Search for Higgs Bosons and Supersymmetric Particles in Tau Final States

Elementary particle physics tries to find an answer to no minor question: What is our universe made of? To our current knowledge, the elementary constituents of matter are quarks and leptons, which interact via four elementary forces: electromagnetism, strong force, weak force and gravity. All forces, except gravity, can be described in one framework, the Standard Model of particle physics. The model's name reflects its exceptional success in describing all available experimental high energy physics data to high precision up to energies of about 100 GeV. An exception is given by the neutrino masses but even these can be integrated into the model. The Standard Model is based on the requirement of invariance of all physics processes under certain fundamental symmetry transformations. The consideration of these symmetries leads naturally to the correct description of the electromagnetic, weak and strong forces as the exchange of interaction particles, the gauge bosons. However, this formalism has the weakness that it only allows for massless particles. In order to obey the symmetries, a way to introduce the particle masses is given by the Higgs mechanism, which predicts the existence of the only particle of the Standard Model which has yet to be observed: the Higgs boson. In spite of the success of the Standard Model, it has to be considered as a low energy approximation of a more profound theory for various reasons. For example, the underlying theory is expected to allow for an integration of gravity into the framework and to provide a valid particle candidate for the dark matter in our universe. Furthermore, a solution has to be found to the problem that the Higgs boson as a fundamental scalar is sensitive to large radiative corrections driving its mass to the Planck scale of 10{sup 19} GeV. Several models have been proposed to address the remaining open questions of the Standard Model. Currently, the most promising extension of the Standard Model is Supersymmetry, which provides elegant solutions to the named problems by introducing a supersymmetric partner to each Standard Model particle. The superpartners of the matter particles are called squarks and sleptons, while the superpartners of the interaction particles are called gauginos. The mass eigenstates of the gauginos are referred to as charginos and neutralinos, according to their electric charge. Since the predicted supersymmetric particles have not yet been observed, Supersymmetry, if it exists in nature, has to be broken in such a way that the masses of Standard Model particles and of their superpartners differ. During the last decades, the energies accessible to experiments has steadily increased. The Tevatron Accelerator at the Fermi National Accelerator Laboratory, with the two multipurpose experiments D0 and CDF, provides currently the highest center-of-mass energy ever reached in experiments using collisions of protons and antiprotons ({radical}s = 1.96 TeV). The study of the particle collisions allows probing of predictions of the Standard Model and its extensions, e.g. Supersymmetry

Search for beyond the standard model Higgs bosons at D0

Despite its tremendous success in describing the available high energy physics data to high precision, the standard model (SM) of particle physics is known to be incomplete. The most popular extension of the SM is supersymmetry. It provides elegant solutions to various problems of the SM, e.g. the fact that in the SM the mass of the Higgs boson is sensitive to large radiative corrections driving its mass to the Planck scale. The reported results are based on data samples of proton-antiproton collisions at a center-of-mass energy of {radical}s = 1.96 TeV provided by the Tevatron. The analyzed data is recorded by the D0 detector [1]. All reported limits are calculated at the 95% confidence level (CL) based on the modified frequentist approach [2]. Recent searches by the D0 collaboration for Higgs bosons in extensions of the Standard Model at the Tevatron are reported with emphasis on neutral Higgs bosons in supersymmetry

An integrated shortfall measure for Basel III

We propose a new method for measuring how far away banks are from complying with a multi-ratio regulatory framework. We suggest measuring the efforts a bank has to make to reach compliance as an additional portfolio which is derived from a microeconomic banking model. This compliance portfolio provides an integrated measure of the shortfalls resulting from a new regulatory framework. Our method complements the descriptive reporting of individual shortfalls per ratio when monitoring banks' progress toward compliance with a new regulatory framework. We apply our concept to a sample of 46 German banks in order to quantify the effects of the interdependencies of the Basel III capital and liquidity requirements. Comparing our portfolio approach to the shortfalls reported in the Basel III monitoring, we find that the reported shortfalls tend to underestimate the required capital and to overestimate of the required stable funding. However, compared to the overall level of the reported shortfalls, the effects resulting from the interdepen- dencies of the Basel III ratios are found to be rather small