Event-shape and multiplicity dependence of freeze-out radii in pp collisions at √s = 7 TeV

The ALICE collaboration

doi:10.1007/JHEP09(2019)108

Event-shape and multiplicity dependence of freeze-out radii in pp collisions at √s = 7 TeV

The ALICE collaboration

Sección de Física

CERN
Variable Energy Cyclotron Centre
Czech Academy of Sciences
Goethe University Frankfurt
Lund University
Panjab University
Polytechnic University of Turin
Indian Institute of Technology Bombay
Aligarh Muslim University
Korea Institute of Science and Technology Information
Yale University
Alikhanov Institute for Theoretical and Experimental Physics
GSI Helmholtz Centre for Heavy Ion Research
Universidade Estadual de Campinas
Russian Research Centre Kurchatov Institute
National Institute for Nuclear Physics
Central China Normal University
Universidad Nacional Autónoma de México
COMSATS University Islamabad
Enrico Fermi Center
NASU - Bogolyubov Institute for Theoretical Physics
University of Bergen
St. Petersburg State University
Horia Hulubei National Institute of Physics and Nuclear Engineering
University of Birmingham
University of Münster
Heidelberg University
Creighton University
Ruder Boskovic Institute
University of Houston
Lawrence Berkeley National Laboratory
Nantes Université
University of Oslo
Gangneung-Wonju National University
Inha University
University of Jammu
Commissariat à l’énergie atomique et aux énergies alternatives
University of Bonn
Homi Bhabha National Institute
Hungarian Academy of Sciences
STFC Daresbury Laboratory
CNRS
Wayne State University
Joint Institute for Nuclear Research
University of Copenhagen
Utrecht University
Université de Strasbourg
Benemerita Universidad Autonoma de Puebla
Universidad Autonoma de Sinaloa
Moscow Engineering Physics Institute
RAS - Saint Petersburg Nuclear Physics Institute
University of Tennessee, Knoxville
Gauhati University
Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences
Faculty of Nuclear Sciences and Physical Engineering
Technical University of Munich
Technische Universität München
Bose Institute
University of Texas at Austin
University of Pavia
Pavol Jozef Šafárik University
University of Brescia
University of Liverpool
Universidade de São Paulo
University of Helsinki
All-Russian Scientific Research Institute of Experimental Physics
Austrian Academy of Sciences
University of Tsukuba
National Research Foundation
Ohio State University
Technical University of Kosice
National Institute for Subatomic Physics
Pontificia Universidad Católica del Perú
Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear
University of Jyväskylä
Universite Claude Bernard Lyon 1
University of Cape Town
Université Grenoble Alpes
Centre de calcul de l'IN2P3
Oak Ridge National Laboratory
University of Eastern Piedmont
Universidade Federal do ABC
Warsaw University of Technology
Institute for Space Sciences
Indian Institute of Technology Indore
National Centre for Nuclear Research
University of Zagreb
Pusan National University
Institute for High Energy Physics
RAS - Institute for Nuclear Research
National and Kapodistrian University of Athens
Chicago State University
Universidade Federal do Rio Grande do Sul
University of Split
A. Alikhanian Yerevan Institute of Physics
The University of Tokyo
Nagasaki Institute of Applied Science
Western Norway University of Applied Sciences
Centro de Investigacion y de Estudios Avanzados del Instituto Politécnico Nacional
Sejong University
Slovak Academy of Sciences
Yonsei University
KTO Karatay University
Zentrum für Technologietransfer und Telekommunikation (ZTT)
Jeonbuk National University
California Polytechnic State University, San Luis Obispo
Suranaree University of Technology
University of South-Eastern Norway
China National Nuclear Corporation
Lomonosov Moscow State University
University of Foggia
University of Rome La Sapienza
Comenius University
RAS - Budker Institute of Nuclear Physics
University of Rajasthan
University of Wrocław
National Nuclear Research Center
University of Tübingen
Hiroshima University
Nara Women's University
Chinese Academy of Sciences
Indonesian Institute of Sciences
University of California at Berkeley
Centre de Calcul de l’IN2P3
University of the Witwatersrand
University of Science and Technology of China

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q ∝ 1/R. It was previously observed that in pp collisions at s = 7TeV the average pair transverse momentum k_T range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity S_T into spherical (S_T > 0:7) and jet-like (S_T < 0:3) events a method was developed that allows for the determination of source radii for much larger values of k_T for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the k_T dependence of the radii. The emission source size in spherical events shows a substantially diminished k_T dependence, while jet-like events show indications of a negative trend with respect to k_T in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one. [Figure not available: see fulltext.].

Original language	English
Article number	108
Journal	Journal of High Energy Physics
Volume	2019
Issue number	9
DOIs	https://doi.org/10.1007/JHEP09(2019)108
State	Published - 1 Sep 2019

Keywords

Heavy Ion Experiments
Particle correlations and fluctuations

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10.1007/JHEP09(2019)108

Cite this

@article{131e1171b6da4a99907cd38a6016da23,

title = "Event-shape and multiplicity dependence of freeze-out radii in pp collisions at √s = 7 TeV",

abstract = "Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q ∝ 1/R. It was previously observed that in pp collisions at s = 7TeV the average pair transverse momentum kT range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity ST into spherical (ST > 0:7) and jet-like (ST < 0:3) events a method was developed that allows for the determination of source radii for much larger values of kT for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the kT dependence of the radii. The emission source size in spherical events shows a substantially diminished kT dependence, while jet-like events show indications of a negative trend with respect to kT in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one. [Figure not available: see fulltext.].",

keywords = "Heavy Ion Experiments, Particle correlations and fluctuations",

author = "\{The ALICE collaboration\} and S. Acharya and D. Adamov{\'a} and Adhya, \{S. P.\} and A. Adler and J. Adolfsson and Aggarwal, \{M. M.\} and \{Aglieri Rinella\}, G. and M. Agnello and N. Agrawal and Z. Ahammed and S. Ahmad and Ahn, \{S. U.\} and S. Aiola and A. Akindinov and M. Al-Turany and Alam, \{S. N.\} and Albuquerque, \{D. S.D.\} and D. Aleksandrov and B. Alessandro and Alfanda, \{H. M.\} and \{Alfaro Molina\}, R. and Y. Ali and A. Alici and A. Alkin and J. Alme and T. Alt and L. Altenkamper and I. Altsybeev and Anaam, \{M. N.\} and C. Andrei and D. Andreou and Andrews, \{H. A.\} and A. Andronic and M. Angeletti and V. Anguelov and C. Anson and T. Anti{\v c}i{\'c} and F. Antinori and P. Antonioli and R. Anwar and N. Apadula and L. Aphecetche and H. Appelsh{\"a}user and S. Arcelli and R. Arnaldi and Arsene, \{I. C.\} and M. Arslandok and A. Augustinus and \{Bazo Alba\}, \{J. L.\} and Gago, \{A. M.\}",

note = "Publisher Copyright: {\textcopyright} 2019, The Author(s).",

year = "2019",

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doi = "10.1007/JHEP09(2019)108",

language = "English",

volume = "2019",

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T1 - Event-shape and multiplicity dependence of freeze-out radii in pp collisions at √s = 7 TeV

AU - The ALICE collaboration

AU - Acharya, S.

AU - Adamová, D.

AU - Adhya, S. P.

AU - Adler, A.

AU - Adolfsson, J.

AU - Aggarwal, M. M.

AU - Aglieri Rinella, G.

AU - Agnello, M.

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahmad, S.

AU - Ahn, S. U.

AU - Aiola, S.

AU - Akindinov, A.

AU - Al-Turany, M.

AU - Alam, S. N.

AU - Albuquerque, D. S.D.

AU - Aleksandrov, D.

AU - Alessandro, B.

AU - Alfanda, H. M.

AU - Alfaro Molina, R.

AU - Ali, Y.

AU - Alici, A.

AU - Alkin, A.

AU - Alme, J.

AU - Alt, T.

AU - Altenkamper, L.

AU - Altsybeev, I.

AU - Anaam, M. N.

AU - Andrei, C.

AU - Andreou, D.

AU - Andrews, H. A.

AU - Andronic, A.

AU - Angeletti, M.

AU - Anguelov, V.

AU - Anson, C.

AU - Antičić, T.

AU - Antinori, F.

AU - Antonioli, P.

AU - Anwar, R.

AU - Apadula, N.

AU - Aphecetche, L.

AU - Appelshäuser, H.

AU - Arcelli, S.

AU - Arnaldi, R.

AU - Arsene, I. C.

AU - Arslandok, M.

AU - Augustinus, A.

AU - Bazo Alba, J. L.

AU - Gago, A. M.

PY - 2019/9/1

Y1 - 2019/9/1

N2 - Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q ∝ 1/R. It was previously observed that in pp collisions at s = 7TeV the average pair transverse momentum kT range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity ST into spherical (ST > 0:7) and jet-like (ST < 0:3) events a method was developed that allows for the determination of source radii for much larger values of kT for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the kT dependence of the radii. The emission source size in spherical events shows a substantially diminished kT dependence, while jet-like events show indications of a negative trend with respect to kT in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one. [Figure not available: see fulltext.].

AB - Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q ∝ 1/R. It was previously observed that in pp collisions at s = 7TeV the average pair transverse momentum kT range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity ST into spherical (ST > 0:7) and jet-like (ST < 0:3) events a method was developed that allows for the determination of source radii for much larger values of kT for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the kT dependence of the radii. The emission source size in spherical events shows a substantially diminished kT dependence, while jet-like events show indications of a negative trend with respect to kT in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one. [Figure not available: see fulltext.].

KW - Heavy Ion Experiments

KW - Particle correlations and fluctuations

UR - https://www.scopus.com/pages/publications/85074488241

U2 - 10.1007/JHEP09(2019)108

DO - 10.1007/JHEP09(2019)108

M3 - Article

AN - SCOPUS:85074488241

SN - 1126-6708

VL - 2019

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 9

M1 - 108

ER -

Event-shape and multiplicity dependence of freeze-out radii in pp collisions at √s = 7 TeV

Abstract

Keywords

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