Abstract
Charge-dependent azimuthal correlations of same- and opposite-sign pairs with respect to the second- and third-order event planes have been measured in pPb collisions at sNN=8.16TeV and PbPb collisions at 5.02 TeV with the CMS experiment at the LHC. The measurement is motivated by the search for the charge separation phenomenon predicted by the chiral magnetic effect (CME) in heavy ion collisions. Three- and two-particle azimuthal correlators are extracted as functions of the pseudorapidity difference, the transverse momentum (pT) difference, and the pT average of same- and opposite-charge pairs in various event multiplicity ranges. The data suggest that the charge-dependent three-particle correlators with respect to the second- and third-order event planes share a common origin, predominantly arising from charge-dependent two-particle azimuthal correlations coupled with an anisotropic flow. The CME is expected to lead to a v2-independent three-particle correlation when the magnetic field is fixed. Using an event shape engineering technique, upper limits on the v2-independent fraction of the three-particle correlator are estimated to be 13% for pPb and 7% for PbPb collisions at 95% confidence level. The results of this analysis, both the dominance of two-particle correlations as a source of the three-particle results and the similarities seen between PbPb and pPb, provide stringent constraints on the origin of charge-dependent three-particle azimuthal correlations and challenge their interpretation as arising from a chiral magnetic effect in heavy ion collisions.
| Original language | English |
|---|---|
| Journal | Physical Review C |
| Volume | 97 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 23 Apr 2018 |
Bibliographical note
Publisher Copyright:©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.
Funding
Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Weten-schap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS program of the Foundation for Polish Science, cofinanced from European Union, Regional Development Fund, the Mobility Plus program of the Ministry of Science and Higher Education, the National Science Center (Poland), Harmonia Contract No. 2014/14/M/ST2/00428, Opus Contracts No. 2014/13/B/ST2/02543, No. 2014/15/B/ST2/03998, and No. 2015/19/B/ST2/02861, Sonata-bis Contract No. 2012/07/E/ST2/01406; the National Priorities Research Program by Qatar National Research Fund; the Programa Clarín-COFUND del Principado de Asturias; the Thalis and Aristeia programs cofinanced by EU-ESF and the Greek NSRF; the Rachadapisek Sompot Fund for a postdoctoral fellowship, Chulalongkorn University and the Chulalongkorn Academic into its 2nd Century Project Advancement Project (Thailand); and the Welch Foundation, Contract No. C-1845. 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, RosAtom, RAS, RFBR and RAEP (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEP-Center, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie program and the European Research Council and a Horizon 2020 grant, Contract No. 675440 (European Union); the Leventis Foundation; the A. P.
| Funders | Funder number |
|---|---|
| CPAN | |
| EU-ESF | |
| MSES | |
| MoER | |
| PCTI | |
| RAEP | |
| STAR | |
| ThEP-Center | |
| National Science Foundation | 1606321, 1151640, 1506168, 1506130, 1508869 |
| National Institutes of Health | |
| U.S. Department of Energy | |
| Welch Foundation | C-1845 |
| Hispanics in Philanthropy | |
| Alexander von Humboldt-Stiftung | |
| Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS) | |
| Qatar National Research Fund | |
| Ministry of Education and Science | |
| Secretaría de Educación Pública | |
| Türkiye Atom Enerjisi Kurumu | |
| Horizon 2020 Framework Programme | |
| Louisiana Academy of Sciences | |
| CERN | |
| Cosmetic Surgery Foundation | |
| Institute for the Promotion of Teaching Science and Technology | |
| Ministerstwo Obrony Narodowej | |
| Science and Technology Facilities Council | GRIDPP, ST/N000242/1 |
| European Commission | |
| European Research Council | |
| Department of Science and Technology, Ministry of Science and Technology, India | |
| Council of Scientific and Industrial Research, India | |
| Ministry of Education - Singapore | |
| Department of Atomic Energy, Government of India | |
| Science Foundation Ireland | |
| Helmholtz-Gemeinschaft | |
| Deutsche Forschungsgemeinschaft | |
| Fundação de Amparo à Pesquisa do Estado de São Paulo | |
| National Natural Science Foundation of China | |
| Research Promotion Foundation | |
| Ministerstvo Školství, Mládeže a Tělovýchovy | |
| National Science Council | |
| Fundacja na rzecz Nauki Polskiej | |
| Fundação para a Ciência e a Tecnologia | |
| Russian Foundation for Basic Research | |
| Eesti Teadusagentuur | |
| Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |
| Academy of Finland | |
| Bundesministerium für Bildung und Forschung | |
| Chinese Academy of Sciences | |
| Austrian Science Fund | |
| Fonds De La Recherche Scientifique - FNRS | |
| Russian Academy of Sciences | |
| Belgian Federal Science Policy Office | |
| Chulalongkorn University | |
| Federación Española de Enfermedades Raras | |
| Fonds Wetenschappelijk Onderzoek | |
| Agentschap voor Innovatie door Wetenschap en Technologie | |
| Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture | |
| Consejo Nacional de Ciencia y Tecnología | |
| Ministerio de Educación, Cultura y Deporte | |
| Bundesministerium für Wissenschaft, Forschung und Wirtschaft | |
| General Secretariat for Research and Technology | |
| Ministry of Business, Innovation and Employment | |
| Hungarian Scientific Research Fund | |
| Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
| Ministry of Science, ICT and Future Planning | |
| National Research Foundation of Korea | |
| Joint Institute for Nuclear Research | |
| Instituto Nazionale di Fisica Nucleare | |
| A.G. Leventis Foundation | |
| National Science and Technology Development Agency | Thailand |
| Narodowe Centrum Nauki | 2014/15/B/ST2/03998, 2012/07/E/ST2/01406, 2015/19/B/ST2/02861, 2014/14/M/ST2/00428, 2014/13/B/ST2/02543 |
| Secretaría de Educación Superior, Ciencia, Tecnología e Innovación | |
| Universiti Malaya | |
| Türkiye Bilimsel ve Teknolojik Araştirma Kurumu | |
| Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja | |
| Ministerstwo Edukacji i Nauki | |
| Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
| Ministry of Science and Technology, Taiwan | |
| National Academy of Sciences of Ukraine | |
| Centre National de la Recherche Scientifique | |
| Universidad Autónoma de San Luis Potosí | |
| Ministry of Education and Science | |
| Institute for Research in Fundamental Sciences | |
| Benemérita Universidad Autónoma de Puebla | |
| Commissariat à l'Énergie Atomique et aux Énergies Alternatives | |
| Secretaría de Estado de Investigación, Desarrollo e Innovación | |
| Horizon 2020 | 675440 |
| European Regional Development Fund | |
| State Atomic Energy Corporation ROSATOM | |
| Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional | |
| Pakistan Atomic Energy Commission | |
| State Fund for Fundamental Research of Ukraine | |
| Institut National de Physique Nucléaire et de Physique des Particules | |
| Laboratorio Nacional de Supercómputo del Sureste de Mexico |