Evidence For CP Violation Research Articles

Search for CP violation in Zm Fττ

Using the 18.8 pb −1 of data accumulated at LEP in 1990 and 1991 with the ALEPH detector, a direct test of neutral current CP-invariance is performed by a search for CP-odd correlations in Z decays to τ pairs where both τ decay modes are identified. No evidence for CP-violation is observed. The weak dipole moment of the τ has been measured to be d τ ( m Z) = (1.3 ± 1.4 ± 0.1) × 10 −17 e·cm which results in an upper limit on the weak dipole moment of | d τ ( m Z)| ⩽ 3.7 × 10 −17 e·cm with 95% confidence level.

Possible Explanation of Anomalies in Neutral K Phenomena

THE experimental results usually interpreted as evidence for CP violation in neutral K decay have been found1 to be inconsistent with the values of all the relevant observables obtained from other measurements. In particular, either the KL–KS mass difference or the difference (δ2–δ0) between two pion–pion scattering phases, as determined from a phenomenological analysis1 of the former data, has an opposite sign from that obtained by independent measurements of these two quantities. (The measurements of the sign of the mass difference have been summarized in ref. 2, and the independent determination of the sign of (δ2–δ0) is backed by a considerable body of evidence; see ref. 3.)