Gerhard Soff

AMEGIC++ 1.0: A Matrix element generator in C++

The new matrix element generator AMEGIC++ is introduced, dedicated to describe multi-particle production in high energy particle collisions. It automatically generates helicity amplitudes for the processes under consideration and constructs suitable, efficient integration channels for the multi-channel phase space integration. The corresponding expressions for the amplitudes and the integrators are stored in library files to be linked to the main program.

QED corrections in heavy atoms

Abstract The comparison of theory and experiment for energy levels of strongly bound electrons provides a critical test of quantum electrodynamics in strong fields. A theoretical evaluation of the vacuum polarization and self energy radiative corrections to electron binding energies in heavy atoms is given. The calculations are done to all orders in the strength of the external field of the nucleus Zα . The influence of nuclear size and structure effects is investigated. The results for the Lamb shift are compared to the experimental data.

Net-to-leading order QCD corrections for the B0B0 mixing with an extended Higgs sector

Abstract We present a calculation of the B 0 B 0 mixing including next-to-leading order (NLO) QCD corrections within the Two-Higgs Doublet Model (2HDM). The QCD corrections at NLO are contained in the factor denoted by η2 which modifies the result obtained at the lowest order of perturbation theory. In the Standard Model case, we confirm the results for η2 obtained by Buras, Jamin and Weisz [Nucl. Phys. B 347 (]990) 49]1. The factor η2 is gauge and renormalization prescription invariant and it does not depend on the infrared behaviour of the theory, which constitutes an important test of the calculations. The NLO calculations within the 2HDM enhance the LO result up to 18%, which affects the correlation between My and Vtd.

Dual kinetic balance approach to basis-set expansions for the dirac equation.

A new approach to finite basis sets for the Dirac equation is developed. It does not involve spurious states and improves the convergence properties of basis-set calculations. Efficiency of the method is demonstrated for finite basis sets constructed from B splines by calculating the one-loop self-energy correction for a hydrogenlike ion.

QED calculation of the n= 1 and n=2 energy levels in He-like ions

We perform ab initio QED calculations of energy levels for the

An Effective model of the quark - gluon plasma with thermal parton masses

n=1

The Equation of state of deconfined matter at finite chemical potential in a quasiparticle description

and

A modified cluster-hadronisation model

n=2

Dirac-Fock-Slater calculations for the elements Z=100, fermium, to Z=173

states of He-like ions with the nuclear charge in the range

Calculation of the Electron Self Energy for Low Nuclear Charge

Z=12\text{\char21{}}100