Computing and Informatics

A preliminary combination of Standard Model Higgs searches with the ATLAS experiment, in a dataset collected at energy sqrts = 7 TeV at the LHC in year 2011, is presented. footnoteThe paper refers to the status of Higgs boson searches as from March 2012, before the Higgs discovery at LHC. The Higgs boson mass ranges from 112.7 GeV to 115.5 GeV, 131 GeV to 237 GeV and 251 GeV to 468 GeV are excluded at the 95 % confidence level. An excess of events is observed for a Higgs boson mass hypothesis close to 126 GeV. This successful analysis was possible due to the excellent performance of the GRID distributed computing system, in which two Polish sites ACK Cyfronet from Krakow and PSNC from Poznan have participated. The ATLAS analysis chain and the usage of grid for ATLAS data processing are described in this paper.