Physics Analysis Expert PAX: First Applications

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.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX, 10 eps figures. PSN THLT00

Automated Reconstruction of Particle Cascades in High Energy Physics Experiments

We present a procedure for reconstructing particle cascades from event data measured in a high energy physics experiment. For evaluating the hypothesis of a specific physics process causing the observed data, all possible reconstruction versions of the scattering process are constructed from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.Comment: 8 pages, 2 figures. Submitted to Computational Science & Discover

The new object oriented analysis framework for H1

During the years 2000 and 2001 the HERA machine and the H1 experiment performed substantial luminosity upgrades. To cope with the increased demands on data handling an effort was made to redesign and modernize the analysis software. Main goals were to lower turn-around time for physics analysis by providing a single framework for data storage, event selection, physics and event display. The new object oriented analysis environment based on the RooT framework provides a data access front-end for the new data storage scheme and a new event display. The analysis data is stored in four different layers of separate files. Each layer represents a different level of abstraction, i.e. reconstruction output, physics particles, event summary information and user specific information. Links between the layers allow correlating quantities of different layers. Currently, this framework is used for data analyses of the previous collected data and for standard data production of the currently collected data.Comment: Talk from the 2003 Computing in High energy and Nuclear Physics (CHEP 03), La Jolla, Ca. USA, March 2003, 3 pages, 1 eps figure, PSN THLT 00

Search for heavy resonances decaying to top quarks

In many models of physics beyond the Standard Model the coupling of new states to third generation quarks is enhanced. A review is presented of searches by the CMS collaboration for heavy particles decaying to final states involving top quarks. This includes searches for heavy gauge bosons and excited states. Several final states originating from the top quark decays are considered and the event reconstruction is optimised accordingly. The analyses presented use data collected with the CMS experiment during the year 2012 at the LHC, in proton-proton collisions at a centre-of-mass energy of 8 TeV.Comment: Submitted to the proceedings of "The European Physical Society Conference on High Energy Physics - EPS-HEP2013", 18-24 July 2013, Stockholm, Sweden; 6 pages, 3 figure

The ATLAS Track Extrapolation Package

The extrapolation of track parameters and their associated covariances to destination surfaces of different types is a very frequent process in the event reconstruction of high energy physics experiments. This is amongst other reasons due to the fact that most track and vertex fitting techniques are based on the first and second momentum of the underlying probability density distribution. The correct stochastic or deterministic treatment of interactions with the traversed detector material is hereby crucial for high quality track reconstruction throughout the entire momentum range of final state particles that are produced in high energy physics collision experiments. This document presents the main concepts, the algorithms and the implementation of the newly developed, powerful ATLAS track extrapolation engine. It also emphasises on validation procedures, timing measurements and the integration into the ATLAS offline reconstruction software

Low energy event reconstruction in IceCube DeepCore

The reconstruction of event-level information, such as the direction or energy of a neutrino interacting in IceCube DeepCore, is a crucial ingredient to many physics analyses. Algorithms to extract this high level information from the detector’s raw data have been successfully developed and used for high energy events. In this work, we address unique challenges associated with the reconstruction of lower energy events in the range of a few to hundreds of GeV and present two separate, state-of-the-art algorithms. One algorithm focuses on the fast directional reconstruction of events based on unscattered light. The second algorithm is a likelihood-based multipurpose reconstruction offering superior resolutions, at the expense of larger computational cost