Self-energy correction to the hyperfine structure splitting of hydrogenlike atoms

A first testing ground for QED in the combined presence of a strong Coulomb field and a strong magnetic field is provided by the precise measurement of the hyperfine structure splitting of hydrogenlike 209Bi. We present a complete calculation of the one-loop self-energy correction to the first-order hyperfine interaction for various nuclear charges. In the low-Z regime we almost perfectly agree with the Z alpha expansion, but for medium and high Z there is a substantial deviation

Kvantmekaniken och vårt universum : Lever vi i en singel eller multipel värld?

Den traditionella kvantmekaniken började utvecklas under 1920-talet, framförallt av den s.k. Köpenhamnsskolan under ledning av dansken Niels Bohr och personer i hans omgivning. Den var långt ifrån okontroversiell, och välkänd är dispyten mellan Bohr och Albert Einstein som pågick under flera decennier. Under 1950-talet introducerades en alternativ version av kvantmekaniken av Hugh Everett, då doktorand vid Princeton-universitetet. Denna version utvecklades sedermera till en s.k. fler-världs- eller multi-worlds-modell, som undvek vissa avsvårigheterna med Köpenhamns-modellen men som i stället introducerade nya sådana.Den gängse uppfattningen är att världen skapades genom en stor explosion, Big Bang, men det finns även teorier om att vårt universum skapades genom en explosion i ett tidigare existerande större universum. Det kan då finnas flera universa vid sidan om vårt, ett multiuniversum. Denna teori har kopplingar till Everetts multi-worlds-modell. Vi kan idag inte säga vilken kvantmekanisk modell som är mer korrekt.The traditional form of quantum mechanics started to develop in the 1920's, particularly within the Copenhagen school under the leadership of Niels Bohr and the people around him. This theory was by no means uncontroversial, and it is known to have caused a dispute between Bohr and Albert Einstein, which went on for several decades. An alternative formulation of quantum mechanics was introduced during the 1950's by Hugh Everett, who was then a research student at the Princeton university. His model was later to be developed into a so-called Many-Worlds model, which avoids certain difficulties inherent in the Copenhagen model, but only does so at the expense of introducing a number of new ones.The theory that our world was created by a great explosion, the Big Bang, is generally accepted; however, according to other theories our universe was created inside an already existing universe. It may then be possible that, together with our universe, there exist several others, forming a multi-universe or multiverse. This theory has connections to the many worlds model of Everett. Today it cannot be decided which interpretation of quantum mechanics is the more corre

Relativistic Many-Body Theory: A New Field-Theoretical Approach /

Relativistic Many-Body Theory treats — for the first time — the combination of relativistic atomic many-body theory with quantum-electrodynamics (QED) in a unified manner. This book can be regarded as a continuation of the book by Lindgren and Morrison, Atomic Many-Body Theory (Springer 1986), which deals with the non-relativistic theory of many-electron systems, describing several means of treating the electron correlation to essentially all orders of perturbation theory. The treatment of the present book is based upon quantum-field theory, and demonstrates that when the procedure is carried to all orders of perturbation theory, two-particle systems are fully compatible with the relativistically covariant Bethe-Salpeter equation. This procedure can be applied to arbitrary open-shell systems, in analogy with the standard many-body theory, and it is also applicable to systems with more than two particles. Presently existing theoretical procedures for treating atomic systems are, in several cases, insufficient to explain the accurate experimental data recently obtained, particularly for highly charged ions. This shortcoming is expected to be due to omission of combined QED-correlational effects, included in the new unified procedure. All methods treated in Relativistic Many-Body Theory are illustrated with numerical examples. The main text is divided into three parts. In Part I, the standard time-independent and time-dependent perturbation procedures are reviewed.  Part II describes three methods for QED calculations, a) the standard S-matrix formulation, b) the Two-times Green’s-function method, developed by the St Petersburg Atomic Theory group, and c) the Covariant-evolution-operator  (CEO) method, recently developed by the Gothenburg Atomic Theory group. In Part III, the CEO method is combined with electron correlation to arbitrary order to a unified MBPT-QED procedure. In this procedure the electron correlation can be included to high order, and therefore this procedure is expected to lead to faster convergence than treating the BS equation order by order. Ingvar Lindgren is also the author of the highly-cited "Atomic Many-Body Theory" book published by Springer

Relativistic many-body theory: a new field-theoretical approach

This revised second edition of the author’s classic text offers readers a comprehensively updated review of relativistic atomic many-body theory, covering the many developments in the field since the publication of the original title.  In particular, a new final section extends the scope to cover the evaluation of QED effects for dynamical processes. The treatment of the book is based upon quantum-field theory, and demonstrates that when the procedure is carried to all orders of perturbation theory, two-particle systems are fully compatible with the relativistically covariant Bethe-Salpeter equation. This procedure can be applied to arbitrary open-shell systems, in analogy with the standard many-body theory, and it is also applicable to systems with more than two particles. Presently existing theoretical procedures for treating atomic systems are, in several cases, insufficient to explain the accurate experimental data recently obtained, particularly for highly charged ions. The main text is divided into three parts. In Part I, the standard time-independent and time-dependent perturbation procedures are reviewed. This includes a new section at the end of chapter 2 concerning the so-called ”Fock-space procedure” or ”Coulomb-only procedure” for relativistic-QED calculations. This is a procedure on an intermediate level, frequently u sed in recent time by chemists on molecular systems, where a full QED treatment is out of question.  Part II describes three methods for QED calculations, a) the standard S-matrix formulation, b) the Two-times Green’s-function method, developed by the St Petersburg Atomic Theory group, and c) the Covariant-evolution operator (CEO) method, recently developed by the Gothenburg Atomic Theory group.  In Part III, the CEO method is combined with electron correlation to arbitrary order to a unified MBPT-QED procedure. The new Part IV includes two new chapters dealing with dynamical properties and how QED effects can be evaluated for such processes. This part is much needed as there has been an increasing interest in the study of QED effects for such processes. All methods treated in the book are illustrated with numerical examples, making it a text suitable for advanced students new to the field and a useful reference for established researchers