First measurement of quarkonium polarization in nuclear collisions at the LHC
ALICE Collaboration
(2021) Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, volume 815
(Article)
Abstract
The polarization of inclusive J/ψ and ϒ(1S) produced in Pb–Pb collisions at √sNN=5.02 TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region 2.5<y<4 and measuring the polar and azimuthal angular
... read more
distributions of the muons. The polarization parameters λθ, λϕ and λθϕ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval 2<pT<10 GeV/c and pT<15 GeV/c for the J/ψ and ϒ(1S), respectively. The polarization parameters for the J/ψ are found to be compatible with zero, within a maximum of about two standard deviations at low pT, for both reference frames and over the whole pT range. The values are compared with the corresponding results obtained for pp collisions at √s=7 and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for ϒ(1S) production in Pb–Pb collisions are also consistent with zero.
show less
Download/Full Text
Keywords: Nuclear and High Energy Physics
ISSN: 0370-2693
Publisher: Elsevier
Note: Funding Information: The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable contributions to the construction of the experiment and the CERN accelerator teams for the outstanding performance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources and support provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration. The ALICE Collaboration acknowledges the following funding agencies for their support in building and running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation (ANSL) , State Committee of Science and World Federation of Scientists (WFS) , Armenia; Austrian Academy of Sciences , Austrian Science Fund (FWF): [ M 2467-N36 ] and Österreichische Nationalstiftung für Forschung, Technologie und Entwicklung , Austria; Ministry of Communications and High Technologies, National Nuclear Research Center , Azerbaijan; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (Finep), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Universidade Federal do Rio Grande do Sul (UFRGS), Brazil; Ministry of Education of China (MOEC), Ministry of Science & Technology of China (MSTC) and National Natural Science Foundation of China (NSFC), China; Ministry of Science and Education and Croatian Science Foundation , Croatia; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN) , Cubaenergía , Cuba; Ministry of Education, Youth and Sports of the Czech Republic , Czech Republic; The Danish Council for Independent Research | Natural Sciences , the Villum Fonden and Danish National Research Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP) , Finland; Commissariat à l'Énergie Atomique (CEA) and Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) and Centre National de la Recherche Scientifique (CNRS), France; Bundesministerium für Bildung und Forschung (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung GmbH , Germany; General Secretariat for Research and Technology , Ministry of Education, Research and Religions , Greece; National Research, Development and Innovation Office , Hungary; Department of Atomic Energy, Government of India (DAE), Department of Science and Technology, Government of India (DST) , University Grants Commission, Government of India (UGC) and Council of Scientific and Industrial Research ( CSIR ), India; Indonesian Institute of Science , Indonesia; Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucleare (INFN) , Italy; Institute for Innovative Science and Technology, Nagasaki Institute of Applied Science (IIST) , Japanese Ministry of Education, Culture, Sports, Science and Technology ( MEXT ) and Japan Society for the Promotion of Science (JSPS) KAKENHI, Japan; Consejo Nacional de Ciencia (CONACYT) y Tecnología , through Fondo de Cooperación Internacional en Ciencia y Tecnología (FONCICYT) and Dirección General de Asuntos del Personal Academico (DGAPA) , Mexico; Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands; The Research Council of Norway , Norway; Commission on Science and Technology for Sustainable Development in the South (COMSATS) , Pakistan; Pontificia Universidad Católica del Perú , Peru; Ministry of Science and Higher Education , National Science Centre and WUT ID-UB , Poland; Korea Institute of Science and Technology Information and National Research Foundation of Korea (NRF), Republic of Korea; Ministry of Education and Scientific Research, Institute of Atomic Physics and Ministry of Research and Innovation and Institute of Atomic Physics , Romania; Joint Institute for Nuclear Research (JINR), Ministry of Education and Science of the Russian Federation , National Research Centre Kurchatov Institute , Russian Science Foundation and Russian Foundation for Basic Research , Russia; Ministry of Education, Science, Research and Sport of the Slovak Republic , Slovakia; National Research Foundation of South Africa , South Africa; Swedish Research Council (VR) and Knut & Alice Wallenberg Foundation (KAW), Sweden; European Organization for Nuclear Research , Switzerland; Suranaree University of Technology (SUT), National Science and Technology Development Agency (NSDTA) and Office of the Higher Education Commission under NRU project of Thailand, Thailand; Turkish Atomic Energy Agency ( TAEK ), Turkey; National Academy of Sciences of Ukraine , Ukraine; Science and Technology Facilities Council (STFC), United Kingdom; National Science Foundation of the United States of America ( NSF ) and United States Department of Energy , Office of Nuclear Physics (DOE NP), United States of America. Publisher Copyright: © 2021 The Author(s) Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
(Peer reviewed)
