If the fourth generation fermions exist, the new quarks could influence the branching ratios of the decays of B → X s γ and B → X s l + l − . We obtain two solutions of the fourth generation CKM factor V *We use these two solutions to calculate the new contributions of the fourth generation quark to Wilson coefficients of the decay of B → X s l + l − . The branching ratio and the forward-backward asymmetry of the decay of B → X s l + l − in the two cases are calculated. Our results are quite different from that of SM in one case, almost same in another case. If Nature chooses the formmer, the B meson decays could provide a possible test of the forth generation existence.

The inclusive process b→s␥ is studied in the littlest Higgs model. The contributions arising from new particles are normally suppressed by a factor of O(v 2 / f 2 ). Because of the large uncertainties of experimental measurements and theoretical predictions, the model parameters can escape from the constraints of present experiments provided f у1 TeV.

The disappearance of reactor νe observed by the Daya Bay experiment is examined in the framework of a model in which the neutrino is described by a wave packet with a relative intrinsic momentum dispersion σ rel . Three pairs of nuclear reactors and eight antineutrino detectors, each with good energy resolution, distributed among three experimental halls, supply a high-statistics sample of νe acquired at nine different baselines. This provides a unique platform to test the effects which arise from the wave packet treatment of neutrino oscillation. The modified survival probability formula was used to fit Daya Bay data, providing the first experimental limits: 2.38 • 10 −17 < σ rel < 0.23. Treating the dimensions of the reactor cores and detectors as constraints, the limits are improved: 10 −14 σ rel < 0.23, and an upper limit of σ rel < 0.20 is obtained. All limits correspond to a 95% C.L. Furthermore, the effect due to the wave packet nature of neutrino oscillation is found to be insignificant for reactor antineutrinos detected by the Daya Bay experiment thus ensuring an unbiased measurement of the oscillation parameters sin 2 2θ 13 and ∆m 2 32 within the plane wave model.

We investigate the ⑀Ј/⑀ for K→ in a sequential fourth generation model. By giving the basic formulas for ⑀Ј/⑀ in this model, we analyze the numerical results which are dependent on m t Ј and the imaginary part of the fourth CKM factor, ImV t Ј s * V t Ј d ͑or V t Ј s * V t Ј d and the fourth generation CKM matrix phase ). We find that, unlike the SM, when taking the central values of all parameters for ⑀Ј/⑀, the values of ⑀Ј/⑀ can easily fit to the current experimental data for all values of hadronic matrix elements estimated from various approaches. Also, we show that the experimental values of ⑀Ј/⑀ and rare K decays can provide a strong constraint on both mass and mixing of the fourth generation quark. When taking the values of hadronic matrix elements from the lattice or 1/N expansion calculations, a large region of the up-type quark mass m t Ј is excluded.