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Measurement of photon–jet transverse momentum correlations in 5.02 TeV Pb + Pb and pp collisions with ATLAS

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<mark>Journal publication date</mark>10/02/2019
<mark>Journal</mark>Physics Letters B
Number of pages24
Pages (from-to)167-190
Publication StatusPublished
Early online date13/12/18
<mark>Original language</mark>English


Jets created in association with a photon can be used as a calibrated probe to study energy loss in the medium created in nuclear collisions. Measurements of the transverse momentum balance between isolated photons and inclusive jets are presented using integrated luminosities of 0.49 nb(-1) of Pb + Pb collision data at root(NN)-N-s = 5.02 TeV and 25 pb(-1) of pp collision data at. root s= 5.02 TeV recorded with the ATLAS detector at the LHC. Photons with transverse momentum 63.1 <p(T)(gamma) <200 GeV and vertical bar eta(gamma vertical bar) <2.37 are paired with all jets in the event that have p(T)(jet) > 31.6 GeV and pseudorapidity vertical bar eta(Jet)vertical bar <2.8. The transverse momentum balance given by the jet-to-photon p(T) ratio, x(j gamma), is measured for pairs with azimuthal opening angle Delta phi > 7 pi/8. Distributions of the per-photon jet yield as a function of x(j gamma), (1/N-gamma)(dN/dx(j gamma)), are corrected for detector effects via a two-dimensional unfolding procedure and reported at the particle level. In pp collisions, the distributions are well described by Monte Carlo event generators. In Pb + Pb collisions, the x(j gamma) distribution is modified from that observed in pp collisions with increasing centrality, consistent with the picture of parton energy loss in the hot nuclear medium. The data are compared with a suite of energy-loss models and calculations. (C) 2018 The Author(s). Published by Elsevier B.V.

Bibliographic note

Export Date: 23 January 2019 CODEN: PYLBA Correspondence Address: Fiolhais, M.C.N.; Borough of Manhattan Community College, City University of New YorkUnited States Funding details: Ministerstwo Nauki i Szkolnictwa Wyższego, MNiSW Funding details: Australian Research Council Funding details: Fuel Cell Technologies Program, FCT Funding details: Joint Institute for Nuclear Research, JINR Funding details: British Columbia Knowledge Development Fund Funding details: German -Israeli Foundation for Scientific Research and Development Funding details: TRIUMF Funding details: Generalitat de Catalunya Funding details: Ministry of Science and Technology, MOST Funding details: Iowa Science Foundation, ISF Funding details: Ministerstvo Průmyslu a Obchodu, MPO Funding details: Alabama Space Grant Consortium Funding details: American Roentgen Ray Society Funding details: School for Advanced Research Funding details: Japan Society for the Promotion of Science Funding details: Türkiye Atom Enerjisi Kurumu, TAEK Funding details: Campus France Funding details: Nella and Leon Benoziyo Center for Neurological Diseases, Weizmann Institute of Science Funding details: European Research Council Funding details: Labex Funding details: European Cooperation in Science and Technology Funding details: Science and Technology Facilities Council Funding details: Leverhulme Trust Funding details: Human Growth Foundation Funding details: Thales Group, Thales Funding details: Fundação de Amparo à Pesquisa do Estado de São Paulo Funding details: Narodowym Centrum Nauki, NCN Funding details: Max -Planck -Gesellschaft, MPG Funding details: Bundesministerium für Bildung und Forschung, BMBF Funding details: Natural Sciences and Engineering Research Council of Canada, NRC Funding details: Compute Canada Funding details: Brookhaven National Laboratory Funding details: Instituto Nazionale di Fisica Nucleare, INFN Funding details: Danmarks Grundforskningsfond Funding details: Juvenile Diabetes Research Foundation United States of America Funding details: Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq Funding details: Agence Nationale de la Recherche Funding details: Marianne and Marcus Wallenberg Foundation Funding details: Chinese Academy of Sciences, CAS Funding details: Departamento Administrativo de Ciencia, Tecnología e Innovación, COLCIENCIAS Funding details: European Geosciences Union Funding details: CERN Funding details: Poultry Industry Council, PIC Funding details: Arizona -Nevada Academy of Science, ANAS Funding details: General Secretariat for Research and Technology, GSRT Funding details: H2020 Marie Skłodowska -Curie Actions Funding details: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung Funding details: Singapore Eye Research Institute Funding details: Ministry of Education, Culture, Sports, Science and Technology Funding details: Ministry of Education and Science, MES Funding details: Agencia Nacional de Promoción Científica y Tecnológica, ANPCyT Funding details: Centre National pour la Recherche Scientifique et Technique, CNRST Funding text 1: We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT , Argentina; YerPhI , Armenia; ARC , Australia; BMWFW and FWF , Austria; ANAS , Azerbaijan; SSTC , Belarus; CNPq and FAPESP , Brazil; NSERC , NRC and CFI , Canada; CERN ; CONICYT , Chile; CAS , MOST and NSFC , China; COLCIENCIAS , Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC , Denmark; IN2P3 -CNRS , CEA -DRF/IRFU , France; SRNSFG , Georgia; BMBF , HGF , and MPG , Germany; GSRT , Greece; RGC , Hong Kong SAR, China; ISF and Benoziyo Center , Israel; INFN , Italy; MEXT and JSPS , Japan; CNRST , Morocco; NWO , Netherlands; RCN , Norway; MNiSW and NCN , Poland; FCT , Portugal; MNE/IFA , Romania; MES of Russia and NRC KI , Russian Federation; JINR ; MESTD , Serbia; MSSR , Slovakia; ARRS and MIZŠ , Slovenia; DST/NRF , South Africa; MINECO , Spain; SRC and Wallenberg Foundation , Sweden; SERI , SNSF and Cantons of Bern and Geneva , Switzerland; MOST , Taiwan; TAEK , Turkey; STFC , United Kingdom; DOE and NSF , United States of America. In addition, individual groups and members have received support from BCKDF , Canarie , CRC and Compute Canada , Canada; COST , ERC , ERDF , Horizon 2020 , and Marie Skłodowska -Curie Actions , European Union; Investissements d' Avenir Labex and Idex , ANR , France; DFG and AvH Foundation , Germany; Herakleitos, Thales and Aristeia programmes co -financed by EU -ESF and the Greek NSRF , Greece; BSF -NSF and GIF , Israel; CERCA Programme Generalitat de Catalunya , Spain; The Royal Society and Leverhulme Trust , United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN , the ATLAS Tier -1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC -IN2P3 (France), KIT/GridKA (Germany), INFN -CNAF (Italy), NL -T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier -2 facilities worldwide and large non -WLCG resource providers. Major contributors of computing resources are listed in Ref. [61] .