[en] The cross section of electron and positron annihilation at high energy equalling 5 photons is calculated using the method of spiral amplitudes. Kinematics corresponding to the events when in the beam inertia center system the angles between photon pulses and beam axes are not small, is considered. Validation of total cross section of multiphoton annihilation of a pair at high energies are presented. Annihilation channels of orthopositronium with 3 and 5 photons are considered. Exact expression for spiral amplitudes is presented

[en] The technique of helicity amplitudes is used to calculate the cross sections for the processes e⁺e^-→μ⁺μ^-γγ and e⁺e^-→e⁺e^-γγ in the limit of high energies under the condition that the angles between the 3-momenta of all the pairs of particles in the c.m.s. are not small

[en] Cross sections of the e⁺e^-→μ⁺μ^-γγ and e⁺e^-→e⁺e^-γγ processes are calculated in the high energy limit under the condition that angles between 3-momenta in c.m.s. are not small for every particle pair. The method of helicity amplitudes has been used

[en] The results of a search for the top quark taken from 15pb^-1 of data accumulated by the DOe experiment at the Tevatron are presented. No conclusive evidence for top is found. An upper limit on value of the tt cross section is measured to be 12.6pb with 95% CL. The lower limit to the top mass established above 131GeV assuming standard model decays. ((orig.))

[en] A system of two-coordinate cylindrical proportional chambers is developed for experiments on studying the e⁺e^- annihilation. The system consists of 6 independent proportional chambers of semicylindrical configuration with a gap between anode and cathode equal to 5 mm. The diameter of an external chnsamber equals 25 cm and its length cotitutes 40 cm. Anode wires 20 μm in-diameter are fixed in parallel to the system axis with a pitch of 2-3 mm. The use of a resisti ve cothode permitting to maintain the anode wires and delay circuits under the ground potential is one of the specific feabures of the given chamber. The resistive layer is produced by sputtering the aquadag aqueous suspension with the polyvinylacetate emulsion on a fibregrass-textolite. 8 delay circuits is mounted outside of each chamber from the side of the cathode. A functional flowsheet of a data readout system is given. The track angte is determined directiy according to the numbers of operated wires; coordinates along the axis are determined by means of the delay circuits placed outside the chamber near the resistive cathode. The accuracy of the coordinate measurement in both directions constitutes about 1 mm. Each chamber permits to measure the coordinates of several particles, if they entry into different delay circuits. The proportional chambers are filled with the mixture of Ar+30%CO². Anode and cathode efficiencies in the plateau region (150-250) exceed 99%

[en] Cross section of electron-positron annihilation into five photons at high energy is calculated using the helicity amplitude method. Above process is also of a special interest as higher-order perturbations of QED

[en] In the experiment with the Neutral Detector at the electron-positron collider VEPP-2M, the φ→π⁺π^- branching ratio B(φ→π⁺π^-)=[(0.63+0.37)-(063-0.28)]x10^-4 and the phase of interference with nonresonance amplitude ψ=(-20±13) deg have been measured by observed interference behaviour of the e⁺e^-→π⁺π^- cross section in the φ-meson range

[en] The design and characteristics of the neural detector based on NaI(Tl) crystals with a total weight of 2.6 t for experiments at the electron-positron storage ring VEPP-2M are described. The solid angle of the detector is 65% of 4 π sr. The energy resolution for photons in the energy range 50-1000 MeV is from 20% to 10% (fwhm). For events with the detection of all final particles a further improvement of the detector resolution by means of the kinematic reconstruction method is possible. For the decay phi -> etaγ -> 3γ an effective mass resolution of 10% is obtained for the eta-meson mass. By the energy deposition in NaI(Tl) layers an electron/pion separation of 0.001 is achieved at an energy of 500 MeV. (orig.)

[en] The cross section for electron-positron annihilation into five photons at high energies is calculated using the method of helicity amplitudes. For var-phi-meson factories with luminosity L ∼10³³ cm^-2 s^-1 and large-angle photon detection with a threshold ω_min/E > 0.1, the number of such events can be as large as several tens per day. These events must be considered as background in studying the process e^-e⁺ → π⁰π⁰γ. Explicit expressions for the helicity amplitudes are presented. The above process is also interesting as a higher-order QED transition. 6 refs

[en] The complete results of the experiments carried out with the Neutral Detector at the e⁺e^- storage ring VEPP-2M in the energy range 2E=0.5-1.4 GeV are reviewed. The data sample corresponds to a total integrated luminosity of 19 pb^-1. (orig.) With 163 refs