Precision Cross Section Measurements and Searches for New Physics with ATLAS

The nature of the fundamental constituents of matter and their interactions have inspired mankind at least since the days, when the idea of indivisible elementary particles was formulated by ancient Greek philosophers. Today we stand at a point, where the best known theory - the Standard Model (SM) - has been tested over the last 30 years with a very high precision in many experiments at large particle accelerators. Even though the SM has been able to describe all discovered effects, many miracles remain to be solved. For example astrophysical observations show, that the matter we know and have studied up to now makes up only 1/20th of the matter content of the universe. The Large Hadron Collider (LHC) is the highest energy particle accelerator ever build. It collides protons at energies at least 7 times higher than in every other facility. The complex ATLAS experiment was designed to register the outcome of these violent collisions. With the help of LHC and ATLAS we may be able to solve some of the open questions within a few years. One solution may be so called Super Symmetric theories, where every fundamental particle we know today is assigned a partner. If these new particles exists, they should be discovered at the LHC and their properties will be studied. The first task will be to understand the properties of the ATLAS experiment, one of the most complex technical devices ever build. It is approximately 26 m long, 20 m high, and weighs 7000 tons. Still, some of the inner components, the silicon track detectors, have to be positioned with an accuracy of a few 1/1000 of a millimetre. Together with the experts in Liverpool, who build a part of these detectors, I will determine corrections to achieve the best possible measuring accuracy. The next task will be accurate measurements of the production of known Standard Model particles, so called W bosons. This measurement will show how well we understand the experimental apparatus, the Standard Model, and the composition of the proton from elementary particles. Using all the information we have today, we are able to predict the rate with which the W bosons are produced, so we can compare the measurements to our expectation. Finally, I will look for the particles predicted by theories that go beyond the Standard Model. If any of these new particles are produced, they will decay rapidly to other known particles which can be registered by ATLAS. I propose to concentrate my search on decays, where an electron and its antimatter partner, the positron, are produced together with other highly energetic objects (so called jets) and the candidate particle for the dark matter. Theorists tell us, that this kind of events will happen for many different types of new models, but the Standard Model predicts very low rates. The decay products will carry enough information of their parents, so the properties of the fundamental theory can be determined. I am looking forward to contributing to this exciting scientific program, which may significantly enhance our understanding about the basic building blocks and laws of nature.