[en] The authors evaluate the combined sensitivity of the four LEP collaborations to exclude or discover the Standard Model Higgs boson with the LEP collider at centre-of-mass energies of 189-200 GeV. It is argued that neighter Standard Model nor the Supersymmetric Higgs search benefits from an upgrade of LEP to its peak centre-of-mass energy (e.g. upgrade 198 GeV to 200 GeV) if this degrades the integrated luminosity by a factor of two or more. 7 refs., 11 figs

[en] A search has been made for weakly interacting light neutral particles in a beam-dump experiment at the 70-GeV accelerator of the Institute of High Energy Physics, Serpukhov. Analysis of high-energy electromagnetic showers from the possible decays H → e⁺e^- and H → γγ in the neutrino detector of the IHEP and the Joint Institute for Nuclear Research reveals no signal above the background. Limits are found on the mass of the light Higgs boson within the framework of the standard model on the basis of theoretical branching ratios for the production of light Higgs bosons in the decays π^± → e^± v_eH, K^± → e^± v_eH, K^± → π^±H, K_L⁰ → π⁰H, and η' → ηH. 23 refs., 3 figs., 1 tab

[en] We study the forbidden in vacuum decay of pseudoscalar particle into charged fermion-antifermion pair α → f f-tilde induced by external magnetic field. As an example of the pseudoscalar particle we consider the widely discussed axion. Contributions of the lowest and the highest Landau levels to the decay probability are discussed. The results obtained demonstrate the catalyzing influence of the external field

[en] The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to study semiclassical production of pions in the central region. The mechanism is related to the isospin-uniform solution of the nonlinear σ-model coupled to quark degrees of freedom. The multipion exchange potential between two quarks is derived. It is shown that the soft chiral pion Bremsstrahlung also leads to anomalously large fluctuations in the ratio of neutral to charged pion.. We show that only direct production of pions in the form of an isoscalar coherent pulse without isovector pairs can lead to large neutral-charged fluctuations. (Authors)

[en] A simple experiment establishing the property of mechanical momentum of photon is described. An attempt has also been made to give a quantitative formulation. (author). 4 refs., 2 figs

[en] A possible measurement of the top quark mass by an energy scan of the t anti t threshold region at e⁺e^- colliders of √s = 250--500 GeV is discussed. With an integrated luminosity of 1 fb^-1 devoted to the energy scan, a top quark mass of about 150 GeV can be determined with an accuracy of ∼ 0.3 GeV, with a comparable systematic uncertainty arising from the few % errors in the α_s measurement at LEP-I. The possibilities of studying Γ_t and Higgs boson effects are also discussed

[en] By surrounding an Abelian Dyon with an axion-like domain wall the screening effects generated by the domain wall on the dyon degrees of freedom is calculated. (author). 21 refs

[en] We examine the collapse of an axionic domain wall bounded by an axionic string. It is found that the collapse proceeds quickly and axionic domain walls disappear. However axions are emitted in the collapse and its energy density increases during the radiation-dominated era and contributes significantly to the present mass density of the Universe. In particular the axion emitted from the wall can account for the dark matter in the Universe for F_a approx-gt 10¹⁰ GeV

[en] We calculate the flux of cosmic γ rays expected from the annihilation of neutralinos in the galactic halo. Our calculation of the annihilation cross section to two photons improves the existing calculations by inclusion of exact one-loop diagrams for the amplitudes involving Higgs boson and chargino states as well as those involving fermion and sfermion states. A survey of supersymmetric parameter space shows that numerous models would be observable at the 3σ level with an air Cherenkov telescope with an exposure of 10⁴ m² yr

[en] We investigate production process of the scalar partner of top-quark (stop) at TRISTAN energies in the framework of the minimal supersymmetric standard model (MSSM). The existence of the light stop, which is lighter than the top-quark as well as the other squarks, is natural consequence of the MSSM and the stop with mass ∼ 30 GeV has not been excluded both in TEVATRON and LEP data. It is shown that TRISTAN has wider parameter region of the stop than TEVATRON and LEP, if we take careful analyses of the experimental signature cc-bar plus missing energies. Comments on the stoponium production at two photon process at TRISTAN and on the stoponium interpretation of the L3 and DELPHI events are also given. (author)