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No. of bitstreams: 0 Previous issue date: 2017-05-03 Austrian Federal Ministry of Science, Research and Economy Austrian Science Fund Belgian 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 Croatian Science Foundation Research Promotion Foundation, Cyprus Secretariat for Higher Education, Science, Technology and Innovation, Ecuador Ministry of Education and Research, Estonian Research Council 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 Commissariat a l'Energie Atomique et aux Energies Alternatives / CEA, France Bundesministerium fur Bildung and Forschung Deutsche Forschungsgemeinschaft Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany General Secretariat for Research and Technology, Greece National Scientific Research Foundation National Innovation Office, Hungary Department of Atomic Energy Department of Science and Technology, India Institute for Studies in Theoretical Physics and Mathematics, Iran Science Foundation, Ireland Istituto Nazionale di Fisica Nucleare, Italy Ministry of Science, ICT and Future Planning National Research Foundation (NRF), Republic of Korea Lithuanian Academy of Sciences Ministry of Education University of Malaya (Malaysia) BUAP CINVESTAV CONACYT LNS SEP UASLP-FAI Ministry of Business, Innovation and Employment, 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, Dubna 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 Education, Science and Technological Development of Serbia Secretaria de Estado de Investigacion, Desarrollo e Innovation and Programa Consolider-Ingenio, Spain ETH Board ETH Zurich PSI SNF UniZH Canton Zurich SER Ministry of Science and Technology, Taipei Thailand Center of Excellence in Physics Institute for the Promotion of Teaching Science and Technology of Thailand Special Task Force for Activating Research National Science and Technology Development Agency of Thailand Scientific and Technical Research Council of Turkey Turkish Atomic Energy Authority National Academy of Sciences of Ukraine State Fund for Fundamental Researches, Ukraine Science and Technology Facilities Council, UK US Department of Energy US National Science Foundation Marie-Curie program European Research Council EPLANET (European Union) Leventis Foundation A. P. Sloan Foundation Alexander von Humboldt Foundation 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) Ministry of Education, Youth and Sports (MEYS) of the Czech Republic Council of Science and Industrial Research, India HOMING PLUS program of the Foundation for Polish Science European Union Mobility Plus program of the Ministry of Science and Higher Education National Science Center (Poland) EU-ESF Greek NSRF National Priorities Research Program by Qatar National Research Fund Programa Clarin-COFUND del Principado de Asturias Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand) Welch Foundation Pair production of gamma(1S) mesons is observed at the LHC in proton-proton collisions at root s = 8 TeV by the CMS experiment in a data sample corresponding to an integrated luminosity of 20.7 fb(-1). Both gamma(1S) candidates are fully reconstructed via their decays to mu(+) mu(-). The fiducial acceptance region is defined by an absolute gamma(1S) rapidity smaller than 2.0. The fiducial cross section for the production of gamma(1S) pairs, assuming that both mesons decay isotropically, is measured to be 68.8 +/- 12.7 (stat) +/- 7.4 (syst) +/- 2.8 (B) pb, where the third uncertainty comes from the uncertainty in the branching fraction of gamma(1S) decays to mu(+) mu(-). Assuming instead that the gamma(1S) mesons are produced with different polarizations leads to variations in the measured cross section in the range from 38% to +36%. 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