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.

scholarly journals QUANTUM ELECTRODYNAMICS OF RELATIVISTIC BOUND STATES WITH CUTOFFS

2004 ◽  
Vol 01 (02) ◽  
pp. 271-314 ◽  
Author(s):  
JEAN-MARIE BARBAROUX ◽  
MOUEZ DIMASSI ◽  
JEAN-CLAUDE GUILLOT
Keyword(s):  
Current Density ◽  
Coulomb Potential ◽  
Ground State ◽  
Quantum Electrodynamics ◽  
Bound States ◽  
Coupling Constants ◽  
Relativistic Electrons ◽  
Small Coupling ◽  
Electrons And Positrons ◽  
Relativistic Bound States

We consider a Hamiltonian with ultraviolet and infrared cutoffs, describing the interaction of relativistic electrons and positrons in the Coulomb potential with photons in Coulomb gauge. The interaction includes both interaction of the current density with transversal photons and the Coulomb interaction of charge density with itself. We prove that the Hamiltonian is self-adjoint and has a ground state for sufficiently small coupling constants.

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).

SIMULTANEOUS CREATION OF ELECTRON–POSITRON PAIRS AND PHOTONS IN ROBERTSON–WALKER UNIVERSES WITH STATICALLY BOUNDED EXPANSION

1992 ◽  
Vol 07 (12) ◽  
pp. 2695-2712 ◽  
Author(s):  
K.-H. LOTZE
Keyword(s):  
Quantum Electrodynamics ◽  
Particle Creation ◽  
Conformally Flat ◽  
Coupling Constant ◽  
Zeroth Order ◽  
Attenuation Effect ◽  
Interacting Particle ◽  
Electron Positron ◽  
Electrons And Positrons ◽  
Bounded Expansion

We present, based upon quantum electrodynamics in Robertson–Walker flat universes, a thorough analysis of the creation of mutually interacting electron–positron pairs and photons from vacuum. Therefore we discuss at least qualitatively all processes contributing to the number densities of created particles up to the second order in the coupling constant. For two particular expansion laws with Minkowskian in respectively in and out regions, we obtain exact solutions to the Dirac equation and investigate in detail the process of simultaneous creation of electron–positron pairs and photons and the related attenuation effect for fermionic particles. This is done for electrons and positrons which have nonrelativistic momenta at Compton time in rapidly expanding universes. The results are compared with the zeroth-order creation of electron–positron pairs. Despite being smaller by a factor of roughly [Formula: see text], the interacting-particle creation is important mainly as a source of photons even in conformally flat universes.

scholarly journals Dominance of γ-γ electron-positron pair creation in a plasma driven by high-intensity lasers

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yutong He ◽  
Thomas G. Blackburn ◽  
Toma Toncian ◽  
Alexey V. Arefiev
Keyword(s):  
High Intensity ◽  
Quantum Electrodynamics ◽  
Linear Process ◽  
Pair Creation ◽  
Jet Formation ◽  
Beam Laser ◽  
Electron Positron ◽  
Electrons And Positrons ◽  
Laser Facility ◽  
Basic Prediction

AbstractCreation of electrons and positrons from light alone is a basic prediction of quantum electrodynamics, but yet to be observed. Our simulations show that the required conditions are achievable using a high-intensity two-beam laser facility and an advanced target design. Dual laser irradiation of a structured target produces high-density γ rays that then create > 108 positrons at intensities of 2 × 1022 Wcm−2. The unique feature of this setup is that the pair creation is primarily driven by the linear Breit-Wheeler process (γγ → e+e−), which dominates over the nonlinear Breit-Wheeler and Bethe-Heitler processes. The favorable scaling with laser intensity of the linear process prompts reconsideration of its neglect in simulation studies and also permits positron jet formation at experimentally feasible intensities. Simulations show that the positrons, confined by a quasistatic plasma magnetic field, may be accelerated by the lasers to energies >200 MeV.

CRITICAL LINE AND BETHE-SALPETER EQUATION IN STRONG-COUPLING QED WITH FOUR-FERMION INTERACTIONS

1989 ◽  
Vol 04 (07) ◽  
pp. 605-612 ◽  
Author(s):  
M. INOUE ◽  
T. MUTA ◽  
T. OCHIUMI
Keyword(s):  
Symmetry Breaking ◽  
Strong Coupling ◽  
Chiral Symmetry ◽  
Quantum Electrodynamics ◽  
Phase Structure ◽  
Bound States ◽  
Critical Line ◽  
Chiral Symmetry Breaking ◽  
Electron Positron ◽  
Symmetric Phase

On the basis of Bethe-Salpeter equations for electron-positron bound states in strong-coupling quantum electrodynamics with additional four-fermion interactions, the formula for the critical line dividing the chiral-symmetry-breaking phase from the symmetric phase is derived. The beta functions near the critical line are calculated explicitly and the phase structure is discussed based on these beta functions.

scholarly journals PAULI–FIERZ MODEL WITH KATO-CLASS POTENTIALS AND EXPONENTIAL DECAYS

2010 ◽  
Vol 22 (10) ◽  
pp. 1181-1208 ◽  
Author(s):  
TAKERU HIDAKA ◽  
FUMIO HIROSHIMA
Keyword(s):  
Ground State ◽  
Quantum Electrodynamics ◽  
Bound States ◽  
The Self ◽  
Nonrelativistic Quantum ◽  
Kato Class ◽  
Symmetric Semigroup

Generalized Pauli–Fierz Hamiltonian with Kato-class potential K PF in nonrelativistic quantum electrodynamics is defined and studied by a path measure. K PF is defined as the self-adjoint generator of a strongly continuous one-parameter symmetric semigroup and it is shown that its bound states spatially exponentially decay pointwise and the ground state is unique.

Spin-Forbidden Excitation Enables Infrared Photoredox Catalysis

2020 ◽  
Author(s):  
Tomislav Rovis ◽  
Benjamin D. Ravetz ◽  
Nicholas E. S. Tay ◽  
Candice Joe ◽  
Melda Sezen-Edmonds ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Intersystem Crossing ◽  
Photoredox Catalysis ◽  
Infrared Irradiation ◽  
Triplet Excitation ◽  
New Family ◽  
Ir Light

We describe a new family of catalysts that undergo direct ground state singlet to excited state triplet excitation with IR light, leading to photoredox catalysis without the energy waste associated with intersystem crossing. The finding allows a mole scale reaction in batch using infrared irradiation.

scholarly journals Dynamical Symmetries of the H Atom, One of the Most Important Tools of Modern Physics: SO(4) to SO(4,2), Background, Theory, and Use in Calculating Radiative Shifts

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1323 ◽  
Author(s):  
G. Jordan Maclay
Keyword(s):  
Hydrogen Atom ◽  
Quantum Electrodynamics ◽  
Particle Physics ◽  
Bound States ◽  
Integrated Treatment ◽  
Invariance Group ◽  
Elementary Particle Physics ◽  
Background Theory ◽  
Modern Physics ◽  
History Of

Understanding the hydrogen atom has been at the heart of modern physics. Exploring the symmetry of the most fundamental two body system has led to advances in atomic physics, quantum mechanics, quantum electrodynamics, and elementary particle physics. In this pedagogic review, we present an integrated treatment of the symmetries of the Schrodinger hydrogen atom, including the classical atom, the SO(4) degeneracy group, the non-invariance group or spectrum generating group SO(4,1), and the expanded group SO(4,2). After giving a brief history of these discoveries, most of which took place from 1935–1975, we focus on the physics of the hydrogen atom, providing a background discussion of the symmetries, providing explicit expressions for all of the manifestly Hermitian generators in terms of position and momenta operators in a Cartesian space, explaining the action of the generators on the basis states, and giving a unified treatment of the bound and continuum states in terms of eigenfunctions that have the same quantum numbers as the ordinary bound states. We present some new results from SO(4,2) group theory that are useful in a practical application, the computation of the first order Lamb shift in the hydrogen atom. By using SO(4,2) methods, we are able to obtain a generating function for the radiative shift for all levels. Students, non-experts, and the new generation of scientists may find the clearer, integrated presentation of the symmetries of the hydrogen atom helpful and illuminating. Experts will find new perspectives, even some surprises.

scholarly journals Electromagnetic transition form factors of baryons in a relativistic Faddeev approach

2018 ◽  
Vol 181 ◽  
pp. 01013 ◽  
Author(s):  
Reinhard Alkofer ◽  
Christian S. Fischer ◽  
Hèlios Sanchis-Alepuz
Keyword(s):  
Ground State ◽  
Bound States ◽  
Body Wave ◽  
Form Factors ◽  
Wave Functions ◽  
Electromagnetic Form Factors ◽  
Transition Form ◽  
Electromagnetic Transition ◽  
Three Body ◽  
Gluon Interaction

The covariant Faddeev approach which describes baryons as relativistic three-quark bound states and is based on the Dyson-Schwinger and Bethe-Salpeter equations of QCD is briefly reviewed. All elements, including especially the baryons’ three-body-wave-functions, the quark propagators and the dressed quark-photon vertex, are calculated from a well-established approximation for the quark-gluon interaction. Selected previous results of this approach for the spectrum and elastic electromagnetic form factors of ground-state baryons and resonances are reported. The main focus of this talk is a presentation and discussion of results from a recent investigation of the electromagnetic transition form factors between ground-state octet and decuplet baryons as well as the octet-only Σ0 to Λ transition.

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