Charged current couplings in #tau# decay

We discuss the impact of the recent measurements of the Michel parameter in #tau# decay. These measurements are used to extract limits on the charged current couplings beyond the Standard Model, first in a model independent way and then with some additional but very general assumptions. The measurements substantiate the Standard Model V-A hypothesis and restrict right handed couplings of the #tau#. On the other hand, left handed scalar and tensor couplings of the #tau# channot be bounded in the model independent framework with presently available data. (orig.)23 refs.Available from TIB Hannover: RA 2999(95-188) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Hadronic vacuum polarization contribution to g - 2 of the leptons and #alpha#(M_Z)

We review and compare recent calculations of hadronic vacuum polarization effects. In particular, we consider the anomalous magnetic moments g-2 of the leptons and #alpha#(M_Z), the effective fine structure constant at the Z-resonance. (orig.)36 refs.Available from TIB Hannover: RA 2999(96-121) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Deep inelastic physics with H1

A summary is presented of deep inelastic physics results obtained by the H1 collaboration during its first three years of experimentation at the electron-proton collider HERA. (orig.)73 refs.Available from TIB Hannover: RA 2999(96-218) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Higgs boson searches at LEP

SIGLEAvailable from TIB Hannover: RA 2999(97-129) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Possible measurements of single and double spin asymmetries with HERA -#vector#N

The physics scope of a possible future experiment utilizing an internal polarized nucleon target in the HERA proton beam is discussed. By measuring single spin asymmetries in inclusive particle production at 820 GeV beam energy the higher-twist sector of perturbative QCD can be probed with good statistical sensitivity. To support the physics case for proton polarization at HERA, we consider the measurement of double spin asymmetries in photon plus jet production. It appears possible to determine the polarized gluon distribution in the range 0.1#<=#x_g_l_u_o_n#<=#0.4 with good accuracy. (orig.)24 refs.Available from TIB Hannover: RA 2999(96-095) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Non-perturbative renormalization of QCD

In these lectures, we discuss different types of renormalization problems in QCD and their non-perturbative solution in the framework of the lattice formulation. In particular the recursive finite size methods to compute the scale-dependence of renormalized quantities is explained. An important ingredient in the practical applications is the Schroedinger functional. It is introduced and its renormalization properties are discussed. Concerning applications, the computation of the running coupling and the running quark mass are covered in detail and it is shown how the #LAMBDA#-parameter and renormalization group invariant quark mass can be obtained. Further topics are the renormalization of isovector currents and non-perturbative Symanzik improvement. (orig.)Available from TIB Hannover: RA 2999(97-207) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Cosmological string solutions in 4 dimensions from 5d black holes

We obtain cosmological four dimensional solutions of the low energy effective string theory by reducing a five dimensional black hole, and black hole-de Sitter solution of Einstein gravity down to four dimensions. The appearance of a cosmological constant in the five dimensional Einstein-Hilbert action produces a special dilaton potential in the four dimensional effective string action. Cosmological scenarios implemented by our solutions are discussed. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(93-118) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

The Z boson resonance and radiative corrections

The Z line shape is measured at LEP with an accuracy at the per mille level. Usually it is described in the standard model of electroweak interactions with account of quantum corrections. Alternatively, one may attempt different model-independent approaches in order to extract quantities like mass and width of the Z boson. If a fit deviates from that in the standard approach, this may give hints for new physics contributions. I describe two model-independent approaches and compare their applications to LEP data with the standard model approach. (orig.)Available from TIB Hannover: RA 2999(97-218) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Connection between Feynman integrals having different values of the space-time dimension

A systematic algorithm for obtaining recurrence relations for dimensionally regularized Feynman integrals w.r.t. the space-time dimension d is proposed. The relation between d and d-2 dimensional integrals is given in terms of a differential operator for which an explicit formula can be obtained for each Feynman diagram. We show how the method works for one-, two- and three-loop integrals. The new recurrence relations w.r.t. d are complementary to the recurrence relations which derive from the method of integration by parts. We find that the problem of the irreducible numerators in Feynman integrals can be naturally solved in the framework of the proposed generalized recurrence relations. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(96-068) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

A new approach to the momentum expansion of multiloop Feynman diagrams

We present a new method for the momentum expansion of Feynman integrals with arbitrary masses and any number of loops and external momenta. By using the parametric representation we derive a generating function for the coefficients of the small momentum expansion of an arbitrary diagram. The method is applicable for the expansion w.r.t. all or a subset of external momenta. The coefficients of the expansion are obtained by applying a differential operator to a given integral with shifted value of the space-time dimension d and the expansion momenta set equal to zero. Integrals with changed d are evaluated by using the generalized recurrence relations proposed. We show how the method works for one- and two-loop integrals. It is also illustrated that our method is simpler and more efficient than others. (orig.)26 refs.Available from TIB Hannover: 2999(96-099) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman