Published December 14, 2018 | Version Published + Submitted
Journal Article Open

Observation of Medium-Induced Modifications of Jet Fragmentation in Pb-Pb Collisions at √s_(NN) = 5.02  TeV Using Isolated Photon-Tagged Jets

Abstract

Measurements of fragmentation functions for jets associated with an isolated photon are presented for the first time in pp and Pb-Pb collisions. The analysis uses data collected with the CMS detector at the CERN LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Fragmentation functions are obtained for jets with p^(jet)_T > 30  GeV/c in events containing an isolated photon with p^γ_T > 60  GeV/c, using charged tracks with transverse momentum p^(trk)_T > 1  GeV/c in a cone around the jet axis. The association with an isolated photon constrains the initial pT and azimuthal angle of the parton whose shower produced the jet. For central Pb-Pb collisions, modifications of the jet fragmentation functions are observed when compared to those measured in pp collisions, while no significant differences are found in the 50% most peripheral collisions. Jets in central Pb-Pb events show an excess (depletion) of low (high) p_T particles, with a transition around 3  GeV/c. This measurement shows for the first time the in-medium shower modifications of partons (quark dominated) with well-defined initial kinematics. It constitutes a new well-controlled reference for testing theoretical models of the parton passage through the quark-gluon plasma.

Additional Information

© 2018 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3. Received 15 January 2018; revised manuscript received 16 October 2018; published 14 December 2018. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centers and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan);MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, Federal Agency of Atomic Energy of the Russian Federation RosAtom, RAS, RFBR and RAEP (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA).

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Published - PhysRevLett.121.242301.pdf

Submitted - 1801.04895.pdf

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Identifiers

Eprint ID
92037
Resolver ID
CaltechAUTHORS:20190103-130033571

Related works

Funding

Bundesministerium für Wissenschaft, Forschung Und Wirtschaft (BMWFW)
FWF Der Wissenschaftsfonds
Fonds de la Recherche Scientifique (FNRS)
Fonds Wetenschappelijk Onderzoek (FWO)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)
Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Ministry of Education and Science (Bulgaria)
CERN
Chinese Academy of Sciences
Ministry of Science and Technology (China)
National Natural Science Foundation of China
Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS)
Ministry of Science, Education and Sport (Croatia)
Croatian Science Foundation
Research Promotion Foundation (Cyprus)
Secretaría Nacional de Educación Superior, Ciencia, Tecnología e Innovación (SENESCYT)
Ministry of Education and Research (Estonia)
Estonian Research Council
European Regional Development Fund (Estonia)
Academy of Finland
Ministry of Education and Culture (Finland)
Helsinki Institute of Physics
Commissariat a l'Energie Atomique (CEA)
Centre National de la Recherche Scientifique (CNRS)
Institut National de Physique Nucléaire et de Physique des Particules (IN2P3)
Bundesministerium für Bildung und Forschung (BMBF)
Deutsche Forschungsgemeinschaft (DFG)
Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF)
General Secretariat for Research and Technology (GSRT)
National Research, Development and Innovation Office (Hungary)
Department of Atomic Energy (India)
Department of Science and Technology (India)
Institute for Studies in Theoretical Physics and Mathematics (Iran)
Science Foundation, Ireland
Istituto Nazionale di Fisica Nucleare (INFN)
Ministry of Science, ICT and Future Planning (Korea)
National Research Foundation of Korea
Lithuanian Academy of Sciences
Ministry of Education (Malaysia)
University of Malaya
Benemérita Universidad Autónoma de Puebla (BUAP)
Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV)
Consejo Nacional de Ciencia y Tecnología (CONACYT)
Laboratorio Nacional de Supercómputo (LNS)
Secretaría de Educación Pública (SEP)
Ministero della Scienza del Montenegro (MOS)
Universidad Autónoma de San Luis Potosí Inicio-Facultad de Ingeniería (UASLP-FAI)
Ministry of Business, Innovation and Employment (New Zealand)
Atomic Energy Commission (Pakistan)
Ministry of Science and Higher Education (Poland)
National Science Centre (Poland)
Fundação para a Ciência e Tecnologia (FCT)
Joint Institute for Nuclear Research (JINR)
Russian Ministry of Education and Sciences (MON)
RosAtom
Russian Academy of Sciences
Russian Foundation for Basic Research
Russian Academic Excellence Project (RAEP)
National Research Center, Kurchatov Institute (Russia)
Ministry of Education, Science and Technological Development (Serbia)
Secretaría de Estado de Investigación, Desarrollo e Innovación (SEIDI)
Centro Nacional de Física de Partículas, Astropartículas y Nuclear (CPAN)
Plan de Ciencia, Tecnología e Innovación (PCtI)
Fondo Europeo de Desarrollo Regional (FEDER)
Swiss Funding Agencies
Ministry of Science and Technology (Taipei)
Thailand Center of Excellence in Physics
Institute for the Promotion of Teaching Science and Technology (Thailand)
Special Task Force for Activating Research (Thailand)
National Science and Technology Development Agency (Thailand)
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK)
Türkiye Atom Enerjisi Kurumu (TAEK)
National Academy of Sciences (Ukraine)
State Fund for Fundamental Research (Ukraine)
Science and Technology Facilities Council (STFC)
Department of Energy (DOE)
NSF
SCOAP3

Dates

Created
2019-01-03
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Updated
2021-11-16
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