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N. P. Merenkov

Publications and source records attributed to N. P. Merenkov.

At least 37 records · Page 2Linked to original sources
arXiv2005

Single--Spin Asymmetries in the Bethe--Heitler Process $e^- + p \to e^- + γ+ p$ from QED Radiative Corrections

We derived analytic formulae for the polarization single--spin asymmetries (SSA) in the Bethe--Heitler process $e^- + p \to e^- + γ+ p$. The asymmetries arise due to one-loop QED radiative corrections to the leptonic part of the interaction and present a systematic correction for the studies of virtual Compton Scattering on a proton through interference with the Bethe-Heitler amplitude. Considered are SSA with either longitudinally polarized electron beam or a polarized proton target. The computed effect appears to be small, not exceeding 0.1 per cent for kinematics of current virtual Compton scattering experiments.

hep-ph↗
arXiv2004

Vector meson dominance pion electromagnetic form factor with the sigma-model loop corrections

A model is developed for electromagnetic form factor of the pion. One-loop corrections are included in the linear sigma-model. The rho-meson contribution is added in an extended VMD model. The form factor, calculated without fitting parameters, is in a good agreement with experiment for space-like and time-like photon momenta. Loop corrections to the two-pion hadronic contribution a^{(had, π)}_μto the muon anomalous magnetic moment are calculated. The optimal value of the sigma-meson mass appears to be close to the rho-meson mass.

hep-ph↗
arXiv2004

Large Logarithms in the Beam Normal Spin Asymmetry of Elastic Electron--Proton Scattering

We study a parity-conserving single-spin beam asymmetry of elastic electron-proton scattering induced by an absorptive part of the two-photon exchange amplitude. It is demonstrated that excitation of inelastic hadronic intermediate states by the consecutive exchange of two photons leads to logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. The asymmetry at small electron scattering angles is expressed in terms of the total photoproduction cross section on the proton, and is predicted to reach the magnitude of 20-30 parts per million. At these conditions and fixed 4-momentum transfers, the asymmetry is rising logarithmically with increasing electron beam energy, following the high-energy diffractive behavior of total photoproduction cross section on the proton.

hep-ph↗
arXiv2002

Nucleon Compton Scattering with Two Space--Like Photons

We calculated two--photon exchange effects for elastic electron--proton scattering at high momentum transfers. The corresponding nucleon Compton amplitude is defined by two space--like virtual photons that appear to have significant virtualities. We make predictions for a) a single--spin beam asymmetry, and b) a single--spin target asymmetry or recoil proton polarization caused by an unpolarized electron beam.

hep-ph↗
arXiv2002

Scanning of the e+e- to pi+pi- cross--section below 1 GeV by radiative events with untagged photon

We discuss an inclusive approach to the measurement of the e+e- --> pi+ pi- cross--section by the radiative return method without photon tagging. The essential part of this approach is the choice of rules for event selection which provide rejection of events with 3 (or more) pions and decrease the final--state radiation background. The radiative corrections to the initial--state radiation process are computed for DAPhNE conditions, using the quasi--real electron approximation for both, the cross--section and the underlying kinematics. The two cases of restricted and unrestricted pion phase space are considered. Some numerical calculations illustrate our analytical results.

hep-ph↗
arXiv2001

QED correction to asymmetry for polarized ep-scattering from the method of the electron structure functions

The electron structure function method is applied to calculate model-independent radiative corrections to an asymmetry of electron-proton scattering. The representations for both spin-independent and spin-dependent parts of the cross-section are derived. Master formulae take into account the leading corrections in all orders and the main contribution of the second order next-to-leading ones and have accuracy at the level of one per mille. Numerical calculations illustrate our analytical results for both elastic and deep inelastic events.

hep-ph↗
arXiv2001

Radiative Corrections to Polarized Inelastic Scattering in Coincidence

The coplete analysis of the model-independent leading radiative corrections to cross-section and polarization observables in semi-inclusive deep-inelastic electron-nucleus scattering with detection of a proton and scattered electron in coincidence has been performed. The basis of the calculations consists of the Drell-Yan like representation in electrodynamics for both spin-independent and spin-dependent parts of the cross-section in terms of the electron structure functions. The applications to the polarization transfer effect from longitudinally polarized electron beam to detected proton as well as to scattering by the polarized target are considered.

hep-ph↗
arXiv2000

Radiative Correction to the Transferred Polarization in Elastic Electron-Proton Scattering

Model independent radiative correction to the recoil proton polarization for the elastic electron-proton scattering is calculated within method of electron structure functions. The explicit expressions for the recoil proton polarization are represented as a contraction of the electron structure and the hard part of the polarization dependent contribution into cross-section. The calculation of the hard part with first order radiative correction is performed. The obtained representation includes the leading radiative corrections in all orders of perturbation theory and the main part of the second order next-to-leading ones. Numerical calculations illustrate our analytical results.

hep-ph↗
arXiv2000

About the end of the electron spectrum in five-lepton $μ^+$ decay

The spectrum of very fast electrons in five-lepton decay $μ^+\to e^-e^+e^+ν\barν,$ that is the main background decay at the study of the muonium-antimuonium conversion in vacuum, is considered. The essential decrease of the spectral distribution is demonstrated when the energy of one positron in this decay is small. Some arguments for such decrease for arbitrary positron energies are given.

hep-ph↗
arXiv2000

Tagged-photon events in polarized DIS process

Deep-inelastic events for the scattering of the longitudinally polarized electron by polarized proton with tagged collinear photon radiated from initial-state electron are considered. The corresponding cross-section is derived in the Born approximation. The model-independent radiative corrections to the Born cross-section are also calculated. Obtained result is applied to the case of elastic scattering.

hep-ph↗
arXiv2000

Radiative Corrections to the Hadronic Cross-Section Measurement at DAPHNE

The hadronic invariant mass distribution for the process of electron-positron annihilation into a pair of charged pions accompanied by a photon radiated from the initial state has been studied for the region of DA$Φ$NE energies. The Born cross-section and the electromagnetic radiative corrections to it are calculated for realistic conditions of the KLOE detector. The dependence on the physical parameters which define the event selection is obtained.

hep-ph↗
arXiv1999

Current tensor with heavy photon for hard pair production by longitudinally polarized electron

The electron current tensor for the scattering of heavy photon on longitudinally polarized electron accompanied with additional hard electron-positron pair has been considered. The contribution of collinear and semicollinear kinematics is computed. The full analysis of both, spin-dependent and spin-independend parts of electron current tensor, is performed. The obtained result allows to calculate the corresponding contribution into the second order radiative correction to cross-sections of different processes with the next-to-leading accuracy.

hep-ph↗
arXiv1999

Hadronic Cross Sections in Electron-Positron Annihilation with Tagged Photon

Events with tagged photons in the process of electron-positron annihilation into hadrons are considered. The initial state radiation is suggested to scan the hadronic cross section with the energy. QED radiative corrections are taken into account. The results for the total and exclusive cross sections are given in an analytic form. Some numerical estimates are presented.

hep-ph↗
arXiv1999

Bhabha scattering at LEP1. Calorimeter event selection

Analitical calculations have been used to describe the calorimeter event selection in small-angle electron-positron scattering at LEP1. The first-order QED correction to the Born cross-section has been derived with leading log and the next-to-leading log approximations. The second- and the third-order corrections were computed with leading accuracy. The present analytical results are illustated by Tabeles and compared with the corresponding results obtained with the Monte Carlo generator BHLUMI.

hep-ph↗
arXiv1999

QED Corrections to Deep Inelastic Scattering with Tagged Photons at HERA

We calculate the QED corrections to deep inelastic scattering with tagged photons at HERA in the leading logarithmic approximation. Due to the special experimental setup, two large scales appear in the calculation that lead to two large logarithms of comparable size. The relation of our formalism to the conventional structure function formalism is outlined. We present some numerical results and compare with previous calculations.

hep-ph↗
arXiv1998

Current tensor with heavy photon for double hard photon emission by longitudinally polarized electron

The electron current tensor for the scattering of heavy photon on longitudinally polarized electron accompanied with two hard real photonsis considered. The contribution of collinear and semicollinear kinematics is computed. The obtained result allows to calculate the corresponding contribution into second order radiative correction to DIS or electron-positron annihilation cross-sections with the next-to-leading accuracy.

hep-ph↗