[en] Based on a 2 x 2 mass matrix, the mixing angle of the axial vector states f₁(1420) and f₁(1285) is determined to be 51.5 degree, and the theoretical results about the decay and production of the two states are presented. The theoretical results are in good agreement with the present experimental results, which suggests that f₁(1420) can be assigned as the partner of f₁(1285) in the ³P₁ q q-bar nonet. The authors also suggest that the existence of f₁(1510) needs further experimental confirmation

[en] Various phenomenological studies indicate that the mixing angle θ_K1 of K_1A and K_1B, the strange partners of the axial-vector mesons a₁(1260) and b₁(1235), respectively, lies in the vicinity of 35° or 55°, but whether this angle is larger or smaller than 45° still remains controversial. When the f₁(1285)-f₁(1420) mixing angle θ_³P1 and the h₁(1170)-h₁(1380) mixing angle θ_¹P1 are determined from the mass relations, they depend on the masses of K_1A and K_1B, which in turn depend on the mixing angle θ_K1. We show that the approximate decoupling of the light qq^¯ state from the heavier ss^¯ state, which is empirically valid for vector, tensor and 3^-- mesons, when applied to isoscalar axial-vector mesons, will enable us to discriminate different solutions of θ_³P1 and θ_¹P1 and pick up θ_K1∼35°. Indeed, for θ_K1∼55°, the predicted θ_¹P1 disagrees sharply with the recent lattice calculation and the implied large ss^¯ content of h₁(1170) and qq^¯ component of h₁(1380) cannot explain the observation of their strong decays. We conclude that θ_K1 is smaller than 45°.

[en] The mixing mechanism of three axial-vector meson f₁(1285), f₁(1530) and E/f₁(1420) is discussed. The results show that the main component of E/f₁(1420) is the glueball. On this basis we calculate the ratio of the helicity amplitudes and expect an experimental test for this result

[en] The K⁺K⁰π^- state has been produced by π^-, K^- and p beams at beam momenta of about 8 GeV/c. The π^- and p beam data show peaks at 1285 and 1420 MeV identified as the D(1285) and the E/ι(1420) The K^- beam data does not show any K⁺K⁰π^- peaks. A partial wave analysis of the π^- beam data show evidence of J^PC = 1⁺⁺ resonance at 1285 MeV together with a small 0^minus-plus peak. The 1420 MeV peak is mainly a 0^minus-plus resonance with a small amount of 1⁺⁺. There is an identification of a 1^± state at 1420 MeV. Also observed is a peak at a mass of 1512 MeV

[en] The diffractive production data for the 1⁺ ρπ state have been reanalysed with a simple parametrisation of the coherent background to a₁ resonance production. The results are in good agreement with more recent data from τ → a₁ν_τ and, within the assumptions made in the analysis, it is concluded that the mass of the a₁ is 1260±25 MeV and the width at that mass is 396±43 MeV. (orig.)

[en] A previous model where the low-lying axial-vector mesons are dynamically generated, implementing unitarity in coupled channels in the vector-pseudoscalar (VP) meson interaction, is applied to evaluate the decay widths of the a₁(1260) and b₁(1235) axial-vector mesons into πγ. Unlike the case of the a₁, the b₁ radiative decay is systematically underestimated at tree level. In this work we evaluate for the first time the loop contribution coming from an initial VP vertex. Despite the large superficial divergence of the loops, the convergence of the relevant loops can be established by using arguments of gauge invariance. The partial decay widths obtained agree with the experimental values within uncertainties, and we show that the loop contribution is crucial in the b₁ case and also important for the a₁ case

[en] We propose a less complex neural network that estimates and equalizes the nonlinear distortion of single frequency dual polarization data transmitted through a single mode optical fiber. We then analyze the influence of the size of the input data symbol window on the neural network design and the enhancement of the quality factor (Q-factor) that can be achieved by integrating the neural network with a perturbative nonlinearity compensation model. We significantly reduce the complexity of the neural network by determining the most significant inputs for the neural network from the self-phase modulation terms (intra-cross phase modulation and intra-four wave mixing) in the model. The weight matrices of the neural network are determined without prior knowledge of the system parameters while the complexity of the network is reduced in two stages through weight trimming technique and principle component analysis (PCA). Applying our procedure to a 3200 km double polarization 16-QAM optical system yields a ≈ 0.85 dB Q-factor enhancement with a 35% smaller number of inputs compared to previous designs.

[en] Current status of J_PC = 1^-+-exotic mesons is given. Recent analyses give strong support for the existence of the exotic mesons at masses 1.4 and 1.6 GeV, coupling to πη, πη', πρ and πb₁(1235)

[en] The first LEP result on the inclusive χ_c1 production in Z decays observed via the decay mode χ_c1 → J/ψ + γ, where J/ψ is reconstructed in its leptonic decay mode J/ψ → μ⁺μ^-. Assuming that there are no χ-c-0 and χ_c2 produced, the Branching ratio Br(Z → χ_c1 + X) has been determined and the branching ratio Br(b → J/ψ + X) has been updated. 2 figs., 12 refs

[en] I will summarize selected studies in bottomonium physics carried out by the BaBar experiment, including bottomonium decays to open charm, the study of χ_b1(1P) radiative decays, and the search for the η_b in hadronic transitions. (author)