Direct photon production in Pb–Pb collisions at √sNN=2.76 TeV

ALICE Collaboration

doi:10.1016/j.physletb.2016.01.020

Direct photon production in Pb–Pb collisions at √s_NN=2.76 TeV

ALICE Collaboration

Sección de Física

Faculty of Nuclear Sciences and Physical Engineering
Czech Academy of Sciences
Panjab University
CERN
Sezione INFN
Indian Institute of Technology Bombay
Variable Energy Cyclotron Centre
Korea Institute of Science and Technology Information
Yale University
Alikhanov Institute for Theoretical and Experimental Physics
Russian Research Centre Kurchatov Institute
University of Birmingham
Universidad Nacional Autónoma de México
Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi
National Institute for Nuclear Physics
Bogolyubov Institute for Theoretical Physics Nasu
Universidad Autonoma de Sinaloa
Western Norway University of Applied Sciences
Frankfurt Institute for Advanced Studies
University of Bergen
St. Petersburg State University
Universidade de São Paulo
National Institute for Physics and Nuclear Engineering
GSI Helmholtzzentrum für Schwerionenforschung
Ruprecht-Karls-Universität Heidelberg
University of Münster
Ruder Boskovic Institute
Nantes Université
Goethe University Frankfurt
University of Bologna
Technische Universität München
Technical University of Munich
University of Oslo
Oak Ridge National Laboratory
Department of Physics Aligarh Muslim University
Dipartimento di Fisica e Astronomia dell'Università and Sezione INFN
Gangneung-Wonju National University
Konkuk University
University of Jammu
IRFU
Institute of Physics Bhubaneswar
University of Catania
Hungarian Academy of Sciences
Université Clermont Auvergne
Central China Normal University
Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences
Joint Institute for Nuclear Research
University of Copenhagen
Inha University
Université de Strasbourg
Benemérita Universidad Autónoma de Puebla
University of Houston
Wayne State University
Moscow Engineering Physics Institute
Petersburg Nuclear Physics Institute (PNPI)
Institute for Subatomic Physics of Utrecht University
Gauhati University
University of Tsukuba
INFN, Laboratori Nazionali Di Frascati
Bose Institute
National Institute of Science Education and Research
University of Texas at Austin
Lawrence Berkeley National Laboratory
Pavol Jozef Šafárik University
Pusan National University
STFC Daresbury Laboratory
University of Liverpool
National Research Foundation
Purdue University
University of Helsinki
Russian Federal Nuclear Center (VNIIEF)
COMSATS University Islamabad
Ohio State University
Pontifical Catholic Univ. of Peru
University of Tennessee
Sezione INFN
Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear
Technical University of Košice
University of Jyväskylä
Saha Institute of Nuclear Physics
Creighton University
Universite Claude Bernard Lyon 1
Universidade Estadual de Campinas
National Institute for Subatomic Physics
University of Lund
University of Cape Town
Université Grenoble Alpes
CNRS-IN2P3
Georgia State University
Centro de Investigación y de Estudios AVanzados (CINVESTAV)
Institute of Space Science (ISS)
National Centre for Nuclear Studies
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT)
University of Zagreb
Institute for High Energy Physics
Universidad de Santiago de Compostela
RAS - Institute for Nuclear Research
National and Kapodistrian University of Athens
Chicago State University
University of Split
Warsaw University of Technology
A. Alikhanian Yerevan Institute of Physics
Tokyo University
Eberhard Karls Universität Tübingen
Sejong University
Slovak Academy of Sciences
Yonsei University
KTO Karatay University
Fachhochschule Worms
California Polytechnic State University, San Luis Obispo
Suranaree University of Technology
University of South-Eastern Norway
China Institute of Atomic Energy
M.V.Lomonosov Moscow State University
University of the Witwatersrand
Institute of Physics of the Czech Academy of Sciences
University of Rome La Sapienza
Comenius University
Polytechnic University of Bari
Indian Institute of Technology Indore
Hiroshima University
Nagasaki Institute of Applied Science
Budker Institute for Nuclear Physics
University of Rajasthan
Laboratori Nazionali di Legnaro
Centre de calcul de l'IN2P3
Austrian Academy of Sciences

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

243 Scopus citations

Abstract

Direct photon production at mid-rapidity in Pb–Pb collisions at s_NN=2.76 TeV was studied in the transverse momentum range 0.9<p_T<14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e⁺e⁻ pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0–20%, 20–40%, and 40–80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for p_T≳5 GeV/c. Direct photon spectra down to p_T≈1 GeV/c could be extracted for the 20–40% and 0–20% centrality classes. The significance of the direct photon signal for 0.9<p_T<2.1 GeV/c is 2.6σ for the 0–20% class. The spectrum in this p_T range and centrality class can be described by an exponential with an inverse slope parameter of (297±12^stat±41^syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.

Original language	English
Pages (from-to)	235-248
Number of pages	14
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	754
DOIs	https://doi.org/10.1016/j.physletb.2016.01.020
State	Published - 10 Mar 2016

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10.1016/j.physletb.2016.01.020

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@article{200e8882a1cd405d87e142112de0e6f0,

title = "Direct photon production in Pb–Pb collisions at √sNN=2.76 TeV",

abstract = "Direct photon production at mid-rapidity in Pb–Pb collisions at sNN=2.76 TeV was studied in the transverse momentum range 0.9T<14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e− pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0–20\%, 20–40\%, and 40–80\% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT≳5 GeV/c. Direct photon spectra down to pT≈1 GeV/c could be extracted for the 20–40\% and 0–20\% centrality classes. The significance of the direct photon signal for 0.9T<2.1 GeV/c is 2.6σ for the 0–20\% class. The spectrum in this pT range and centrality class can be described by an exponential with an inverse slope parameter of (297±12stat±41syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.",

author = "\{ALICE Collaboration\} and J. Adam and D. Adamov{\'a} and Aggarwal, \{M. M.\} and \{Aglieri Rinella\}, G. and M. Agnello and N. Agrawal and Z. Ahammed and Ahn, \{S. U.\} and S. Aiola and A. Akindinov and Alam, \{S. N.\} and D. Aleksandrov and B. Alessandro and D. Alexandre and \{Alfaro Molina\}, R. and A. Alici and A. Alkin and Almaraz, \{J. R.M.\} and J. Alme and T. Alt and S. Altinpinar and I. Altsybeev and \{Alves Garcia Prado\}, C. and C. Andrei and A. Andronic and V. Anguelov and J. Anielski and T. Anti{\v c}i{\'c} and F. Antinori and P. Antonioli and L. Aphecetche and H. Appelsh{\"a}user and S. Arcelli and R. Arnaldi and Arnold, \{O. W.\} and Arsene, \{I. C.\} and M. Arslandok and B. Audurier and A. Augustinus and R. Averbeck and Awes, \{T. C.\} and Azmi, \{M. D.\} and A. Badal{\`a} and Baek, \{Y. W.\} and S. Bagnasco and R. Bailhache and R. Bala and A. Baldisseri and Baral, \{R. C.\} and Gago, \{A. M.\}",

note = "Publisher Copyright: {\textcopyright} 2016 CERN for the benefit of the ALICE Collaboration",

year = "2016",

month = mar,

day = "10",

doi = "10.1016/j.physletb.2016.01.020",

language = "English",

volume = "754",

pages = "235--248",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

}

TY - JOUR

T1 - Direct photon production in Pb–Pb collisions at √sNN=2.76 TeV

AU - ALICE Collaboration

AU - Adam, J.

AU - Adamová, D.

AU - Aggarwal, M. M.

AU - Aglieri Rinella, G.

AU - Agnello, M.

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahn, S. U.

AU - Aiola, S.

AU - Akindinov, A.

AU - Alam, S. N.

AU - Aleksandrov, D.

AU - Alessandro, B.

AU - Alexandre, D.

AU - Alfaro Molina, R.

AU - Alici, A.

AU - Alkin, A.

AU - Almaraz, J. R.M.

AU - Alme, J.

AU - Alt, T.

AU - Altinpinar, S.

AU - Altsybeev, I.

AU - Alves Garcia Prado, C.

AU - Andrei, C.

AU - Andronic, A.

AU - Anguelov, V.

AU - Anielski, J.

AU - Antičić, T.

AU - Antinori, F.

AU - Antonioli, P.

AU - Aphecetche, L.

AU - Appelshäuser, H.

AU - Arcelli, S.

AU - Arnaldi, R.

AU - Arnold, O. W.

AU - Arsene, I. C.

AU - Arslandok, M.

AU - Audurier, B.

AU - Augustinus, A.

AU - Averbeck, R.

AU - Awes, T. C.

AU - Azmi, M. D.

AU - Badalà, A.

AU - Baek, Y. W.

AU - Bagnasco, S.

AU - Bailhache, R.

AU - Bala, R.

AU - Baldisseri, A.

AU - Baral, R. C.

AU - Gago, A. M.

PY - 2016/3/10

Y1 - 2016/3/10

N2 - Direct photon production at mid-rapidity in Pb–Pb collisions at sNN=2.76 TeV was studied in the transverse momentum range 0.9T<14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e− pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0–20%, 20–40%, and 40–80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT≳5 GeV/c. Direct photon spectra down to pT≈1 GeV/c could be extracted for the 20–40% and 0–20% centrality classes. The significance of the direct photon signal for 0.9T<2.1 GeV/c is 2.6σ for the 0–20% class. The spectrum in this pT range and centrality class can be described by an exponential with an inverse slope parameter of (297±12stat±41syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.

AB - Direct photon production at mid-rapidity in Pb–Pb collisions at sNN=2.76 TeV was studied in the transverse momentum range 0.9T<14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e− pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0–20%, 20–40%, and 40–80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT≳5 GeV/c. Direct photon spectra down to pT≈1 GeV/c could be extracted for the 20–40% and 0–20% centrality classes. The significance of the direct photon signal for 0.9T<2.1 GeV/c is 2.6σ for the 0–20% class. The spectrum in this pT range and centrality class can be described by an exponential with an inverse slope parameter of (297±12stat±41syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.

UR - https://www.scopus.com/pages/publications/85040813298

U2 - 10.1016/j.physletb.2016.01.020

DO - 10.1016/j.physletb.2016.01.020

M3 - Article

AN - SCOPUS:85040813298

SN - 0370-2693

VL - 754

SP - 235

EP - 248

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

ER -

Direct photon production in Pb–Pb collisions at √s_NN=2.76 TeV

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