https://doi.org/10.1140/epjc/s10052-011-1594-5
Regular Article - Experimental Physics
Strange particle production in proton–proton collisions at 
with ALICE at the LHC
The ALICE Collaboration
1
Department of Physics and Technology, University of Bergen, Bergen, Norway
2
Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba
3
Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic
4
Yale University, New Haven, CT, USA
5
Physics Department, Panjab University, Chandigarh, India
6
European Organization for Nuclear Research (CERN), Geneva, Switzerland
7
KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary
8
Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico
9
Variable Energy Cyclotron Centre, Kolkata, India
10
Department of Physics, Aligarh Muslim University, Aligarh, India
11
Gangneung-Wonju National University, Gangneung, South Korea
12
Institute for Theoretical and Experimental Physics, Moscow, Russia
13
Russian Research Centre Kurchatov Institute, Moscow, Russia
14
Sezione INFN, Turin, Italy
15
Dipartimento di Fisica dell’Università, Bologna, Italy
16
Sezione INFN, Bologna, Italy
17
Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine
18
Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
19
Dipartimento Interateneo di Fisica ‘M. Merlin’, Bari, Italy
20
Sezione INFN, Bari, Italy
21
Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
22
V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia
23
National Institute for Physics and Nuclear Engineering, Bucharest, Romania
24
Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
25
Department of Physics, Ohio State University, Columbus, OH, USA
26
Rudjer Bošković Institute, Zagreb, Croatia
27
Dipartimento di Fisica dell’Università, Padova, Italy
28
Sezione INFN, Padova, Italy
29
SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France
30
Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
31
Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, Grenoble, France
32
Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France
33
Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
34
Oak Ridge National Laboratory, Oak Ridge, TN, USA
35
Helsinki Institute of Physics (HIP), Jyvaskyla, Finland
36
University of Jyvaskyla, Jyvaskyla, Finland
37
Sezione INFN, Catania, Italy
38
Dipartimento di Fisica, Sperimentale dell’Università, Turin, Italy
39
Centro Fermi—Centro Studi e Ricerche e Museo Storico della Fisica “Enrico Fermi”, Rome, Italy
40
Commissariat à l’Energie Atomique, IRFU, Saclay, France
41
Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Clermont-Ferrand, France
42
CNRS–IN2P3, Université Blaise Pascal, Clermont-Ferrand, France
43
Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia
44
Dipartimento di Fisica e Astronomia dell’Università, Catania, Italy
45
School of Physics and Astronomy, University of Birmingham, Birmingham, UK
46
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
47
Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
48
Joint Institute for Nuclear Research (JINR), Dubna, Russia
49
Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
50
Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France
51
Wayne State University, Detroit, MI, USA
52
Petersburg Nuclear Physics Institute, Gatchina, Russia
53
Physics Department, University of Jammu, Jammu, India
54
Laboratori Nazionali di Frascati, INFN, Frascati, Italy
55
Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic
56
Nikhef, National Institute for Subatomic Physics, Amsterdam, The Netherlands
57
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
58
University of Houston, Houston, TX, USA
59
Moscow Engineering Physics Institute, Moscow, Russia
60
Institute for High Energy Physics, Protvino, Russia
61
Faculty of Science, P.J. Šafárik University, Košice, Slovakia
62
Saha Institute of Nuclear Physics, Kolkata, India
63
Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France
64
Department of Physics, University of Oslo, Oslo, Norway
65
Dipartimento di Fisica dell’Università, Trieste, Italy
66
Sezione INFN, Trieste, Italy
67
Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
68
Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
69
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
70
Physics Department, iThemba Laboratories, University of Cape Town, Cape Town, South Africa
71
Hua-Zhong Normal University, Wuhan, China
72
Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru
73
Physics Department, Creighton University, Omaha, NE, USA
74
Université de Lyon, Université Lyon 1, Villeurbanne, France
75
CNRS/IN2P3, IPN-Lyon, Villeurbanne, France
76
Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
77
Nikhef, National Institute for Subatomic Physics, Utrecht, The Netherlands
78
Institute for Subatomic Physics of Utrecht University, Utrecht, The Netherlands
79
Division of Experimental High Energy Physics, University of Lund, Lund, Sweden
80
University of Tsukuba, Tsukuba, Japan
81
Sezione INFN, Cagliari, Italy
82
Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Merida, Mexico
83
Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
84
Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale, Alessandria, Italy
85
Gruppo Collegato INFN, Alessandria, Italy
86
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
87
Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy
88
Institute of Space Sciences (ISS), Bucharest, Romania
89
Institute of Physics, Bhubaneswar, India
90
Universidade de São Paulo (USP), São Paulo, Brazil
91
Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università, Salerno, Italy
92
Gruppo Collegato INFN, Salerno, Italy
93
Dipartimento di Fisica dell’Università, Cagliari, Italy
94
Soltan Institute for Nuclear Studies, Warsaw, Poland
95
Sezione INFN, Rome, Italy
96
Faculty of Engineering, Bergen University College, Bergen, Norway
97
Institute for Nuclear Research, Academy of Sciences, Moscow, Russia
98
University of Athens, Physics Department, Athens, Greece
99
Warsaw University of Technology, Warsaw, Poland
100
Universidad Autónoma de Sinaloa, Culiacan, Mexico
101
Technical University of Split FESB, Split, Croatia
102
Yerevan Physics Institute, Yerevan, Armenia
103
University of Tokyo, Tokyo, Japan
104
Department of Physics, Sejong University, Seoul, South Korea
105
Lawrence Berkeley National Laboratory, Berkeley, CA, USA
106
Indian Institute of Technology, Mumbai, India
107
Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany
108
Yonsei University, Seoul, South Korea
109
Zentrum für Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms, Germany
110
California Polytechnic State University, San Luis Obispo, CA, USA
111
China Institute of Atomic Energy, Beijing, China
112
Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
113
University of Tennessee, Knoxville, TN, USA
114
Dipartimento di Fisica dell’Università ‘La Sapienza’, Rome, Italy
115
Hiroshima University, Hiroshima, Japan
116
Lawrence Livermore National Laboratory, Livermore, CA, USA
117
Budker Institute for Nuclear Physics, Novosibirsk, Russia
118
Physics Department, University of Rajasthan, Jaipur, India
119
Purdue University, West Lafayette, IN, USA
120
Centre de Calcul de l’IN2P3, Villeurbanne, France
121
Pusan National University, Pusan, South Korea
* e-mail: Paul.Kuijer@nikhef.nl
Received:
15
December
2010
Revised:
9
February
2011
Published online:
30
March
2011
The production of mesons containing strange quarks (
, φ) and both singly and doubly strange baryons (
, 
, and 
) are measured at mid-rapidity in pp collisions at 
= 0.9 
with the ALICE experiment at the LHC. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (dN/dy) and transverse momentum spectra at mid-rapidity for inelastic pp collisions are presented. For mesons, we report yields (〈dN/dy〉) of 0.184±0.002(stat.)±0.006(syst.) for and 0.021±0.004(stat.)±0.003(syst.) for φ. For baryons, we find 〈dN/dy〉=0.048±0.001(stat.)±0.004(syst.) for , 0.047±0.002(stat.)±0.005(syst.) for and 0.0101±0.0020(stat.)±0.0009(syst.) for . The results are also compared with predictions for identified particle spectra from QCD-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.
© Springer-Verlag / Società Italiana di Fisica, 2011
