A. I. Ahmadov

Radiative corrections for electron proton elastic scattering taking into account high orders and hard photon emission

We investigate the effect of high order radiative corrections in unpolarized electron proton elastic scattering and compare with the calculations at lowest order, which are usually applied to experimental data. Particular attention is devoted to the

About the creation of proton–antiproton pair at electron–positron collider in the energy range of ψ(3770) mass

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TWO-PION PRODUCTION IN ELECTRON-POLARIZED PROTON SCATTERING

dependence of radiative corrections, which is directly related to the electric proton form factor. We consider in particular the effects of the interference terms for soft and hard photon emission. Both quadratic amplitude describing the collinear emission along the scattered electron as well as the interference with the amplitudes of emission from the initial electron and the emission from protons are important in leading and next to leading approximation and they may compensate in particular kinematical conditions.

Cross section of the processes e++e−→e++e−(γ), π++π−(γ), μ++μ−(γ), γ+γ(γ) in the energy region 200 MeV⩽2E⩽3 GeV

The process of electron positron annihilation into proton-antiproton pair is considered within the vicinity of psi(3770) resonance. The interference between the pure electromagnetic intermediate state and the psi(3770) state is evaluated. It is shown that this interference is destructive and the relative phase between these two contributions is large (phi(0) approximate to 250 degrees)

Cross section of the processes e+ + e- ---> e+ + e-(gamma), ---> pi+ + pi-(gamma), mu+ + mu-(gamma), gamma + gamma(gamma) in the energy region 200-MeV <= 2E <= 3-GeV

The process of two-pion production in the electron-polarized proton scattering is investigated. In the Weizsacker–Williams approximation the differential spectral distributions and the spin-momentum correlations are considered. The spin correlation effects caused by ρ-meson widths are estimated to be of an order of several per cent. Both channels of the π+π- and π+π0 creation are considered. The effects of intermediate excited baryons are not considered. The spectral distributions on pion energy fractions in polarized and unpolarized cases are presented analytically and numerically.

Alternative way of describing hadronic processes within the parton model

The cross section for different processes induced by e + e − annihilation, in the kinematical limit β μ ≈ β π = ( 1 − m π 2 / ϵ 2 ) 1 / 2 ∼ 1 , is calculated taking into account first order corrections to the amplitudes and the corrections due to soft emitted photons, with energy ω ⩽ Δ E ⩽ ϵ in the center of mass of the e + e − colliding beams. The results are given separately for charge-odd and charge-even terms in the final channels π + π − ( γ ) and μ + μ − ( γ ) . In case of pions, form factors are taken into account. The differential cross sections for the processes: e + + e − → e + + e − ( + γ ) , → π + + π − ( γ ) , → μ + + μ − ( γ ) , → γ + γ ( γ ) have been calculated and the corresponding formulas are given in the ultrarelativistic limit s / 2 = ϵ ≫ m μ ∼ m π . For a quantitative evaluation of the contribution of higher order of the perturbation theory, the production of π + π − , including radiative corrections, is calculated in the approach of the lepton structure functions. This allows to estimate the precision of the obtained results as better than 0.5% outside the energy region corresponding to narrow resonances. A method to integrate the cross section, avoiding the difficulties which arise from singularities is also described.

Three jet production in peripheral antiproton (proton) - proton collisions

The cross section for different processes induced by e + e − annihilation, in the kinematical limit β μ ≈ β π = ( 1 − m π 2 / ϵ 2 ) 1 / 2 ∼ 1 , is calculated taking into account first order corrections to the amplitudes and the corrections due to soft emitted photons, with energy ω ⩽ Δ E ⩽ ϵ in the center of mass of the e + e − colliding beams. The results are given separately for charge-odd and charge-even terms in the final channels π + π − ( γ ) and μ + μ − ( γ ) . In case of pions, form factors are taken into account. The differential cross sections for the processes: e + + e − → e + + e − ( + γ ) , → π + + π − ( γ ) , → μ + + μ − ( γ ) , → γ + γ ( γ ) have been calculated and the corresponding formulas are given in the ultrarelativistic limit s / 2 = ϵ ≫ m μ ∼ m π . For a quantitative evaluation of the contribution of higher order of the perturbation theory, the production of π + π − , including radiative corrections, is calculated in the approach of the lepton structure functions. This allows to estimate the precision of the obtained results as better than 0.5% outside the energy region corresponding to narrow resonances. A method to integrate the cross section, avoiding the difficulties which arise from singularities is also described.