Exclusive dimuon production in ultraperipheral Pb + Pb collisions at √sNN = 5.02 TeV with ATLAS

Open Access

Abstract

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; ANID, Chile; CAS, MOST, and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR, and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC and 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; JINR, MES of Russia, and NRC KI, Russian Federation; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZS, Slovenia; DST/NRF, South Africa; MICINN, 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, Compute Canada, CRC, and IVADO, Canada; Beijing Municipal Science & Technology Commission, China; COST, ERC, ERDF, Horizon 2020, and Marie Sklodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex, and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales, and Aristeia programs cofinanced by EU-ESF and the Greek NSRF, Greece; BSF-NSF and GIF, Israel; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya, and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Goran Gustafssons Stiftelse, Sweden; 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. [60]. ; Exclusive dimuon production in ultraperipheral collisions (UPC), resulting from photon-photon interactions in the strong electromagnetic fields of colliding high-energy lead nuclei, PbPb(gamma gamma) -> mu(+) mu(-) (Pb-(*Pb-)(()*())), is studied using L-int = 0.48 nb(-1) of root S-NN = 5.02 TeV lead-lead collision data at the LHC with the ATLAS detector. Dimuon pairs are measured in the fiducial region p(T,mu) > 4 GeV, vertical bar eta(mu)vertical bar 10 GeV, and p(T,mu mu) mu(+) mu(-) process in the fiducial volume is measured to be sigma(mu mu)(fid) = 34.1 +0.3(stat.)+0.7(syst.) mu b. Generally good agreement is found with calculations from STARlight, which incorporate the leading-order Breit-Wheeler process with no final-state effects, albeit differences between the measurements and theoretical expectations are observed. In particular, the measured cross sections at larger vertical bar y(mu mu)vertical bar are found to be about 10-20% larger in data than in the calculations, suggesting the presence of larger fluxes of photons in the initial state. Modification of the dimuon cross sections in the presence of forward and/or backward neutron production is also studied and is found to be associated with a harder incoming photon spectrum, consistent with expectations. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; Austrian Science Fund (FWF) ; Azerbaijan National Academy of Sciences (ANAS) ; SSTC, Belarus ; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) ; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) ; Natural Sciences and Engineering Research Council of Canada (NSERC) ; NRC, Canada ; Canada Foundation for Innovation ; CERN ; ANID, Chile ; Chinese Academy of Sciences ; Ministry of Science and Technology, China ; National Natural Science Foundation of China (NSFC) ; Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias ; Ministry of Education, Youth & Sports - Czech Republic Czech Republic Government ; Czech Republic Government ; DNRF, Denmark ; Danish Natural Science Research Council ; Centre National de la Recherche Scientifique (CNRS) ; CEA-DRF/IRFU, France ; SRNSFG, Georgia ; Federal Ministry of Education & Research (BMBF) ; HGF, Germany ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC, China ; Hong Kong SAR, China ; Israel Science Foundation ; Benoziyo Center, Israel ; Istituto Nazionale di Fisica Nucleare (INFN) ; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) ; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science ; CNRST, Morocco ; Netherlands Organization for Scientific Research (NWO) Netherlands Government ; RCN, Norway ; Ministry of Science and Higher Education, Poland ; NCN, Poland ; Portuguese Foundation for Science and Technology European Commission ; MNE/IFA, Romania ; JINR, Russian Federation ; Russian Federation ; NRC KI, Russian Federation ; Ministry of Education, Science & Technological Development, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; Spanish Government ; SRC, Sweden ; Wallenberg Foundation, Sweden ; SERI, Switzerland ; Swiss National Science Foundation (SNSF) ; Canton of Geneva, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; IVADO, Canada ; Beijing Municipal Science & Technology Commission ; COST, European Union ; European Research Council (ERC) ; ERDF, European Union ; Horizon 2020, European Union ; Marie Sklodowska-Curie Actions, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Greek NSRF, Greece ; BSF-NSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Banking Foundation, Spain ; CERCA Programme Generalitat de Catalunya, Spain ; Goran Gustafssons Stiftelse, Sweden ; The Royal Society, United Kingdom ; Leverhulme Trust ; BMWFW, Austria ; Canton of Bern, Switzerland ; French National Research Agency (ANR) ; Herakleitos program - EU-ESF ; Thales Group ; Aristeia program - EU-ESF ; PROMETEO Programme Generalitat Valenciana, Spain ; GenT Programme Generalitat Valenciana, Spain