scholarly journals A New Family of Interactions between Clothed Particles in QED

2021 ◽  
Vol 66 (10) ◽  
pp. 833
Author(s):  
A. Arslanaliev ◽  
Y. Kostylenko ◽  
O. Shebeko
Keyword(s):  
Perturbation Theory ◽  
Compton Scattering ◽  
Quantum Electrodynamics ◽  
Matrix Elements ◽  
Energy Shell ◽  
New Family ◽  
Shell Matrix ◽  
Electron Positron ◽  
S Matrix ◽  
Novel Interactions

The method of unitary clothing transformations (UCTs) has been applied to the quantum electrodynamics (QED) by using the clothed particle representation (CPR). Within CPR, the Hamiltonian for interacting electromagnetic and electron-positron fields takes the form in which the interaction operators responsible for such two-particle processes as e−e− → e−e−, e+e+ → e+e+, e−e+ → e−e+, e−e+ → yy, yy → e−e+, ye− → ye−, and ye+ → ye+ are obtained on the same physical footing. These novel interactions include the off-energy-shell and recoil effects (the latter without any expansion in (v/c)2-series) and their on-energy shell matrix elements reproduce the well-known results derived within the perturbation theory based on the Dyson expansion for the S-matrix (in particular, the Møller formula for the e−e−-scattering, the Bhabha formula for e−e+-scattering, and the Klein–Nishina one for the Compton scattering).

scholarly journals Normalizability analysis of the generalized quantum electrodynamics from the causal point of view

2017 ◽  
Vol 32 (27) ◽  
pp. 1750165 ◽  
Author(s):  
R. Bufalo ◽  
B. M. Pimentel ◽  
D. E. Soto
Keyword(s):  
Perturbation Theory ◽  
Physical Model ◽  
Gauge Invariance ◽  
Quantum Electrodynamics ◽  
Lorentz Invariance ◽  
Point Of View ◽  
Inductive Method ◽  
S Matrix ◽  
Causal Approach

The causal perturbation theory is an axiomatic perturbative theory of the S-matrix. This formalism has as its essence the following axioms: causality, Lorentz invariance and asymptotic conditions. Any other property must be showed via the inductive method order-by-order and, of course, it depends on the particular physical model. In this work we shall study the normalizability of the generalized quantum electrodynamics in the framework of the causal approach. Furthermore, we analyze the implication of the gauge invariance onto the model and obtain the respective Ward–Takahashi–Fradkin identities.

scholarly journals QED in the clothed-particle representation: a fresh look at positronium properties treatment

2020 ◽  
Author(s):  
Yan Kostylenko ◽  
Adam Arslanaliev ◽  
Aleksandr V. Shebeko
Keyword(s):  
Decay Rate ◽  
Distinctive Feature ◽  
Ground State ◽  
Quantum Electrodynamics ◽  
Bound States ◽  
Analytical Expression ◽  
New Family ◽  
Electron Positron ◽  
Electrons And Positrons

We have extended our previous applications of the method of unitary clothing transformations (UCTs) in mesodynamics [1,2] to quantum electrodynamics (QED) [3,4]. An analytical expression for the QED Hamiltonian in the clothed-particle representation (CPR) has been derived. Its distinctive feature is the appearance of a new family of the Hermitian and energy independent interaction operators built up in the e^2e2-order for the clothed electrons and positrons instead the primary canonical interaction between electromagnetic and electron-positron fields. The problem of describing the bound states in QED in case of the positronium system has been considered. The first correction to the energy of the ground state of the para-positronium and its decay rate to two photons has been calculated by using the new interaction operators.

QUANTUM-ELECTRODYNAMIC PROCESSES IN A RADIATION-DOMINATED ROBERTSON-WALKER UNIVERSE

1992 ◽  
Vol 07 (09) ◽  
pp. 2055-2086 ◽  
Author(s):  
I.L. BUCHBINDER ◽  
L.I. TSAREGORODTSEV
Keyword(s):  
Quantum Electrodynamics ◽  
Line Element ◽  
Total Probability ◽  
Matrix Formalism ◽  
Differential Probability ◽  
Electron Positron ◽  
S Matrix ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Electron Positron Pair

Quantum electrodynamics in an expanding Robertson-Walker universe with the line element ds2=dt2 – a2(t)(dx2+dy2+dz2) (radiation-dominated universe) is considered. The differential probability of bremsstrahlung of an electron in the external gravitational field and the differential probability of an electron-positron pair and photon creation from the vacuum are calculated by using the perturbative S-matrix formalism. The behavior of these probabilities in different kinematic regions is investigated. The total probabilities are shown to be finite. In conclusion, the total probability of a pair and photon creation from vacuum We is compared with the total probability of pair production due to an expansion of the universe W0. The comparison shows that We=1.9·10−2W0 at about the Compton time of an electron.

GLUEBALL AND MESON SCATTERING IN COMPACT QED2+1 LATTICE GAUGE THEORY

1994 ◽  
Vol 05 (02) ◽  
pp. 335-337
Author(s):  
A.M. CHAARA ◽  
H. KRÖGER ◽  
J. POTVIN
Keyword(s):  
Perturbation Theory ◽  
Gauge Theory ◽  
Strong Coupling ◽  
Cross Sections ◽  
Lattice Gauge Theory ◽  
Hamiltonian Formulation ◽  
Matrix Elements ◽  
Lattice Gauge ◽  
S Matrix ◽  
Scattering Cross Sections

We study glueball and meson scattering in compact QED2+1 gauge theory in a Hamiltonian formulation on a momentum lattice. We compute S-matrix elements and scattering cross sections and compare our results with strong coupling perturbation theory

scholarly journals Gauge-Independent Calculation of S-Matrix Elements in Quantum Electrodynamics

1983 ◽  
Vol 69 (4) ◽  
pp. 1225-1235 ◽  
Author(s):  
Y. Kakudo ◽  
Y. Taguchi ◽  
A. Tanaka ◽  
K. Yamamoto
Keyword(s):  
Quantum Electrodynamics ◽  
Matrix Elements ◽  
S Matrix ◽  
Independent Calculation

scholarly journals Discrete phase space - III: The divergence-free S-matrix elements

2010 ◽  
Vol 88 (2) ◽  
pp. 111-130
Author(s):  
A. Das
Keyword(s):  
Phase Space ◽  
Vertex Function ◽  
Quantum Electrodynamics ◽  
Final Section ◽  
Matrix Elements ◽  
S Matrix ◽  
Feynman Rules ◽  
Discrete Phase ◽  
Infrared Divergences ◽  
Special Case

In the arena of the discrete phase space and continuous time, the theory of S-matrix is formulated. In the special case of quantum electrodynamics (QED), the Feynman rules are precisely developed. These rules in the four-momentum turn out to be identical to the usual QED, except for the vertex function. The new vertex function is given by an infinite series that can only be treated in an asymptotic approximation at the present time. Preliminary approximations prove that the second-order self-energies of a fermion and a photon in the discrete model have convergent improper integrals. In the final section, a sharper asymptotic analysis is employed. It is proved that in case where the number of external photon or fermion lines is at least one, then the S-matrix elements converge in all orders. Moreover, there are no infrared divergences in this formulation.

Energy, Information, and Superluminal Speed in Quantum Electrodynamics

2020 ◽  
pp. 27-33
Author(s):  
Boris A. Veklenko
Keyword(s):  
Electromagnetic Field ◽  
Perturbation Theory ◽  
Quantum Electrodynamics ◽  
Excited Atom ◽  
Standard Quantum ◽  
Energy Information

Without using the perturbation theory, the article demonstrates a possibility of superluminal information-carrying signals in standard quantum electrodynamics using the example of scattering of quantum electromagnetic field by an excited atom.

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