, even if the theoretical Standard Model explains the CPV with the presence of pure phase in the KMC Kobaiashi-Maskava-Cabibbo matrix, ample room is left for contributions by other interactions and forces to generate CPV in the mixing of the neutral K and B mesons. Gravitation is a good candidate and we show that at the altitude of the International Space Station, gravitational effects may change the level of CP violation such that a 5 sigma discrimination may be obtained by collecting the KL produced by the cosmic proton flux within a few years

Determination of the T- and CPT-violation parameters in the neutral-kaon system using the Bell-Steinberger relation and data from CPLEAR

Data from the CPLEAR experiment, together with the most recent world averages for some of the neutral-kaon parameters, were constrained with the Bell-Steinberger (or unitarity) relation, allowing the T-violation parameter Re(epsilon) and the CPT-violation parameter Im(delta) of the neutral-kaon mixing matrix to be determined with an increased accuracy: Re(epsilon)=(164.9 +/- 2.5) x 10(-5), Im(delta)=(2.4 +/- 5.0) x 10(-5). Moreover, the constraint allows the CM-violation parameter for the neutral-kaon semileptonic decays, Re(), to be determined for the first time. The Delta S not equal Delta Q parameters Re(x_) and Im(x(+)) are given with an increased accuracy. The quantity Re(y + x_), which enters the T-violation CPLEAR asymmetry previously published, is determined to be (- 0.2 +/- 0.3) x 10(-3). The value obtained for Re(delta) is in agreement with the one resulting from a previous unconstrained fit and has a slightly smaller error. (C) 1999 Elsevier Science B.V, All rights reserved.Physics Letters

Tests of the Equivalence Principle with neutral kaons

We test the Principle of Equivalence for particles and antiparticles, using CPLEAR data on tagged K-0 and (K) over bar(0) decays into pi(+) pi(-). For the first time, we search for possible annual, monthly and diurnal modulations of the observables \eta(+-)\ and phi(+-), that could be correlated with variations in astrophysical potentials. Within the accuracy of CPLEAR, the measured values of \eta(+-)\ and phi(+-) are found not to be correlated with changes of the gravitational potential. We analyze data assuming effective scalar, vector and tensor interactions, and we conclude that the Principle of Equivalence between particles and antiparticles holds to a level of 6.5, 4.3 and 1.8 X 10(-9), respectively, for scalar, vector and tensor potentials originating from the Sun with a range much greater than the distance Earth-Sun. We also study energy-dependent effects that might arise from vector or tensor interactions. Finally, we compile upper limits on the gravitational coupling difference between K-0 and (K) over bar(0) as a function of the scalar, vector and tensor interaction range. (C) 1999 Elsevier Science B.V. All rights reserved.Physics Letters

Measurement of the K-L-K-S mass difference using semileptonic decays of tagged neutral kaons

We report on a new measurement of the K-L-K-S mass difference Delta m using the CPLEAR full data sample of neutral-kaon decays to e pi nu. The result is Delta m = (0.5295 +/- 0.0020(stat) +/- 0.0003(syst)) X 10(10) (h) over bar/s. It includes earlier data reported in R. Adler et al., CPLEAR Collaboration, Phys. Lett. B 363 (1995) 237. A measurement of the Delta S = Delta Q violating parameter Re(x) is also obtained. (C) 1998 Elsevier Science B.V. All rights reserved.Physics Letters

A determination of the CP violation parameter eta(+-) from the decay of strangeness-tagged neutral kaons

We report a measurement of the CP violation parameter eta(+-) from the time-dependent asymmetry between the decay rates of initially tagged K-0 and (K) over bar(0). The results are based on the complete data sample collected by the CPLEAR collaboration. With Delta m = (530.1 +/- 1.4) X 10(7)(h) over bar s(-1) and tau(S) = (89.34 +/- 0.08) ps, the values obtained are \eta(+-)\ = (2.264 +/- 0.023(stat) +/- 0.026(syst) +/- 0.007 tau(s)) x 10(-3) and phi(+-) = 43.19 degrees +/- 0.53(stat)degrees +/- 0.28(syst)degrees + 0.42(Delta m)degrees. (C) 1999 Published by Elsevier Science B.V. All rights reserved.Physics Letters

Contribution of CPLEAR to the physics of the neutral-kaon system

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(delta), from the Bell-Steinberger relation, with a precision. of 10(-5) and Re(delta) 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) over bar(0) It to be equal within 10(-18) GeV. In the limit of CPT invariance in the neutral kaon decays, the K-0 and (K) over bar(0) masses are equal within 10(-19) GeV

Pion correlations and resonance effects in (p)over-barp annihilation at rest

We study pi pi correlations in the exclusive reactions (p) over bar p –> 2 pi(+)2 pi(-) and (p) over bar p –> 2 pi(+)2 pi(-)pi(0) at rest with complete reconstruction of the kinematics for each event. A new analysis technique has been developed which is model independent. With this new technique, which relies on double-differential distributions, no reference sample is needed to extract the correlation signal. The correlations are studied as a function of the four-pion invariant mass

Discrete symmetries with neutral mesons

Symmetries, and Symmetry Breakings, in the Laws of Physics play a crucial role in Fundamental Science. Parity and Charge Conjugation Violations prompted the consideration of Chiral Fields in the construction of the Standard Model, whereas CP-Violation needed at least three families of Quarks leading to Flavour Physics. In this Lecture I discuss the Conceptual Basis and the present experimental results for a Direct Evidence of Separate Reversal-in-Time T, CP and CPT Genuine Asymmetries in Decaying Particles like Neutral Meson Transitions, using Quantum Entanglement and the Decay as a Filtering Measurement. The eight transitions associated to the Flavour-CP eigenstate decay products of entangled neutral mesons have demonstrated with impressive significance a separate evidence of TRV and CPV in Bd-physics, whereas a CPTV asymmetry shows a 2σ effect interpreted as an upper limit. Novel CPTV observables are discussed for K physics at KLOE-2, including the difference between the semileptonic asymmetries from KL and KS, the ratios of double decay rate Intensities to Flavour-CP eigenstate decay products and the ω-effect. Their observation would lead to a change of paradigm beyond Quantum Field Theory, however there is nothing in Quantum Mechanics forbidding CPTV