arXiv subjects

V. V. Bytev

Publications and source records attributed to V. V. Bytev.

32 records · Page 2Linked to original sources

arXiv2007

Sum rule for the double virtual Compton scattering

The two photon exchange amplitude is investigated in frame of analytic properties of the virtual Compton scattering amplitude as a function of the invariant mass squared of the intermediate hadronic state. A sum rule is built, based on arguments from analyticity. It relates the differential cross section of elastic electron-proton scattering including form factors, and the cross section of inelastic scattering channel, with a contribution of nucleon anti-nucleon pair production arising from the Fermi statistics. The last term is calculated in frame of a simple model of nucleon-pion interaction.

hep-ph↗

arXiv2007

Charge asymmetry for electron (positron)-proton elastic scattering at large angle

Charge asymmetry in electron (positron) scattering arises from the interference of the Born amplitude and the box-type amplitude corresponding to two virtual photons exchange. It can be extracted from electron proton and positron proton scattering experiments, in the same kinematical conditions. Considering the virtual photon Compton scattering tensor, which contributes to the box-type amplitude, we separate proton and inelastic contributions in the intermediate state and parametrize the proton form-factors as the sum of a pure QED term and a strong interaction term. Arguments based on analyticity are given in favor of cancellation of contributions from proton strong interaction form factors and of inelastic intermediate states in the box type amplitudes. In frame of this model, with a realistic expression for nucleon form-factors, numerical estimations are given for moderately high energies.

hep-ph↗

arXiv2007

Radiative corrections to DVCS electron tensor

Radiative corrections in leading logarithmic approximation are calculated for the differential cross section of $e^- μ^+$ radiative scattering. In particular the interference term due to photon emission from electron and muon blocks are calculated in helicity independent and dependent parts. The calculation is applied to the kinematical conditions of existing DVCS data in electron-proton collisions. Both helicity odd and helicity even differential cross sections are considered.

hep-ph↗

arXiv2007

Comments to the calculation of transverse beam spin asymmetry for electron proton elastic scattering

The transverse beam spin induced asymmetry is calculated for the scattering of transversally polarized electrons on a proton target within a realistic model. Such asymmetry is due to the interference between the Born amplitude and the imaginary part of two photon exchange amplitude. In particular, the contribution of non-excited hadron state (elastic) to the two photon amplitude is calculated. The elastic contribution requires infrared divergences regularization and can be expressed in terms of numerical integrals of the target form factor. The inelastic channel corresponding to the one pion hadronic state contribution is enhanced by squared logarithmic terms. We show that the ratio of elastic over inelastic channel is of the order of 0.3 and cannot be ignored. Enhancement effects due to the decreasing of form factors bring the transverse beam asymmetry to values as large as $10^{-4}$ for particular kinematical conditions.

hep-ph↗

arXiv2006

Charge asymmetry for electron (positron)-proton elastic scattering

Charge asymmetry in electron (positron) scattering arises from the interference of the Born amplitude and the box-type amplitude corresponding to two virtual photons exchange. It can be extracted from electron proton and positron proton scattering experiments, in the same kinematical conditions. Considering the virtual photon Compton scattering tensor, which contributes to the box-type amplitude, we separate proton and inelastic contributions in the intermediate state and parametrize the proton form-factors as the sum of a pure QED term and a strong interaction term. Arguments, based on analyticity, are given in favor of cancellation of contributions from proton strong interaction form factors and of inelastic intermediate states in the box type amplitudes. In frame of this model, and assuming a dipole character of form-factors, numerical estimations are given for moderately high energies.

hep-ph↗

arXiv2006

Target normal spin asymmetry and charge asymmetry for $eμ$ elastic scattering and the crossed processes

Two kinds of asymmetry arise from the interference of the Born amplitude and the box-type amplitude corresponding to two virtual photons exchange, namely charge-odd and one spin asymmetries. In case of unpolarized particles the charge-odd correlation is calculated. It can be measured in combination of electron muon and positron muon scattering experiments. The forward-backward asymmetry is the corresponding quantity which can be measured for the crossed processes. In the case of polarized muon the one-spin asymmetry for annihilation and scattering channels has been calculated. The additional structure function arising from the interference is shown to suffer from infrared divergencies. The background due to electroweak interaction is discussed.

hep-ph↗

arXiv2005

Quark loop contribution to π^0 \to 4γ

We find the contribution of constituent quark loop mechanism to the branching ratio B_{4γ} = Γ_{4γ}/Γ_{4γ} \sim 5.45 \cdot 10^{-16} for the reasonable choice of constituent quark mass m \sim 280 MeV. This result is in agreement with vector-dominance approach result obtained years ago. Thus the main contribution arises from QED mechanism π^0 \to γ(γ^*) \to γ(3γ) including light-light scattering block with electron loop. This contribution was investigated in paper of one of us and gave B_{4γ} \sim 2.6 \cdot 10^{-11}.

hep-ph↗

arXiv2004

Charge asymmetry in $π^+π^-$ electroproduction on proton at high energies as a test of $σ,ρ$ mesons degeneration

The charge asymmetry induced by interference of amplitudes with $σ$ and $ρ$ mesons decaying to $π^+π^-$ pair created in the fragmentation region of proton, suggest to be a test of degeneration hypothesis of $ρ$ and $σ$ mesons. Some numerical estimations are given.

hep-ph↗

arXiv2003

Radiative muon pair production in high energy electron-positron annihilation process

The lowest order radiative correction to the differential cross-section of process of muon pair production with emission of hard photon at high energy electron-positron annihilation are calculated. Taking into account the emission of additional soft and hard photon the cross-section can be put in the form of Drell-Yan process in leading logarithmical approximation. Applying the crossing transformation we obtain the cross section of radiative electron-muon high-energy scattering process. Virtual and soft photon emission contributions of non-leading form are tabulated for several typical kinematical points. The limit of small invariant mass of muon pair is in agreement with our previous analysis.

hep-ph↗

arXiv2003

Radiative muon (pion) pair production in high energy electron-positron annihilation (the case of small invariant pair mass)

The process of the muon (pion) pair production with small invariant mass in the electron--positron high--energy annihilation, accompanied by emission of hard photon at large angles, is considered. We find that the Drell--Yan picture for differential cross section is valid in the charge--even experimental set--up. Radiative corrections both for electron block and for final state block are taken into account.

hep-ph↗

arXiv2003

Radiative muon (pion) pair production in high energy electron-positron annihilation process

Process of muon (pion) pair production with small invariant mass in the electron-positron high-energy annihilation, accompanied by emission of hard photon at large angles, is considered. We find that the Dell-Yan picture for differential cross section is valid in the charge-even experimental set-up. Radiative corrections both for electron block and for final state block are taken into account.

hep-ph↗

arXiv2002

(Quasi)elastic electron-muon large-angle scattering to a two-loop approximation: eikonal type contributions I

Part of eikonal type contributions to $eμ$ large-angle high-energy scattering cross section is considered in a quasi-elastic experimental set-up. Apart from virtual corrections we examine inelastic processes with emission of one and two soft real photons as well as soft lepton and pion pairs. Virtual photon contributions are given within a logarithmic accuracy. Box type Feynman amplitudes with leptonic and hadronic vacuum polarization insertion are considered explicitly as well as double box ones. Wherever appropriate analytic expressions obtained are compared with those predicted by a structure function approach.

hep-ph↗

arXiv2002

Polarized triplet production by circularly polarized photons

A process of the pair production by a circularly polarized photon in the field of unpolarized atomic electron has been considered in the Weizaecker-Williams approximation. The degree of longitudinal polarization of positron and electron has been calculated. An exclusive cross-section as well as a spectral distribution are obtained. We estimate the accuracy of our calculations at the level of a few percent. We show the identity of the positron polarization for considered process and for process of pair production in the screened Coulomb field of nucleus.

hep-ph↗

arXiv2002

(Quasi)elastic electron--muon large-angle scattering to a two-loop approximation: vertex contributions

We consider a process of quasielastic $eμ$ large-angle scattering at high energies with radiative corrections up to a two-loop level. A lowest order radiative correction arising both from one-loop virtual photon emission and a real soft emission are presented to a power accuracy. Two-loop level corrections are supposed to be of three gauge-invariant classes. One of them, so called vertex contribution, is given in logarithmic approximation. Relation with the renormalization group approach is discussed.

hep-ph↗