Group of Hubert Spiesberger

Members
H. Spiesberger, A. Weber

Progress in the understanding of the fundamental interactions of elementary particles requires a close collaboration of experimental and theoretical research. The role of theoretical physics is to provide detailed predictions for scattering and decay processes with elementary particles to a precision that matches the experimental possibilities. Testing the phenomenology of elementary particle properties in high energy scattering processes against theoretical predictions is a first step in the search for new particles and new phenomena.

Phenomenology of the Eletroweak and Strong Interactions

The evaluation of theoretical predictions for high-energy particle phenomenology requires, with only a few exceptions, perturbation theory. Important steps in obtaining predictions are

  • The development of automatic techniques for analytic calculations
  • Renormalization and factorisation of singularities
  • Development of Monte Carlo simulation programs

Applications which I considered in my recent work are

Search for Physics Beyond the Standard Model

Despite of its great success, the Standard Model of the electroweak interactions suffers from a number of deficiencies that motivate the study of extensions. Popular models of “New Physics” which go beyond the Standard Model include

  • Supersymmetry
  • New particles like leptoquarks
  • New interactions, e.g. violating lepton number
  • Extra dimensions

A detailed knowledge of how models beyond the Standard Model signal their presence in scattering processes at high energies is needed if they are not to be overlooked in the bulk of standard physics. Experiments in high energy physics are often complementary in their sensitivity for new physics and combined analyses taking into account a broad spectrum of phenomena are necessary. Theoretical studies can provide prescriptions for experimental tests of new models. A recent review was presented at the XIV International Workshop on Deep Inelastic Scattering 2006.

Electrical Impedance Tomography

EIT is an imaging technique of medical diagnostics, in which one tries to obtain information on the conductivity distribution in the interior of a body by measuring currents and voltages at the surface of the body. Since different types of tissue have different specific conductivities, EIT would provide a non-invasive complementary alternative to more conventional imaging techniques.

We are building an electrical impedance tomograph for applications in medical diagnostics such as imaging the interior of a human chest, or mammography. A challenging part of the project is the development of an image reconstruction algorithm. This requires a good understanding of inverse, ill-posed problems. Possible directions to a solution and recent promising test measurements have been described in the thesis by Andrea Almasy. Our activities are embedded in a trans-regional project supported by the German BMBF (REIT: Regularisierungsverfahren für die elektrische Impedanztomographie in Medizin und Geowissenschaften).

The general ideas of the project are also described in a presentation at the Transfercafe (Mainz, Proviantamt, starting March 2011)