Identification of b-quark jets with the CMS experiment
Austrian Federal Ministry of Science and Research ; Belgium Fonds de la Recherche Scientifique ; Fonds voor Wetenschappelijk Onderzoek ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; Bulgarian Ministry of Education and Science ; CERN ; Chinese Academy of Sciences ; Ministry of Science and Technology ; National Natural Science Foundation of China ; Colombian Funding Agency (COLCIENCIAS) ; Croatian Ministry of Science, Education and Sport ; Research Promotion Foundation, Cyprus ; Ministry of Education and Research ; European Regional Development Fund, Estonia ; Academy of Finland ; Finnish Ministry of Education and Culture ; Helsinki Institute of Physics ; Institut National de Physique Nucleaire et de Physique des Particules / CNRS, France ; Commissariat a l' Energie Atomique et aux Energies Alternatives / CEA, France ; Bundesministerium fur Bildung und Forschung, Germany ; Deutsche Forschungsgemeinschaft, Germany ; Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany ; General Secretariat for Research and Technology, Greece ; National Scientific Research Foundation ; National Office for Research and Technology, Hungary ; Department of Atomic Energy and the Department of Science and Technology, India ; Institute for Studies in Theoretical Physics and Mathematics, Iran ; Science Foundation, Ireland ; Istituto Nazionale di Fisica Nucleare, Italy ; Korean Ministry of Education, Science and Technology, India ; World Class University program of NRF, Korea ; Lithuanian Academy of Sciences ; CINVESTAV ; CONACYT ; SEP ; UASLP-FAI ; Ministry of Science and Innovation, New Zealand ; Pakistan Atomic Energy Commission ; Ministry of Science and Higher Education ; National Science Centre, Poland ; Fundacao para a Ciencia e a Tecnologia, Portugal ; JINR (Armenia) ; JINR (Belarus) ; JINR (Georgia) ; JINR (Ukraine) ; JINR (Uzbekistan) ; Ministry of Education and Science of the Russian Federation ; Federal Agency of Atomic Energy of the Russian Federation ; Russian Academy of Sciences ; Russian Foundation for Basic Research ; Ministry of Science and Technological Development of Serbia ; Secretaria de Estado de Investigacion, Desarrollo e Innovacion, Spain ; Programa Consolider-Ingenio, Spain ; ETH Board ; ETH Zurich ; PSI ; SNF ; UniZH ; Canton Zurich ; SER ; National Science Council, Taipei ; Scientific and Technical Research Council of Turkey ; Turkish Atomic Energy Authority ; Science and Technology Facilities Council, UK ; US Department of Energy ; US National Science Foundation ; Marie-Curie programme ; European Research Council (European Union) ; Leventis Foundation ; A. P. Sloan Foundation ; Alexander von Humboldt Foundation ; Austrian Science Fund (FWF) ; Belgian Federal Science Policy Office ; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium) ; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium) ; Council of Science and Industrial Research, India ; Compagnia di San Paolo (Torino) ; Foundation for Polish Science ; European Union ; Ministry of Education and ResearchSF0690030s09 ; At the Large Hadron Collider, the identification of jets originating from b quarks is important for searches for new physics and for measurements of standard model processes. A variety of algorithms has been developed by CMS to select b-quark jets based on variables such as the impact parameters of charged-particle tracks, the properties of reconstructed decay vertices, and the presence or absence of a lepton, or combinations thereof. The performance of these algorithms has been measured using data from proton-proton collisions at the LHC and compared with expectations based on simulation. The data used in this study were recorded in 2011 at root s = 7TeV for a total integrated luminosity of 5.0 fb(-1). The efficiency for tagging b-quark jets has been measured in events from multijet and t-quark pair production. CMS has achieved a b-jet tagging efficiency of 85% for a light-parton misidentification probability of 10% in multijet events. For analyses requiring higher purity, a misidentification probability of only 1.5% has been achieved, for a 70% b-jet tagging efficiency.