We analyze in the four-generation model the first measurement of the branching ratio of rare kaon decay K + → π + νν, along with the other processes of

No abstract

Due to the large mass of top quark, CP violation in the top-quark decay is sensitive to the interactions mediated by Higgs bosons. We consider CP violation in t → W + b decay by calculating consistently in unitary gauge the CP-violating up-down asymmetry of the leptons from W boson decays in t → W + b, defined by Grzadkowski and Gunion, in the two-Higgs doublet model with CP-violating neutral sector. The asymmetry is shown to be at most of the order of (1 − 3) × 10 −4 for tan β = 1.0, where tan β is the ratio of vacuum expectation values for the two neutral Higgs bosons.1

We investigate the effects of CP violation in nonleptonic decays of neutral B mesons (Bd, Bs) in the Kobayashi-Maskawa model through the quark exchange diagram in terms of the Wolfenstein matrix. In our calculation, we use the new data of mixing parameter xd= 0.70±0.13 which is derived from ARGUS and CLEO measurements and the new data on the branching ratio for Bd meson. We obtain the results that CP violating asymmetries for Bd→D+D−, π+π− and K+K− reach about 50% and the number of [Formula: see text] quark pairs needed to detect the asymmetry is O(106~107) at 3σ level, and the asymmetries for [Formula: see text], D−π+, D0π0 and D+π− reach the order of 20% and the number of [Formula: see text] pairs is O(108). Therefore, we may conclude that the CP violation for these decay modes is possibly observable at the present stage. The effects of fourth generation quarks on CP violation are also studied.

We investigate the CP violation effect and the matter effect in the long-baseline neutrino oscillations in the four-neutrino model with the mass scheme of the two pairs of two close masses separated by a gap of the order of 1 eV by using the constraints on the mixing matrix derived from the solar neutrino deficit, atmospheric neutrino anomaly, LSND experiments, and the other terrestrial neutrino oscillation experiments. We also use the results of the combined analyses by Gonzalez-Garcia, Maltoni, and Peña-Garay of the solutions to the solar and atmospheric neutrino problems with the recent SNO solar neutrino data. For the solution of close-to-active solar neutrino oscillations plus close-to-sterile atmospheric neutrino oscillations, the pure CP violation part of the oscillation probability difference between the CP-conjugate channels could get as large as 0.10-0.25 in the neutrino energy range of Eϭ6 -15 GeV at the baseline Lϭ730 km for → oscillation and the matter effect is at the 8 -15 % level of the pure CP violation effect, while for the solution of near-pure-sterile solar neutrino oscillations plus near-pure-active atmospheric neutrino oscillations, the pure CP violation effect in ⌬ P( → ) is very small (ϳ0.01) and is comparable to the matter effect. For → e oscillation, the pure CP violation effect is independent of the active-sterile admixture and is at most 0.05 in Eϭ1.5-3 GeV at L ϭ290 km and the matter effect is at the 15-30 % level.