Observation of long-range, near-side angular correlations in proton-proton collisions at the LHC

38 páginas, 10 figuras, 4 tablas.--  This article is distributed under the terms of the Creative Commons\ud
Attribution Noncommercial License which permits any noncommercial use, distribution,\ud
and reproduction in any medium, provided the original author(s) and source are credited.-- CMS Collaboration: et al.Results on two-particle angular correlations for charged particles emitted in proton-proton collisions at center-of-mass energies of 0.9, 2.36, and 7 TeV are presented, using data collected with the CMS detector over a broad range of pseudorapidity (η) and azimuthal angle (ϕ). Short-range correlations in Δη, which are studied in minimum bias events, are characterized using a simple “independent cluster” parametrization in order to quantify their strength (cluster size) and their extent in η (cluster decay width). Long-range azimuthal correlations are studied differentially as a function of charged particle multiplicity and particle transverse momentum using a 980 nb−1 data set at 7 TeV. In high multiplicity events, a pronounced structure emerges in the two-dimensional correlation function for particle pairs with intermediate p T of 1–3 GeV/c, 2.0 < |Δη| < 4.8 and Δϕ ≈ 0. This is the first observation of such a long-range, near-side feature in two-particle correlation functions in pp or p[`(p)]ppcollisions.We thank the technical and administrative sta  at CERN and other CMS institutes. This\ud
work was supported by the Austrian Federal Ministry of Science and Research; the Belgium\ud
Fonds de la Recherche Scienti que, and Fonds voor Wetenschappelijk Onderzoek;\ud
the Brazilian Funding Agencies (CNPq, CAPES, FAPERJ, and FAPESP); the Bulgarian\ud
Ministry of Education and Science; CERN; the Chinese Academy of Sciences, Ministry of\ud
Science and Technology, and National Natural Science Foundation of China; the Colombian\ud
Funding Agency (COLCIENCIAS); the Croatian Ministry of Science, Education and\ud
Sport; the Research Promotion Foundation, Cyprus; the Estonian Academy of Sciences\ud
and NICPB; the Academy of Finland, Finnish Ministry of Education, and Helsinki Institute\ud
of Physics; the Institut National de Physique Nucl eaire et de Physique des Particules\ud
/ CNRS, and Commissariat  a l' Energie Atomique, France; the Bundesministerium f ur\ud
Bildung und Forschung, Deutsche Forschungsgemeinschaft, and Helmholtz-Gemeinschaft\ud
Deutscher Forschungszentren, Germany; the General Secretariat for Research and Technology,\ud
Greece; the National Scienti c Research Foundation, and National O ce for Research\ud
and Technology, Hungary; the Department of Atomic Energy, and Department of Science\ud
and Technology, India; the Institute for Studies in Theoretical Physics and Mathematics,\ud
Iran; the Science Foundation, Ireland; the Istituto Nazionale di Fisica Nucleare, Italy;\ud
the Korean Ministry of Education, Science and Technology and the World Class University\ud
program of NRF, Korea; the Lithuanian Academy of Sciences; the Mexican Funding\ud
Agencies (CINVESTAV, CONACYT, SEP, and UASLP-FAI); the Pakistan Atomic Energy\ud
Commission; the State Commission for Scienti c Research, Poland; the Funda c~ao para a\ud
Ci^encia e a Tecnologia, Portugal; JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan);\ud
the Ministry of Science and Technologies of the Russian Federation, and Russian Ministry\ud
of Atomic Energy; the Ministry of Science and Technological Development of Serbia; the\ud
Ministerio de Ciencia e Innovaci on, and Programa Consolider-Ingenio 2010, Spain; the\ud
Swiss Funding Agencies (ETH Board, ETH Zurich, PSI, SNF, UniZH, Canton Zurich, and\ud
SER); the National Science Council, Taipei; the Scienti c and Technical Research Council\ud
of Turkey, and Turkish Atomic Energy Authority; the Science and Technology Facilities\ud
Council, UK; the US Department of Energy, and the US National Science Foundation.\ud
Individuals have received support from the Marie-Curie IEF program (European Union);\ud
the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation;\ud
and the Associazione per lo Sviluppo Scienti co e Tecnologico del Piemonte (Italy).Peer reviewe