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A. Ilyichev

Publications and source records attributed to A. Ilyichev.

At least 19 recordsLinked to original sources
arXiv2023

Complete lowest order radiative corrections in semi-inclusive scattering of polarized particles

The lowest order radiative corrections to the cross section and asymmetries measured in experiments on semi-inclusive deep inelastic scattering of polarized particles were calculated. Both exact and leading log expressions were presented and discussed for the total correction that include the contributions from the processes of (i) real photon emission with semi-inclusive processes, (ii) loop diagrams, and (iii) real photon emission with exclusive processes. Radiative corrections to the Sivers and Collins asymmetries in $π^+$ electroproduction were studied numerically within the kinematical conditions of modern experimental environments at Jefferson Laboratory (JLab). The Wandzura-Wilczek approximation for the semi-inclusive structure functions and MAID2007 parameterization for the six amplitudes of exclusive processes were used in numeric analyses. The results show that (i) radiative effects can generate a correction comparable to the size of Sivers and Collins asymmetries at the Born level, (ii) there is good agreement between the exact and leading-order corrections, (iii) external functions (that is, other than the Sivers and Collins functions in the respective asymmetries) can generate a contribution to the radiative correction up to 20\%, and (iv) there exists a strong dependence of the radiative correction on the models for semi-inclusive and exclusive structure functions.

hep-ph↗
arXiv2022

ESFRAD. FORTRAN code for calculation of QED corrections to polarized ep-scattering by the electron structure function method

The main features of the electron structure function method for calculations of the higher order QED radiative effects to polarized deep-inelastic ep-scattering are presented. A new FORTRAN code ESFRAD based on this method was developed. A detailed quantitative comparison between the results of ESFRAD and other methods implemented in the codes POLRAD and RADGEN for calculation of the higher order radiative corrections is performed.

hep-ph↗
arXiv2022

Charge-asymmetric correlations in elastic lepton- and antilepton-proton scattering from real photon emission

Observation of charge asymmetry by comparing electron and positron, or muon and anti-muon, scattering on a hadronic target presently serves as an experimental tool to study two-photon exchange effects. In addition to two-photon exchange, real photon emission also contributes to the charge asymmetry. We present a theoretical formalism, explicit expressions, and a numerical analysis of hard photon emission for the charge asymmetry in lepton- and antilepton-proton scattering. Different kinematic conditions are considered, namely, either fixed transferred momentum squared or a fixed lepton scattering angle. The infrared divergence from real photon emission is treated by the Bardin-Shumeiko technique and canceled with the soft part of the two-photon exchange contribution extracted and calculated using Tsai approach. All final expressions are obtained beyond the ultrarelativistic approximation with respect to the lepton mass that allows to evaluate numerically of the considered effects not only for ultrarelativistic leptons (JLab) and but for moderately relativistic (MUSE) kinematics, too.

hep-ph↗
arXiv2021

Radiative corrections to the lepton current in unpolarized elastic $lp$-interaction for fixed $Q^2$ and scattering angle

The kinematical difference between the description of radiative effects for fixed $Q^2$ vs a fixed scattering angle in the elastic lepton-proton ($lp$)-scattering is discussed. The technique of calculation as well as explicit expressions for radiative corrections to the lepton current in unpolarized elastic $lp$-scattering for these two cases are presented without using an ultrarelativistic approximation. A comparative numerical analysis within kinematic conditions of Jefferson Lab measurements and MUSE experiment in PSI is performed.

hep-ph↗
arXiv2021

An experimental program with high duty-cycle polarized and unpolarized positron beams at Jefferson Lab

Positron beams, both polarized and unpolarized, are identified as essential ingredients for the experimental programs at the next generation of lepton accelerators. In the context of the hadronic physics program at Jefferson Lab (JLab), positron beams are complementary, even essential, tools for a precise understanding of the electromagnetic structure of nucleons and nuclei, in both the elastic and deep-inelastic regimes. For instance, elastic scattering of polarized and unpolarized electrons and positrons from the nucleon enables a model independent determination of its electromagnetic form factors. Also, the deeply-virtual scattering of polarized and unpolarized electrons and positrons allows unambiguous separation of the different contributions to the cross section of the lepto-production of photons and of lepton-pairs, enabling an accurate determination of the nucleons and nuclei generalized parton distributions, and providing an access to the gravitational form factors. Furthermore, positron beams offer the possibility of alternative tests of the Standard Model of particle physics through the search of a dark photon, the precise measurement of electroweak couplings, and the investigation of charged lepton flavor violation. This document discusses the perspectives of an experimental program with high duty-cycle positron beams at JLab.

nucl-ex↗
arXiv2021

Contribution of hard photon emission to charge asymmetry in elastic (anti)lepton-proton scattering

The influence of the hard photon emission on the charge asymmetry in the (anti)lepton-proton elastic scattering was evaluated for the first time beyond the ultrarelativistic limit, while retaining the lepton mass at all steps of the calculation. This contribution - responsible for the charge asymmetry - is induced by interference between real photon emission from the lepton and proton. During the calculation any excited states of the intermediated proton are not considered, allowing us to use the standard fermionic propagator for this particle. The infrared divergence extracted using Lorenz-invariant approach of Bardin-Shumeiko is canceled by the corresponding soft part of the two-photon exchange contribution. Numerical analysis was performed within kinematic conditions of Jefferson Lab measurements and MUSE experiment in PSI.

hep-ph↗
arXiv2011

One-loop electroweak corrections for polarized Moller scattering at different renormalization schemes and conditions

Using two different approaches, we perform updated and detailed calculations of the complete one-loop (Next-to-Leading Order (NLO)) set of electroweak radiative corrections to the parity violating e- e- -> e- e- (gamma) scattering asymmetry. Our first approach, more classical, relies on calculations "by hand" with reasonable approximations. Our second approach relies on program packages FeynArts, FormCalc, LoopTools, and FORM. The detailed numerical analysis of the various contributions is provided for a wide range of energies relevant for the ultra-precise 11 GeV MOLLER experiment planned at the Jefferson Laboratory, as well as future experiments at the International Linear Collider (ILC). The numerical results obtained within the on-shell renormalization scheme using two different sets of renormalization conditions are in excellent agreement. We also calculate the total NLO correction in the Constrained Differential Renormalization (CDR) scheme. Analysis of the results, along with the increasing experimental precision, shows that it is feasible that the corrections at the Next-to-Next-to-Leading Order (NNLO) level may be important for the next generation of high-precision experiments.

hep-ph↗
arXiv2011

Monte Carlo generator ELRADGEN 2.0 for simulation of radiative events in elastic ep-scattering of polarized particles

The structure and algorithms of the Monte-Carlo generator ELRADGEN 2.0 designed to simulate radiative events in polarized ep-scattering are presented. The full set of analytical expressions for the QED radiative corrections is presented and discussed in detail. Algorithmic improvements implemented to provide faster simulation of hard real photon events are described. Numerical tests show high quality of generation of photonic variables and radiatively corrected cross section. The comparison of the elastic radiative tail simulated within the kinematical conditions of the BLAST experiment at MIT BATES shows a good agreement with experimental data.

hep-ph↗
arXiv2009

ELRADGEN 2.0: Monte Carlo generator for simulation of radiative events in polarized elastic electron-proton scattering

A new version of Monte Carlo generator ELRADGEN for simulation of real photon emission in elastic electron-proton scattering is presented. The extensions in the new version include opportunity to deal with polarized particles: longitudinally polarized electron and arbitrary polarized proton. Simulation strategy, specifications of used kinematics, structure of the contributions to the observed cross section, cross-checks, and numerical results for BLAST experimental setup are presented and briefly discussed.

hep-ph↗
arXiv2009

Lowest order QED radiative corrections to five-fold differential cross section of hadron leptoproduction

The contribution of exclusive radiative tail to the cross section of semi-inclusive hadron leptoproduction has been calculated exactly for the first time. Although the experience of inclusive data analyses suggests us that the contribution of radiative tail from the elastic peak is of particular importance, similar effects in the semi-inclusive process were only recently estimated in the peaking approximation. The explicit expressions for the lepton part of the lowest order QED contribution of exclusive radiative tail to the five-fold differential cross section are obtained and discussed. Numerical estimates, provided within Jefferson Lab kinematic conditions, demonstrate rather large effects of the exclusive radiative tail in the region at semi-inclusive threshold and for high energy of detected hadron.

hep-ph↗
arXiv2007

Moving medium electrodynamics approach for description of the electric and magnetic static polarizable properties of the nucleon at low energy

Using the relativistic electrodynamics of continuous media formalism and main relativistic quantum field theory principles the covariant Lagrangian of electromagnetic field interaction with polarizable 1/2-spin particles have been obtained. This Lagrangian let us to determine canonical and metric energy-momentum tensors as well as low-energy Compton scattering amplitude. The application of this Lagrangian for the calculation of the radiative correction to the imaginary part of double virtual Compton scattering is demonstrated.

hep-ph↗
arXiv2006

Static polarizability vertex and its applications

Using the Lagrangian that was developed on the corresponding principle between the moving medium electrodynamic and quantum field theory the explicit expression for the static polarizability vertex has been obtained. The applications of this vertex for calculations of real Compton scattering amplitude as well as the imaginary part of doubly virtual Compton scattering amplitude have been demonstrated.

hep-ph↗
arXiv2005

Lowest order QED radiative corrections to longitudinally polarized Moller scattering

The total lowest-order electromagnetic radiative corrections to the observables in Moller scattering of longitudinally polarized electrons have been calculated. The final expressions obtained by the covariant method for the infrared divergency cancellation are free from any unphysical cut-off parameters. Since the calculation is carried out within the ultrarelativistic approximation our result has a compact form that is convenient for computing. Basing on these expressions the FORTRAN code MERA has been developed. Using this code the detailed numerical analysis performed under SLAC (E-158) and JLab kinematic conditions has shown that the radiative corrections are significant and rather sensitive to the value of the missing mass (inelasticity) cuts.

hep-ph↗
arXiv2003

Electroweak radiative effects in the single $W$-production at Tevatron and LHC

An alternative calculation of the lowest order electroweak radiative corrections to the single W-boson production in hadron-hadron collision in the framework of the quark parton model without any absorption of the collinear quark singularity into the parton distributions is carried out. Numerical analysis under Tevatron and LHC kinematic conditions is performed.

hep-ph↗
arXiv2001

Radiative effects in scattering of polarized leptons by polarized nucleons and light nuclei

Recent developments in the field of radiative effects in polarized lepton-nuclear scattering are reviewed. The processes of inclusive, semi-inclusive, diffractive and elastic scattering are considered. The explicit formulae obtained within the covariant approach are discussed. FORTRAN codes POLRAD, RADGEN, HAPRAD, DIFFRAD and MASCARAD created on the basis of the formulae are briefly described. Applications for data analysis of the current experiments on lepton-nuclear scattering at CERN, DESY, SLAC and TJNAF are illustrated by numerical results.

hep-ph↗