CP violation andZ boson decays

We present a general discussion ofCP-violating effects in the following two and three body decays of theZ boson:Z→l ⁺ l ^?,Z→l ⁺ l ^?γ, wherel=e, μ, τ andZ→2 jets,Z→ 2 jets+γ, andZ→ 3 jets. Experimental observables sensitive toCP violation in these decays are discussed systematically for the case that polarizations of final state particles are not observed. It is shown that the standard model predicts only extremely smallCP-violating effects for the above decays. PossibleCP-violating interactions beyond the standard model are parametrized in terms of aCP-odd effective Lagrangian containing coupling constants proportional to Λ _P ^-1 and Λ _P ^-2 . Here Λ _CP is the mass scale associated with the assumed new interactions. We give estimates of the bounds obtainable for Λ _CP in experiments at LEP1.     

CP violation and top quark decays

We investigate how to testCP invariance in the weak decay of top quarks. A prediction ofCP violation from the Standard Model is made by an explicit calculation. The effect is very small as expected. We then use a form factor approach to parametrize possible new interactions ofCP violation. The differences between the form factor approach and an effective Lagrangian approach are discussed. The sensitivity of ourCP-odd observables to the form factors is estimated.     

CP violation in radiative Z decays

We propose to test the CP symmetry in the reactions Z → μ⁺μ^?γ and Z → τ⁺τ^?γ. The experimental analysis of angular correlations allows to determine a set of effective couplings: the electric and weak dipole moments of the muon and the tau lepton, and in particular chirality conserving 4-particle couplings, all of which can be induced by CP-violation in renormalizable theories of electroweak interactions beyond the Standard Model. We update an indirect bound on the weak dipole moment of the muon.     

Direct CP violation in hadronic B decays

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on k _T factorization, using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.     

D-meson lifetimes and decays

We discuss the theoretical implications of having the D⁺ lifetime be much greater than that of the D⁰. A consistent phenomenology of D-decay obtains if one assumes sextet dominance and strong color clustering.     

Possibility of CP violation in the cascade non-leptonic decays

There is more than one parameter expressing CP violation in the non-leptonic hyperon decays. The recent experimental results provide us with indications that CP conservation may not be valid for the Ξ decays. Especially for the Ξ dacays this is not due to the deviations from the exact ΔI=1/2 rule.     

Spontaneous CP violation and neutral B meson decays

A model in which CP is spontaneously broken is described; it solves the strong CP problem and provides an additional mechanism for weak CP violation. This is the aspon model. Application to B decays leads to predictions for CP asymmetries much smaller than expected from the KM mechanism of explicit CP breaking.     

The discovery of CP violation in B-meson decays

We present the KEK B-factory project, which discovered CP violation in B-meson decays and proved that the Kobayashi-Maskawa theory correctly explains CP violation in meson decays.(Communicated by Toshimitsu YAMAZAKI, M.J.A.).     

CP violation for neutral charmed meson decays into CP eigenstates

The CP asymmetries for the decays of the neutral charmed meson into CP eigenstates are carefully studied. Formulas and numerical results are presented. The impact on experiments is briefly discussed.