On the difference between FOPT and CIPT for hadronic tau decays.

In this article we review the results of our recent work on the difference between the Borel representations of hadronic spectral function moments obtained with the CIPT and FOPT methods. For the presentation of the theoretical results we focus on the large- approximation, where all expressions can be written down in closed form, and we comment on the generalization to full QCD. The results may explain the discrepancy in the behavior of the FOPT and CIPT series that has been the topic of intense discussions in previous literature and which represents a major part of the theoretical uncertainties in current strong coupling determinations from hadronic decays.

Top Quark Mass Calibration for Monte Carlo Event Generators.

The most precise top quark mass measurements use kinematic reconstruction methods, determining the top mass parameter of a Monte Carlo event generator m_{t}^{MC}. Because of hadronization and parton-shower dynamics, relating m_{t}^{MC} to a field theory mass is difficult. We present a calibration procedure to determine this relation using hadron level QCD predictions for observables with kinematic mass sensitivity.

Infrared renormalization-group flow for heavy-quark masses.

A short-distance heavy-quark mass depends on two parameters: the renormalization scale mu and a scale R controlling the absorption of infrared fluctuations. The radius for perturbative corrections that build up the mass beyond its pointlike definition in the pole scheme is approximately 1/R. Treating R as a variable gives a renormalization-group equation.