arXiv subjects
Publications and source records attributed to K. Rabbertz.
We present a method for very fast repeated computations of higher-order cross sections in hadron-induced processes for arbitrary parton density functions. A full implementation of the method for computations of jet cross sections in Deep-Inelastic Scattering and in Hadron-Hadron Collisions is offered by the "fastNLO" project. A web-interface for online calculations and user code can be found at http://hepforge.cedar.ac.uk/fastnlo/ .
The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse femtobarn of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focussed on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.
The efficient exploitation of worldwide distributed storage and computing resources available in the grids require a robust, transparent and fast deployment of experiment specific software. The approach followed by the CMS experiment at CERN in order to enable Monte-Carlo simulations, data analysis and software development in an international collaboration is presented. The current status and future improvement plans are described.
PAX (Physics Analysis Expert) is a novel, C++ based toolkit designed to assist teams in particle physics data analysis issues. The core of PAX are event interpretation containers, holding relevant information about and possible interpretations of a physics event. Providing this new level of abstraction beyond the results of the detector reconstruction programs, PAX facilitates the buildup and use of modern analysis factories. Class structure and user command syntax of PAX are set up to support expert teams as well as newcomers in preparing for the challenges expected to arise in the data analysis at future hadron colliders.
From 1996 up to 2000 the LEP collider at CERN has operated at center of mass energies above the production threshold for W boson pairs of approximately 160 GeV. The obtained data are used to extract a preliminary W mass value of (80.450 +- 0.039) GeV by direct reconstruction. To a large extent the uncertainty is due to systematic effects especially in the fully hadronic decay channel W+W- --> qq' qq' that suffers most from ambiguities in modelling the hadronic final state. Methods to assess and reduce these uncertainties are the current main concern of the four LEP experiments.
Deep-inelastic ep scattering data, taken with the H1 and ZEUS detectors at HERA, are used to study the means and distributions of the event shape variables thrust, jet broadening, jet mass, C-parameter and two kinds of differential two-jet rate. The data cover a range of the four-momentum transfer Q, taken to be the relevant energy scale, between 7 GeV and 141 GeV. The Q dependences are compared with second-order calculations of perturbative QCD. Power law corrections are applied to account for hadronization effects.
Deep-inelastic ep scattering data, taken with the H1 detector at HERA, are used to study event shape variables over a large range of "relevant energy" Q between 7 GeV and 100 GeV. Previously published analysis on thrust, jet broadening, jet mass and C parameter are substantially refined and updated; differential two-jet rates treated as event shapes are presented for the first time. The Q dependence of the mean values is fit to second order calculations of perturbative QCD applying power law corrections proportional to 1/Q^p to account for hadronization effects. The concept of these power corrections is tested by a systematic investigation in terms of a non-perturbative parameter \bar{alpha}_{p-1} and the strong coupling constant.
Deep-inelastic ep scattering data, taken with the H1 detector at HERA, are used to study the event shape variables thrust, jet broadening, jet mass, C parameter, and two kinds of differential two-jet rates over a large range of ``relevant energy'' Q between 7 GeV and 100 GeV. The Q dependence of the mean values is fit to second order calculations of perturbative QCD applying power law corrections proportional to 1/Q^p to account for hadronization effects. The concept of these power corrections is tested by a systematic investigation in terms of a non-perturbative parameter alpha_{p-1} and the strong coupling constant.