Covariant calculation of effective cross sections in quantum electrodynamics. II

1975 ◽  
Vol 18 (3) ◽  
pp. 363-366
Author(s):  
Yu. S. Perov
Keyword(s):  
Cross Sections ◽  
Quantum Electrodynamics ◽  
Covariant Calculation

scholarly journals Quantum electrodynamics with self-conjugated equations with spinor wave functions for fermion fields

2021 ◽  
pp. 2150086
Author(s):  
V. P. Neznamov ◽  
V. E. Shemarulin
Keyword(s):  
Cross Sections ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Quantum Electrodynamics ◽  
Lamb Shift ◽  
Wave Functions ◽  
Self Energy ◽  
Fermion Fields ◽  
Spinor Wave

Quantum electrodynamics (QED) with self-conjugated equations with spinor wave functions for fermion fields is considered. In the low order of the perturbation theory, matrix elements of some of QED physical processes are calculated. The final results coincide with cross-sections calculated in the standard QED. The self-energy of an electron and amplitudes of processes associated with determination of the anomalous magnetic moment of an electron and Lamb shift are calculated. These results agree with the results in the standard QED. Distinctive feature of the developed theory is the fact that only states with positive energies are present in the intermediate virtual states in the calculations of the electron self-energy, anomalous magnetic moment of an electron and Lamb shift. Besides, in equations, masses of particles and antiparticles have the opposite signs.

scholarly journals Fermion Scattering in a CPT-Even Lorentz Violation Quantum Electrodynamics

Symmetry ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 302 ◽  
Author(s):  
Frederico Santos ◽  
Manoel Ferreira
Keyword(s):  
Energy Dependence ◽  
Cross Sections ◽  
Quantum Electrodynamics ◽  
Lorentz Violation ◽  
Photon Propagator ◽  
Feynman Rules

In this work, we reassess two known processes of Quantum Electrodynamics involving electrons and muons. The photon propagator is modified by a CPT-even Lorentz-violating (LV) tensor, while fermion lines and the vertex interaction are not altered. Using the Feynman rules, the associated cross sections for unpolarized scatterings are evaluated, revealing the usual energy dependence and Lorentz-violating contributions that induce space anisotropy. A possible route to constraining the LV coefficients is presented and the results properly commented.

Relativistic elastic scattering of hydrogen atom by positron impact in a circularly polarized laser field

2013 ◽  
Vol 91 (9) ◽  
pp. 696-702 ◽  
Author(s):  
B. Manaut ◽  
S. Taj ◽  
M. El Idrissi
Keyword(s):  
New York ◽  
Elastic Scattering ◽  
Hydrogen Atom ◽  
Cross Sections ◽  
Differential Cross ◽  
Quantum Electrodynamics ◽  
Laser Field ◽  
Differential Cross Sections ◽  
Positron Impact ◽  
Circularly Polarized

In the framework of the first Born approximation and using the Dirac–Volkov formalism, we investigate the relativistic model describing the laser assisted elastic differential cross sections (DCSs) for positron scattering by the hydrogen atom. Both the DCSs for electron and positron are notably modified by the circularly polarized laser field, particularly in the regime of high energies and medium intensities. Comparing the two numerical DCSs, we recover the well-known result that the elastic scattering differential cross sections with and without laser field for a hydrogen atom by electron and positron impact are the same (Greiner and Reinhardt. Quantum Electrodynamics, 2nd ed., Springer Verlag, New York, Berlin, Heidelberg. 1994). The numerical results reveal that the differential cross section for positron – hydrogen atom scattering is significantly reduced with the increase of the electric field strength.

QED and X-Ray Pulsars

1985 ◽  
Vol 6 (2) ◽  
pp. 211-214 ◽  
Author(s):  
Michelle C. Allen ◽  
D. B. Melrose ◽  
A. J. Parle
Keyword(s):  
Neutron Stars ◽  
Cross Sections ◽  
Quantum Electrodynamics ◽  
Particle Interactions ◽  
Electron Collisions ◽  
X Ray ◽  
Electron Photon ◽  
Photon Interactions

AbstractTechniques in QED (quantum electrodynamics) have been developed previously (see for example Melrose and Parle 1983) allowing one to treat electron-photon and photon-photon interactions exactly in the magnetized vacuum and allowing one to include the effects of a medium. These techniques are extended to include particle-particle interactions. Exact cross-sections for electron-electron collisions are derived and compared with known expressions. Such calculations have application in studies of the formation and transfer of radiation in the atmospheres surrounding neutron stars.

Introduction to Quantum Field Theory

2019 ◽  
Author(s):  
Horatiu Nastase
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Cross Sections ◽  
Quantum Electrodynamics ◽  
Particle Physics ◽  
Vector Fields ◽  
Quantum Field ◽  
Fermionic Fields ◽  
Key Aspects ◽  
Scattering Cross Sections

Quantum Field Theory provides a theoretical framework for understanding fields and the particles associated with them, and is the basis of particle physics and condensed matter research. This graduate level textbook provides a comprehensive introduction to quantum field theory, giving equal emphasis to operator and path integral formalisms. It covers modern research such as helicity spinors, BCFW construction and generalized unitarity cuts; as well as treating advanced topics including BRST quantization, loop equations, and finite temperature field theory. Various quantum fields are described, including scalar and fermionic fields, Abelian vector fields and Quantum ElectroDynamics (QED), and finally non-Abelian vector fields and Quantum ChromoDynamics (QCD). Applications to scattering cross sections in QED and QCD are also described. Each chapter ends with exercises and an important concepts section, allowing students to identify the key aspects of the chapter and test their understanding.

Bound-free electron–positron pair production mechanism at an electron-ion collider

2017 ◽  
Vol 26 (09) ◽  
pp. 1750055
Author(s):  
M. Y. Şengül
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
Quantum Electrodynamics ◽  
Ion Beam ◽  
Loss Mechanism ◽  
Beam Loss ◽  
Electron Positron ◽  
The Cross ◽  
Free Pair ◽  
Structure Of Matter

The aims of building electron-ion colliders (EICs) are to reach high collision luminosity and polarization, to search on the structure and the interactions of gluon-matter, to investigate the spin structure of matter, to probe the behavior of parton densities in the nuclear medium, and to study and to test quantum chromodynamics (QCD). In this work, we have calculated the cross-sections of the ion beam loss mechanism at EICs via bound-free pair production (BFPP) mechanism. The BFPP is important for the detector design because of its large cross-sections that will give rise to decrease the luminosity of the accelerators. We have done the cross-section calculations for BFPP in the framework of quantum electrodynamics (QED) by using the lowest-order perturbation theory for three different EICs that are mentioned below.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

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