https://doi.org/10.1140/epjc/s10052-014-3077-y
Regular Article - Experimental Physics
Event-by-event mean pT fluctuations in pp and Pb–Pb collisions at the LHC
1
A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation, Yerevan, Armenia
2
Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
3
Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine
4
Department of Physics and Centre for Astroparticle Physics and Space Science (CAPSS), Bose Institute, Kolkata, India
5
Budker Institute for Nuclear Physics, Novosibirsk, Russia
6
California Polytechnic State University, San Luis Obispo, CA, USA
7
Central China Normal University, Wuhan, China
8
Centre de Calcul de l’IN2P3, Villeurbanne, France
9
Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba
10
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
11
Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico
12
Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi”, Rome, Italy
13
Chicago State University, Chicago, USA
14
Commissariat à l’Energie Atomique, IRFU, Saclay, France
15
COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan
16
Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
17
Department of Physics and Technology, University of Bergen, Bergen, Norway
18
Department of Physics, Aligarh Muslim University, Aligarh, India
19
Department of Physics, Ohio State University, Columbus, OH, USA
20
Department of Physics, Sejong University, Seoul, South Korea
21
Department of Physics, University of Oslo, Oslo, Norway
22
Dipartimento di Fisica dell’Università ‘La Sapienza’ and Sezione INFN, Rome, Italy
23
Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy
24
Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy
25
Dipartimento di Fisica dell’Università and Sezione INFN, Turin, Italy
26
Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Bologna, Italy
27
Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy
28
Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Padua, Italy
29
Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Gruppo Collegato INFN, Salerno, Italy
30
Dipartimento di Scienze e Innovazione Tecnologica dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy
31
Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy
32
Division of Experimental High Energy Physics, University of Lund, Lund, Sweden
33
Eberhard Karls Universität Tübingen, Tübingen, Germany
34
European Organization for Nuclear Research (CERN), Geneva, Switzerland
35
Faculty of Engineering, Bergen University College, Bergen, Norway
36
Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
37
Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic
38
Faculty of Science, P.J. Šafárik University, Kosice, Slovakia
39
Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
40
Gangneung-Wonju National University, Gangneung, South Korea
41
Department of Physics, Gauhati University, Guwahati, India
42
Helsinki Institute of Physics (HIP), Helsinki, Finland
43
Hiroshima University, Hiroshima, Japan
44
Indian Institute of Technology Bombay (IIT), Mumbai, India
45
Indian Institute of Technology Indore (IITI), Indore, India
46
Inha University, Inchon, South Korea
47
Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France
48
Institut für Informatik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
49
Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
50
Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
51
Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France
52
Institute for Nuclear Research, Academy of Sciences, Moscow, Russia
53
Institute for Subatomic Physics of Utrecht University, Utrecht, The Netherlands
54
Institute for Theoretical and Experimental Physics, Moscow, Russia
55
Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
56
Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
57
Institute of Physics, Bhubaneswar, India
58
Institute of Space Science (ISS), Bucharest, Romania
59
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
60
Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico
61
iThemba LABS, National Research Foundation, Somerset West, South Africa
62
Joint Institute for Nuclear Research (JINR), Dubna, Russia
63
Konkuk University, Seoul, South Korea
64
Korea Institute of Science and Technology Information, Taejeon, South Korea
65
KTO Karatay University, Konya, Turkey
66
Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS-IN2P3, Clermont-Ferrand, France
67
Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS-IN2P3, Grenoble, France
68
Laboratori Nazionali di Frascati, INFN, Frascati, Italy
69
Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy
70
Lawrence Berkeley National Laboratory, Berkeley, CA, USA
71
Lawrence Livermore National Laboratory, Livermore, CA, USA
72
Moscow Engineering Physics Institute, Moscow, Russia
73
National Centre for Nuclear Studies, Warsaw, Poland
74
National Institute for Physics and Nuclear Engineering, Bucharest, Romania
75
National Institute of Science Education and Research, Bhubaneswar, India
76
Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
77
Nikhef, National Institute for Subatomic Physics, Amsterdam, The Netherlands
78
Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, UK
79
Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic
80
Oak Ridge National Laboratory, Oak Ridge, TN, USA
81
Petersburg Nuclear Physics Institute, Gatchina, Russia
82
Physics Department, Creighton University, Omaha, NE, USA
83
Physics Department, Panjab University, Chandigarh, India
84
Physics Department, University of Athens, Athens, Greece
85
Physics Department, University of Cape Town, Cape Town, South Africa
86
Physics Department, University of Jammu, Jammu, India
87
Physics Department, University of Rajasthan, Jaipur, India
88
Physik Department, Technische Universität München, Munich, Germany
89
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
90
Politecnico di Torino, Turin, Italy
91
Purdue University, West Lafayette, IN, USA
92
Pusan National University, Pusan, South Korea
93
Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
94
Rudjer Bošković Institute, Zagreb, Croatia
95
Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
96
Russian Research Centre Kurchatov Institute, Moscow, Russia
97
Saha Institute of Nuclear Physics, Kolkata, India
98
School of Physics and Astronomy, University of Birmingham, Birmingham, UK
99
Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru
100
Sezione INFN, Bari, Italy
101
Sezione INFN, Bologna, Italy
102
Sezione INFN, Cagliari, Italy
103
Sezione INFN, Catania, Italy
104
Sezione INFN, Padua, Italy
105
Sezione INFN, Rome, Italy
106
Sezione INFN, Trieste, Italy
107
Sezione INFN, Turin, Italy
108
SSC IHEP of NRC Kurchatov institute, Protvino, Russia
109
SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France
110
Suranaree University of Technology, Nakhon Ratchasima, Thailand
111
Technical University of Split FESB, Split, Croatia
112
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Kracòw, Poland
113
Physics Department, The University of Texas at Austin, Austin, TX, USA
114
Universidad Autónoma de Sinaloa, Culiacán, Mexico
115
Universidade de São Paulo (USP), São Paulo, Brazil
116
Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
117
University of Houston, Houston, TX, USA
118
University of Jyväskylä, Jyväskylä, Finland
119
University of Liverpool, Liverpool, UK
120
University of Tennessee, Knoxville, TN, USA
121
University of Tokyo, Tokyo, Japan
122
University of Tsukuba, Tsukuba, Japan
123
University of Zagreb, Zagreb, Croatia
124
Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France
125
V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia
126
Variable Energy Cyclotron Centre, Kolkata, India
127
Vestfold University College, Tonsberg, Norway
128
Warsaw University of Technology, Warsaw, Poland
129
Wayne State University, Detroit, MI, USA
130
Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary
131
Yale University, New Haven, CT, USA
132
Yonsei University, Seoul, South Korea
133
Zentrum für Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms, Germany
134
CERN, 1211, Geneva 23, Switzerland
* e-mail: alice-publications@cern.ch
Received:
22
July
2014
Accepted:
12
September
2014
Published online:
15
October
2014
Event-by-event fluctuations of the mean transverse momentum of charged particles produced in pp collisions at √s = 0.9, 2.76 and 7 TeV, and Pb–Pb collisions at √sNN = 2.76 TeV are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations indicative of correlated particle emission are observed in all systems. The results in pp collisions show little dependence on collision energy. The Monte Carlo event generators PYTHIA and PHOJET are in qualitative agreement with the data. Peripheral Pb–Pb data exhibit a similar multiplicity dependence as that observed in pp. In central Pb–Pb, the results deviate from this trend, featuring a significant reduction of the fluctuation strength. The results in Pb–Pb are in qualitative agreement with previous measurements in Au–Au at lower collision energies and with expectations from models that incorporate collective phenomena.
© SIF and Springer-Verlag Berlin Heidelberg, 2014
