Predictions for Anomalous tau+ tau- gamma Production at LEP 1

We calculate distributions for tau+ tau- gamma production at LEP 1 taking into account a potentially existing anomalous magnetic moment a_tau of the tau lepton. The existing upper limits for |a_tau| are known from the dependence of the decay Z -> tau+ tau- gamma on (a_tau)^2 and are of the order of (1 - 5)%. We show that such limits are also sensitive to linear terms in a_tau, which are of equal importance at |a_tau| ~ (1 - 2)% and dominate below this value. Contributions from an electric dipole moment d_tau do not interfere with the electromagnetic vertex or with the anomalous magnetic moment. Appropriate formulae are derived.Comment: 13 pages, LaTex, 5 figure

MBsums - a Mathematica package for the representation of Mellin-Barnes integrals by multiple sums

Feynman integrals may be represented by the Mathematica packages AMBRE and MB as multiple Mellin-Barnes integrals. With the Mathematica package MBsums these Mellin-Barnes integrals are transformed into multiple sums.Comment: Part of a talk presented by J. Gluza at the XXXIX International Conference of Theoretical Physics "Matter to the Deepest", Ustron, Poland, September 13-18, 2015. Extended version of the contribution to the proceedings in Acta Physica Polonica 46 (2015

Massive Feynman integrals and electroweak corrections

There are steady advances in the calculation of electroweak corrections to massive scattering problems at colliders, from the very beginning in the nineteen seventies until contemporary developments. Recent years brought a remarkable progress due to new calculational technologies. This was motivated by demands from phenomenological applications at particle accelerators: higher multiplicities of the final states, extreme kinematics, need of higher precision and thus of higher orders in perturbation theory. We describe selected contributions from the project "Massive particle production" of Sonderforschungsbereich/Transregio 9 of Deutsche Forschungsgemeinschaft.Comment: Material presented at the final Workshop of Sonderforschungsbereich Transregio 9 "Advances in Computational Physics" of Deutsche Forschungsgemeinschaft (DFG), 15-19 Sep 2014, Durbach, Germany, to appear in the proceedings, 16 pages, 16 figures, 3 tables; references added in v

Off-shell W pair production with anomalous couplings: The CC11 process

The differential cross-sections for processes of the type e+ e- to W+ W- to l nu q anti-q are determined with account of background contributions and of anomalous triple gauge boson couplings. Analytic expressions for dsigma/ds1 ds2 dcostheta, where theta is the production angle of the W boson, are numerically integrated with the Fortran package GENTLE. QED corrections are taken into account in the leading logarithmic approximation. The importance of the various contributions is studied for center-of-mass energies of 190 GeV, 500 GeV, and 1 TeV.Comment: 26 pages, Latex, 6 figures, 2 tables, uses feynmp and epsf styles; tables numerically updated, 5 references added, few typos corrected, version to be published in EPJ

Scalar 1-loop Feynman integrals as meromorphic functions in space-time dimension d

The long-standing problem of representing the general massive one-loop Feynman integral as a meromorphic function of the space-time dimension $d$ has been solved for the basis of scalar one- to four-point functions with indices one. In 2003 the solution of difference equations in the space-time dimension allowed to determine the necessary classes of special functions: self-energies need ordinary logarithms and Gauss hypergeometric functions $_2F_1$, vertices need additionally Kamp\'{e} de F\'{e}riet-Appell functions $F_1$, and box integrals also Lauricella-Saran functions $F_S$. In this study, alternative recursive Mellin-Barnes representations are used for the representation of $n$-point functions in terms of $(n-1)$-point functions. The approach enabled the first derivation of explicit solutions for the Feynman integrals at arbitrary kinematics. In this article, we scetch our new representations for the general massive vertex and box Feynman integrals and derive a numerical approach for the necessary Appell functions $F_1$ and Saran functions $F_S$ at arbitrary kinematical arguments.Comment: 9 pages, 3 table

The line shape of the ZZ boson

At LEP~1, cross sections and cross section asymmetries may be analysed model independently. Cross sections depend on four, asymmetries on two free parameters. As an example, I discuss the model independent $Z$ boson mass determination from the $Z$ line shape and compare it to the Standard Model approach.Comment: 7 pages (LaTeX), 1 figure (not included); a uuencoded file containing the LaTeX and all postscript files is available via anonymous ftp at ftp://ftp.ifh.de/pub/preprint/desy94-253.u