[en] Charmed meson decays to a light pseudoscalar (P) and light vector (V) meson are analyzed taking account of η-η^' mixing. A frequently-used octet-singlet mixing angle of 19.5 degree sign is compared with a value of 11.7 degree sign favored by a recent analysis of D→PP decays.

[en] In a covariant level-classification scheme of hadrons proposed recently, the existence of ''chiral particles'', scalar and axial-vector mesons as the partners of the ground-state pseudo-scalar and vector mesons, respectively, were predicted in D and B meson systems, realizing a linear representation of chiral symmetry concerning the light quarks. In this work we reanalyze the D*π mass spectra obtained through Υ(4S) and Z⁰ decay and the Bπ spectra obtained through Z⁰ decay to show the possibility of the existence of D₁^χ and B₀^χ, respectively. This talk is a review of essential points of our previous work. (author)

[en] Low mass meson states observed experimentally are reviewed briefly. Most of them seem difficult to be accommodated in the conventional SU(3) qq-bar nonet. (author)

[en] It is supposed that families of vector mesons ρ, ψ, Υ contain an infinite number of resonances with gradually increasing widths. The asymptotic freedom requirement involves a relationship between the electronic width of a resonance and its mass derivative over the number. Using of this relationship it is shown that for the families of ψ and Υ mesons the moment from experimental function R(s)is egual to the sum of the moment from a bare quark loop and the edge term which arised from replacing of summation by integration. These equalities are fulfilled up to 1% for 60 moments in the ψ-meson family and up to 2% for 96 moments in the Υ-meson family. The electronic widths of the considered resonances and the ρ-meson mass are calculated

[en] Some recent experimental observations made on the meson spectrum are discussed, with particular attention to qq-bar radial excitations and to possible non-qq-bar states. This review is mainly based on analyses of proton-antiproton annihilations at low energy. For a more complete review, see the 1998 edition of the Review of Particle Physics

[en] One never quite knows what to say in a summary. If you were at the sessions, you heard the same talks I did. Perhaps the purpose is to summarize the parallel sessions, but like you, I can only attend one of these sessions. In addition, the time is short, so that this cannot be a real summary. What I will present are impressions of the past two days, and these will certainly be colored by my own views. Thus at the outset, let me apologize for any and all omissions and distortions. I will cover primarily the plenary session talks, but will organize this summary along the following lines: 1. vector (V) mesons; 2. pseudoscalar mesons, and 3. other subjects, notably with electrons. This afternoon's talks are so close in time to this summary that I shall omit them. (author)

[en] A series of new scalar and tensor mesons has been discovered at LEAR, mostly in the Crystal Barrel experiment. One of these states, the f₀(1500), has unusual properties: a comparatively narrow width and a decay pattern which seems incompatible with SU(3) relations based on the OZI rule. In a naive quark model a s anti(s) state should be expected at this mass but the f₀(1500) partial decay width to anti(K)K is small. This leads to the conclusion that the state is supernumerous and must interpreted as the ground-state scalar glueball mixing with nearby quarkonia. Alternative interpretations are however not yet ruled out. (author)

[en] The work is aimed at discussing lower multiplets of radial excited states of light vector and pseudoscalar mesons. The authors follow an earlier developed scheme of phenomenologic analysis of radial excitations of qq-bar-systems (with orbital moment L=0). The conclusion is made that an adequate interpretation of pseudoscalar resonances largerly depends on solution of a number of problems connected with the general establishment of mass spectrum and other properties of radial excitations of light mesons. Presently known J^PC=0^± isosinglet (I⁶=O⁺) resonances are presented. A share of decay of J/ψ meson to form the assigned meson; the ratio of cross sections of production of the given meson and η-meson in π^-p reaction; width of two-photon decay of the given meson are presented. No significant mixing of pseudoscalar glueball with radial excitations of qq-states is supposed. The comparison of results obtained with the experiment will permit to estimate the degree of necessity of including new (gluon or multiquark) degrees of freedom to describe the picture observed

[en] The hypothesis that there exists a nonet of scalars mainly composed of a valence quark-antiquark pair and mixed according to near singlet-octet separation: f₀(980) singlet, a₀^+,0,- (980) , K₀*^+,0(1430), K-bar₀*^-,0 (1430) f₀(1500) octet, is put to further tests from the three body decays D^±, D_s^± → PS^± = π⁺, ^- with PS^± π^± , K^±. The analysis of decay phases supports the singlet nature of f₀(980)

[en] We first review the work of the Syracuse group, which uses an effective chiral Lagrangian approach, on meson-meson scattering. An illustration providing evidence for the existence of a strange scalar resonance of mass around 900 MeV is given. An attempt to fit this κ(900) together with a similarly obtained σ(560) and the well known a₀(980) and f₀(980) into a nonet pattern suggests that the underlying structure is closer to a dual quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain a next higher-in mass scalar meson nonet is also discussed. This involves mixing between qq-bar and qqq-barq-bar states. (author)