On Schwinger's formula for pair production

We present some comments on Schwinger's calculation of electron-positron production in a prescribed constant electric field. The range of validity of 2 Im \mathcal{L}^(1)(E) is discussed thoroughly and limiting cases are provided

The Coulomb Green's Function in Two Dimensions

We consider the two-dimensional non-relativistic Coulomb problem with the aid of the momentum space construction of the associated Green's function. Our presentation has precursors in three dimensions. It is mainly Schwinger's approach which we advocate and project onto two dimensions.Comment: 20 pages, LaTe

The Cofounder of Quantum Field Theory: Pascual Jordan

A comparative study is undertaken that brings to light the two different methods of how to treat the many-body problem in quantum field theory. The two main researchers who published the first versions of how to quantize a many-body assembly were P. Jordan and P.A.M. Dirac. What they understood by the so-called "second quantization" will be the subject of the paper. We will argue that it is Jordan's field operator approach that until now constitutes the basis of any work in quantum field theory

Flavor Condensate and Vacuum (In-)Stability in QED_(2+1)

In this letter we study (2+1)-dimensional QED. The first part contains the computation of the flavor symmetry-breaking condensate and its relation to the trace of the energy-momentum tensor, while the second part is concerned with the computation of the effective action allowing for non-constant static external magnetic fields. We do not find that space derivatives in the magnetic field lower the energy of the ground state as compared to a constant field configuration.Comment: 14 pages, uses REVTe

Modelling dependency in multivariate paired comparisons:a log-linear approach.

A log-linear representation of the Bradley-Terry model is presented for multivariate paired comparison data, where judges are asked to compare pairs of objects on more than one attribute. By converting such data to multiple binomial responses, dependencies between the decisions of the judges as well as possible association structures between the attributes can be incorporated in the model, providing an advantage over parallel univariate analyses of individual attributes. The approach outlined gives parameters which can be interpreted as (conditional) log–odds and log–odds ratios. As the model is a generalised linear model, parameter estimation can use standard software and the GLM framework can be used to test hypotheses on these parameters

Analytical results for the confinement mechanism in QCD_3

We present analytical methods for investigating the interaction of two heavy quarks in QCD_3 using the effective action approach. Our findings result in explicit expressions for the static potentials in QCD_3 for long and short distances. With regard to confinement, our conclusion reflects many features found in the more realistic world of QCD_4.Comment: 24 pages, uses REVTe