Final Activity Report Summary - ALGOTOOS (Algorithms and tools for multi-particle production and higher order corrections at high energy colliders) The ALGOTOOLS project was designed to contribute to the intensive phenomenological studies that were needed to investigate particle physics at present and future high-energy colliders. The latter are expected to provide a major step in the understanding of the ultimate building blocks of matter and their interactions. This fundamental knowledge might have far-reaching consequences for technology development in the 21st century in much the same way as the development of quantum mechanics influenced everyday life in the 20th century. Elementary particle physics aims to describe the fundamental constituents of nature. The large scale international accelerator experiments in Europe, namely the ongoing large hadron collider (LHC) at the European Centre for Nuclear Research (CERN) and the planned linear collider (LC) project, will provide us with new insights in the world of elementary particles. The high energy and high luminosity available at the future colliders will allow for the study of scattering processes with very high accuracy and, in particular, for the study of hard processes with many particles involved. In order to meet the high precision requirements, reliable theoretical predictions as well as the development of the relevant computational tools to be used as the basic ingredients of the experimental simulation programmes, are indispensable. Moreover, direct 'new physics' effects manifest themselves into multi-particle final states and, therefore, their investigation relies on the detailed knowledge of both the standard model, i.e. the currently best known description of particle physics, background as well as the new physics contributions to multi-particle production. The work performed during the course of ALGOTOOLS had a very significant impact on the current knowledge by developing new algorithms and tools that would allow for the accurate theoretical description of multi-particle processes at high energies. The main objectives achieved by the project were: 1. the development of innovative methods and algorithms for multi-particle production based on Dyson-Schwinger recursive equations. The Helac-Phegas tool was further developed and a user-friendly version started to be implemented within the software framework of the large experimental groups, ATLAS and CMS (LHC) 2. the investigation of direct numerical approaches to Feynman integrals, which, in combination with the Dyson-Schwinger recursive equations, provided an efficient way to compute higher order corrections to multi-particle processes. The novel method developed by Ossola, Papadopoulos and Pittau, all participating in ALGOTOOLS, and known under the name of OPP-method, was a breakthrough in the field of one loop calculations. New tools as Helac-1L and Helac-Dipoles were developed and allowed for the calculation of NLO corrections for physics at the LHC 3. the implementation of new physics effects, particularly for the minimal supersymmetric standard model and the study of theories beyond the standard model. The transfer of knowledge and training activities of the project were structured and balanced between incoming and outgoing experienced researchers. Partner teams from leading European institutes and international organisations were participating, offering high-quality specialised training to the staff members of the host organisation. The successful completion of the project had a very important impact on the future research activity of the group, by providing the necessary expertise to deal with the complicated physics problems and the anticipated level of precision demanded by the forthcoming accelerator experiments. It further established the position of the group within the particle physics community in Europe and facilitated its involvement in European research networks and international collaborations.
