https://doi.org/10.1140/epjc/s10052-016-4126-5
Regular Article - Experimental Physics
Measurement of the charged-particle multiplicity inside jets from 
pp collisions with the ATLAS detector
1
Department of Physics, University of Adelaide, Adelaide, Australia
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Physics Department, SUNY Albany, Albany, NY, USA
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Department of Physics, University of Alberta, Edmonton, AB, Canada
4
Department of Physics, Ankara University, Ankara, Turkey
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Istanbul Aydin University, Istanbul, Turkey
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Division of Physics, TOBB University of Economics and Technology, Ankara, Turkey
7
LAPP, CNRS/IN2P3 and Université Savoie Mont Blanc, Annecy-le-Vieux, France
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High Energy Physics Division, Argonne National Laboratory, Argonne, IL, USA
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Department of Physics, University of Arizona, Tucson, AZ, USA
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Department of Physics, The University of Texas at Arlington, Arlington, TX, USA
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Physics Department, University of Athens, Athens, Greece
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Physics Department, National Technical University of Athens, Zografou, Greece
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Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan
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Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Barcelona, Spain
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Institute of Physics, University of Belgrade, Belgrade, Serbia
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Department for Physics and Technology, University of Bergen, Bergen, Norway
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Physics Division, Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, USA
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Department of Physics, Humboldt University, Berlin, Germany
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Albert Einstein Center for Fundamental Physics and Laboratory for High Energy Physics, University of Bern, Bern, Switzerland
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School of Physics and Astronomy, University of Birmingham, Birmingham, UK
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Department of Physics, Bogazici University, Istanbul, Turkey
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Department of Physics Engineering, Gaziantep University, Gaziantep, Turkey
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Faculty of Engineering and Natural Sciences, Istanbul Bilgi University, Istanbul, Turkey
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Faculty of Engineering and Natural Sciences, Bahcesehir University, Istanbul, Turkey
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Centro de Investigaciones, Universidad Antonio Narino, Bogota, Colombia
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INFN Sezione di Bologna, Bologna, Italy
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Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna, Italy
28
Physikalisches Institut, University of Bonn, Bonn, Germany
29
Department of Physics, Boston University, Boston, MA, USA
30
Department of Physics, Brandeis University, Waltham, MA, USA
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Universidade Federal do Rio De Janeiro COPPE/EE/IF, Rio de Janeiro, Brazil
32
Electrical Circuits Department, Federal University of Juiz de Fora (UFJF), Juiz de Fora, Brazil
33
Federal University of Sao Joao del Rei (UFSJ), Sao Joao del Rei, Brazil
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Instituto de Fisica, Universidade de Sao Paulo, São Paulo, Brazil
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Physics Department, Brookhaven National Laboratory, Upton, NY, USA
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Transilvania University of Brasov, Brasov, Romania
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National Institute of Physics and Nuclear Engineering, Bucharest, Romania
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Physics Department, National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca, Romania
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University Politehnica Bucharest, Bucharest, Romania
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West University in Timisoara, Timisoara, Romania
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Departamento de Física, Universidad de Buenos Aires, Buenos Aires, Argentina
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Cavendish Laboratory, University of Cambridge, Cambridge, UK
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Department of Physics, Carleton University, Ottawa, ON, Canada
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CERN, Geneva, Switzerland
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Enrico Fermi Institute, University of Chicago, Chicago, IL, USA
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Departamento de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
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Departamento de Física, Universidad Técnica Federico Santa María, Valparaiso, Chile
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Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
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Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui, China
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Department of Physics, Nanjing University, Nanjing, Jiangsu, China
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School of Physics, Shandong University, Jinan, Shandong, China
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Shanghai Key Laboratory for Particle Physics and Cosmology, Department of Physics and Astronomy, Shanghai Jiao Tong University, also affiliated with PKU-CHEP, Shanghai, China
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Physics Department, Tsinghua University, Beijing, 100084, China
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Laboratoire de Physique Corpusculaire, Clermont Université and Université Blaise Pascal and CNRS/IN2P3, Clermont-Ferrand, France
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Nevis Laboratory, Columbia University, Irvington, NY, USA
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Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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INFN Gruppo Collegato di Cosenza, Laboratori Nazionali di Frascati, Frascati, Italy
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Dipartimento di Fisica, Università della Calabria, Rende, Italy
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Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
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Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
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Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
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Physics Department, Southern Methodist University, Dallas, TX, USA
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Physics Department, University of Texas at Dallas, Richardson, TX, USA
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DESY, Hamburg and Zeuthen, Germany
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Institut für Experimentelle Physik IV, Technische Universität Dortmund, Dortmund, Germany
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Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden, Germany
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Department of Physics, Duke University, Durham, NC, USA
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SUPA-School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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INFN Laboratori Nazionali di Frascati, Frascati, Italy
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Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg, Germany
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Section de Physique, Université de Genève, Geneva, Switzerland
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INFN Sezione di Genova, Genoa, Italy
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Dipartimento di Fisica, Università di Genova, Genoa, Italy
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E. Andronikashvili Institute of Physics, Iv. Javakhishvili Tbilisi State University, Tbilisi, Georgia
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High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia
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II Physikalisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany
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SUPA-School of Physics and Astronomy, University of Glasgow, Glasgow, UK
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II Physikalisches Institut, Georg-August-Universität, Göttingen, Germany
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Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3, Grenoble, France
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Department of Physics, Hampton University, Hampton, VA, USA
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Laboratory for Particle Physics and Cosmology, Harvard University, Cambridge, MA, USA
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Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
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Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
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ZITI Institut für technische Informatik, Ruprecht-Karls-Universität Heidelberg, Mannheim, Germany
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Faculty of Applied Information Science, Hiroshima Institute of Technology, Hiroshima, Japan
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Department of Physics, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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Department of Physics, The University of Hong Kong, Hong Kong, China
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Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
89
Department of Physics, Indiana University, Bloomington, IN, USA
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Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität, Innsbruck, Austria
91
University of Iowa, Iowa City, IA, USA
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Department of Physics and Astronomy, Iowa State University, Ames, IA, USA
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Department of Physics and Astronomy, University of California Irvine, Irvine, CA, USA
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Joint Institute for Nuclear Research, JINR Dubna, Dubna, Russia
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KEK, High Energy Accelerator Research Organization, Tsukuba, Japan
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Graduate School of Science, Kobe University, Kobe, Japan
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Faculty of Science, Kyoto University, Kyoto, Japan
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Kyoto University of Education, Kyoto, Japan
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Department of Physics, Kyushu University, Fukuoka, Japan
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Instituto de Física La Plata, Universidad Nacional de La Plata and CONICET, La Plata, Argentina
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Physics Department, Lancaster University, Lancaster, UK
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INFN Sezione di Lecce, Lecce, Italy
103
Dipartimento di Matematica e Fisica, Università del Salento, Lecce, Italy
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Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK
105
Department of Physics, Jožef Stefan Institute and University of Ljubljana, Ljubljana, Slovenia
106
School of Physics and Astronomy, Queen Mary University of London, London, UK
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Department of Physics, Royal Holloway University of London, Surrey, UK
108
Department of Physics and Astronomy, University College London, London, UK
109
Louisiana Tech University, Ruston, LA, USA
110
Laboratoire de Physique Nucléaire et de Hautes Energies, UPMC and Université Paris-Diderot and CNRS/IN2P3, Paris, France
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Fysiska institutionen, Lunds universitet, Lund, Sweden
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Departamento de Fisica Teorica C-15, Universidad Autonoma de Madrid, Madrid, Spain
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Institut für Physik, Universität Mainz, Mainz, Germany
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School of Physics and Astronomy, University of Manchester, Manchester, UK
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CPPM, Aix-Marseille Université and CNRS/IN2P3, Marseille, France
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Department of Physics, University of Massachusetts, Amherst, MA, USA
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Department of Physics, McGill University, Montreal, QC, Canada
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School of Physics, University of Melbourne, Melbourne, VIC, Australia
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Department of Physics, The University of Michigan, Ann Arbor, MI, USA
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Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
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INFN Sezione di Milano, Milan, Italy
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Dipartimento di Fisica, Università di Milano, Milan, Italy
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B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk, Republic of Belarus
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National Scientific and Educational Centre for Particle and High Energy Physics, Minsk, Republic of Belarus
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Group of Particle Physics, University of Montreal, Montreal, QC, Canada
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P.N. Lebedev Physical Institute of the Russian, Academy of Sciences, Moscow, Russia
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Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia
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National Research Nuclear University MEPhI, Moscow, Russia
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D.V. Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow, Russia
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Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
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Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Munich, Germany
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Nagasaki Institute of Applied Science, Nagasaki, Japan
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Graduate School of Science and Kobayashi-Maskawa Institute, Nagoya University, Nagoya, Japan
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INFN Sezione di Napoli, Naples, Italy
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Dipartimento di Fisica, Università di Napoli, Naples, Italy
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Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA
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Institute for Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen/Nikhef, Nijmegen, The Netherlands
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Nikhef National Institute for Subatomic Physics and University of Amsterdam, Amsterdam, The Netherlands
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Department of Physics, Northern Illinois University, DeKalb, IL, USA
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Budker Institute of Nuclear Physics, SB RAS, Novosibirsk, Russia
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Department of Physics, New York University, New York, NY, USA
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Ohio State University, Columbus, OH, USA
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Faculty of Science, Okayama University, Okayama, Japan
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Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK, USA
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Department of Physics, Oklahoma State University, Stillwater, OK, USA
146
Palacký University, RCPTM, Olomouc, Czech Republic
147
Center for High Energy Physics, University of Oregon, Eugene, OR, USA
148
LAL, Univ. Paris-Sud, CNRS/IN2P3, Université Paris Saclay, Orsay, France
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Graduate School of Science, Osaka University, Osaka, Japan
150
Department of Physics, University of Oslo, Oslo, Norway
151
Department of Physics, Oxford University, Oxford, UK
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INFN Sezione di Pavia, Pavia, Italy
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Dipartimento di Fisica, Università di Pavia, Pavia, Italy
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Department of Physics, University of Pennsylvania, Philadelphia, PA, USA
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National Research Centre “Kurchatov Institute” B.P.Konstantinov Petersburg Nuclear Physics Institute, St. Petersburg, Russia
156
INFN Sezione di Pisa, Pisa, Italy
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Dipartimento di Fisica E. Fermi, Università di Pisa, Pisa, Italy
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Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA
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Laboratório de Instrumentação e Física Experimental de Partículas-LIP, Lisbon, Portugal
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Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
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Department of Physics, University of Coimbra, Coimbra, Portugal
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Centro de Física Nuclear da Universidade de Lisboa, Lisbon, Portugal
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Departamento de Fisica, Universidade do Minho, Braga, Portugal
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Departamento de Fisica Teorica y del Cosmos and CAFPE, Universidad de Granada, Granada, Spain
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Dep Fisica and CEFITEC of Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
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Institute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic
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Czech Technical University in Prague, Praha, Czech Republic
168
Faculty of Mathematics and Physics, Charles University in Prague, Praha, Czech Republic
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State Research Center Institute for High Energy Physics, (Protvino), NRC KI, Protvino, Russia
170
Particle Physics Department, Rutherford Appleton Laboratory, Didcot, UK
171
INFN Sezione di Roma, Rome, Italy
172
Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy
173
INFN Sezione di Roma Tor Vergata, Rome, Italy
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Dipartimento di Fisica, Università di Roma Tor Vergata, Rome, Italy
175
INFN Sezione di Roma Tre, Rome, Italy
176
Dipartimento di Matematica e Fisica, Università Roma Tre, Rome, Italy
177
Faculté des Sciences Ain Chock, Réseau Universitaire de Physique des Hautes Energies-Université Hassan II, Casablanca, Morocco
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Centre National de l’Energie des Sciences Techniques Nucleaires, Rabat, Morocco
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Faculté des Sciences Semlalia, Université Cadi Ayyad, LPHEA-Marrakech, Marrakech, Morocco
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Faculté des Sciences, Université Mohamed Premier and LPTPM, Oujda, Morocco
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Faculté des Sciences, Université Mohammed V, Rabat, Morocco
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DSM/IRFU (Institut de Recherches sur les Lois Fondamentales de l’Univers), CEA Saclay (Commissariat à l’Energie Atomique et aux Energies Alternatives), Gif-sur-Yvette, France
183
Santa Cruz Institute for Particle Physics, University of California Santa Cruz, Santa Cruz, CA, USA
184
Department of Physics, University of Washington, Seattle, WA, USA
185
Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
186
Department of Physics, Shinshu University, Nagano, Japan
187
Fachbereich Physik, Universität Siegen, Siegen, Germany
188
Department of Physics, Simon Fraser University, Burnaby, BC, Canada
189
SLAC National Accelerator Laboratory, Stanford, CA, USA
190
Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovak Republic
191
Department of Subnuclear Physics, Institute of Experimental Physics of the Slovak Academy of Sciences, Kosice, Slovak Republic
192
Department of Physics, University of Cape Town, Cape Town, South Africa
193
Department of Physics, University of Johannesburg, Johannesburg, South Africa
194
School of Physics, University of the Witwatersrand, Johannesburg, South Africa
195
Department of Physics, Stockholm University, Stockholm, Sweden
196
The Oskar Klein Centre, Stockholm, Sweden
197
Physics Department, Royal Institute of Technology, Stockholm, Sweden
198
Departments of Physics and Astronomy and Chemistry, Stony Brook University, Stony Brook, NY, USA
199
Department of Physics and Astronomy, University of Sussex, Brighton, UK
200
School of Physics, University of Sydney, Sydney, Australia
201
Institute of Physics, Academia Sinica, Taipei, Taiwan
202
Department of Physics, Technion: Israel Institute of Technology, Haifa, Israel
203
Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
204
Department of Physics, Aristotle University of Thessaloniki, Thessaloníki, Greece
205
International Center for Elementary Particle Physics and Department of Physics, The University of Tokyo, Tokyo, Japan
206
Graduate School of Science and Technology, Tokyo Metropolitan University, Tokyo, Japan
207
Department of Physics, Tokyo Institute of Technology, Tokyo, Japan
208
Department of Physics, University of Toronto, Toronto, ON, Canada
209
TRIUMF, Vancouver, BC, Canada
210
Department of Physics and Astronomy, York University, Toronto, ON, Canada
211
Faculty of Pure and Applied Sciences, and Center for Integrated Research in Fundamental Science and Engineering, University of Tsukuba, Tsukuba, Japan
212
Department of Physics and Astronomy, Tufts University, Medford, MA, USA
213
INFN Gruppo Collegato di Udine, Sezione di Trieste, Udine, Italy
214
ICTP, Trieste, Italy
215
Dipartimento di Chimica Fisica e Ambiente, Università di Udine, Udine, Italy
216
Department of Physics and Astronomy, University of Uppsala, Uppsala, Sweden
217
Department of Physics, University of Illinois, Urbana, IL, USA
218
Instituto de Física Corpuscular (IFIC) and Departamento de Física Atómica, Molecular y Nuclear and Departamento de Ingeniería Electrónica and Instituto de Microelectrónica de Barcelona (IMB-CNM), University of Valencia and CSIC, Valencia, Spain
219
Department of Physics, University of British Columbia, Vancouver, BC, Canada
220
Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada
221
Department of Physics, University of Warwick, Coventry, UK
222
Waseda University, Tokyo, Japan
223
Department of Particle Physics, The Weizmann Institute of Science, Rehovot, Israel
224
Department of Physics, University of Wisconsin, Madison, WI, USA
225
Fakultät für Physik und Astronomie, Julius-Maximilians-Universität, Würzburg, Germany
226
Fakultät für Mathematik und Naturwissenschaften, Fachgruppe Physik, Bergische Universität Wuppertal, Wuppertal, Germany
227
Department of Physics, Yale University, New Haven, CT, USA
228
Yerevan Physics Institute, Yerevan, Armenia
229
Centre de Calcul de l’Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), Villeurbanne, France
230
CERN, Geneva, Switzerland
* e-mail: atlas.publications@cern.ch
Received:
3
February
2016
Accepted:
4
May
2016
Published online:
13
June
2016
The number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-perturbative components of fragmentation. This paper presents a measurement of the average number of charged particles with 
inside high-momentum jets in dijet events using 20.3 fb
of data recorded with the ATLAS detector in pp collisions at collisions at the LHC. The jets considered have transverse momenta from 50 
up to and beyond 1.5 . The reconstructed charged-particle track multiplicity distribution is unfolded to remove distortions from detector effects and the resulting charged-particle multiplicity is compared to several models. Furthermore, quark and gluon jet fractions are used to extract the average charged-particle multiplicity for quark and gluon jets separately.
© CERN for the benefit of the ATLAS collaboration, 2016
