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We study the CP-violating asymmetry A CP , which arises, in η → π + π − e + e − , from the angular correlation of the e + e − and π + π − planes due to the interference between the magnetic and electric decay amplitudes. With the phenomenologically determined magnetic amplitude and branching ratio as input, the asymmetry, induced by the electric bremsstrahlung amplitude through the CP-violating decay η → π + π − , and by an unconventional tensor type operator, has been estimated respectively. The upper bound of A CP from the former is about 10 −3 , and the asymmetry from the latter might be up to O(10 −2 ). One can therefore expect that this CP asymmetry would be an interesting CP-violating observable for the future precise measurements in the η factories. †

The radiative Higgs decays h → γl + l − with l = e, µ and τ are analyzed in the standard model using m h = 125 GeV. Both tree and one-loop diagrams for the processes are evaluated. In addition to their decay rates and dilepton invariant mass distributions, we focus on the forward-back asymmetries in these modes. Our calculation shows that the forward-backward asymmetries in h → γe + e − and h → γµ + µ − could be up to 10 −2 while in the τ + τ − final state, these asymmetries are below 1%. Thus the forward-backward asymmetries in h → γl + l − might be interesting observables in the future precise experiments both to test our understanding of Higgs physics in the standard model and to probe the novel Higgs dynamics in new physics scenarios. *

Based on experimental data by Bell Collaboration, we present a phenomenological analysis of the angular distributions in τ − → K S π − ν τ decay. Our study shows that the angular analysis could lead to some interesting observables, and the future experimental investigation of these observables might be very helpful to reveal the nature of the scalar components of the decay. New physics contributions from two-Higgs-doublet model to this decay have also been examined. †