Suchergebnisse

A search for dark matter is conducted in final states containing a photon and missing transverse momentum in proton–proton collisions at p - = 13 TeV. The data, collected during 2015–2018 by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 fb-1. No deviations from the predictions of the Standard Model are observed and 95% confidence-level upper limits between 2.45 fb and 0.5 fb are set on the visible cross section for contributions from physics beyond the Standard Model, in different ranges of the missing transverse momentum. The results are interpreted as 95% confidence-level limits in models where weakly interacting dark-matter candidates are pair-produced via an -channel axial-vector or vector mediator. Dark-matter candidates with masses up to 415 (580) GeV are excluded for axial-vector (vector) mediators, while the maximum excluded mass of the mediator is 1460 (1470) GeV. In addition, the results are expressed in terms of 95% confidence-level limits on the parameters of a model with an axion-like particle produced in association with a photon, and are used to constrain the coupling - of an axion-like particle to the electroweak gauge bosons. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; Austrian Science Fund (FWF) ; Azerbaijan National Academy of Sciences (ANAS) ; SSTC, Belarus ; National Council for Scientific and Technological Development (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, Tecnología e Innovación 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 ; NRC KI, Russian Federation ; MESTD, 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 Bern, Switzerland ; 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 ; Herakleitos, Greece ; Thales programme - EU-ESF, Greece ; Aristeia programme - EU-ESF, Greece ; 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 ; PROMETEO Programme Generalitat Valenciana, Spain ; GenT Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

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 MIZŠ, 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 Skłodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and 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; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran 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 (U.K.) and BNL (U.S.A.), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. ; This paper describes a measurement of light-by-light scattering based on Pb+Pb collision data recorded by the ATLAS experiment during Run 2 of the LHC. The study uses 2.2 nb(-1) of integrated luminosity collected in 2015 and 2018 at root sNN = 5.02TeV. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy E-T(gamma) > 2.5 GeV, pseudorapidity vertical bar eta(gamma)vertical bar 5 GeV, and with small diphoton transverse momentum and diphoton acoplanarity. The integrated and differential fiducial cross sections are measured and compared with theoretical predictions. The diphoton invariant mass distribution is used to set limits on the production of axion-like particles. This result provides the most stringent limits to date on axion-like particle production for masses in the range 6-100 GeV. Cross sections above 2 to 70 nb are excluded at the 95% CL in that mass interval. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; Austrian Science Fund (FWF) ; Azerbaijan National Academy of Sciences (ANAS) ; SSTC, Belarus ; National Council for Scientific and Technological Development (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 ; 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) ; 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 NRC KI, Russian Federation ; MESTD, 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 Bern, Switzerland 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 ; Herakleitos programme - EU-ESF, Greece ; Thales programme - EU-ESF, Greece ; Aristeia programme - EU-ESF, Greece ; 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 ; PROMETEO Programme Generalitat Valenciana, Spain ; GenT Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

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;MNiSWand NCN, Poland; FCT, Portugal; MNE/IFA, Romania; JINR;MES of Russia and NRC KI, Russian Federation; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, 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 and Technology Commission, China; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and ANR,France;DFGandAvHFoundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed 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; Göran 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. ; A search for the pair production of heavy leptons as predicted by the type-III seesaw mechanism is presented. The search uses proton-proton collision data at a centre-of-mass energy of 13TeV, corresponding to 139 fb-1 of integrated luminosity recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis focuses on the final state with two light leptons (electrons or muons) of different flavour and charge combinations, with at least two jets and large missing transverse momentum. No significant excess over the Standard Model expectation is observed. The results are translated into exclusion limits on heavy-lepton masses, and the observed lower limit on the mass of the type-III seesaw heavy leptons is 790GeV at 95% confidence level. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; Austrian Science Fund (FWF) ; Azerbaijan National Academy of Sciences (ANAS) ; SSTC, Belarus ; National Council for Scientific and Technological Development (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 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 NRC KI, Russian Federation ; MESTD, 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 Bern, Switzerland 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 ; Herakleitos programme - EU-ESF, Greece ; Thales programme - EU-ESF, Greece ; Aristeia programme - EU-ESF, Greece ; 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 ; PROMETEO Programme Generalitat Valenciana, Spain ; GenT Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

We thank CERN for the very successful operation of the LHC, as well as the support sta from our institutions without whom ATLAS could not be operated e ciently. 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 MIZ S, 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 Sk lodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co- nanced 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; G oran 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. [48]. ; A search is presented for the production of the Standard Model Higgs boson in association with a high-energy photon. With a focus on the vector-boson fusion process and the dominant Higgs boson decay into b-quark pairs, the search benefits from a large reduction of multijet background compared to more inclusive searches. Results are reported from the analysis of 132 fb(-1) of pp collision data at root s = 13 TeV collected with the ATLAS detector at the LHC. The measured Higgs boson signal yield in this final-state signature is 1.3 +/- 1.0 times the Standard Model prediction. The observed significance of the Higgs boson signal above the background is 1.3 standard deviations, compared to an expected significance of 1.0 standard deviations. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; 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 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 ; NRC KI, Russian Federation ; MESTD, 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 Bern, Switzerland ; 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) ; French National Research Agency (ANR) French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Herakleitos programme - EU-ESF ; Thales programme - EU-ESF ; Aristeia programme - EU-ESF ; 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 ; PROMETEO Programme Generalitat Valenciana, Spain ; GenT Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; The Royal Society, United Kingdom ; Leverhulme Trust

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; MESofRussia andNRCKI, 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; DOEandNSF, USA. In addition, individual groups andmembers have received support fromBCKDF, CANARIE, ComputeCanada, 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 programmes co-financed 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. [78]. ; The production cross-section of a top quark in association with a W boson is measured using proton–proton collisions at √ s = 8 TeV. The dataset corresponds to an integrated luminosity of 20.2 fb−1, and was collected in 2012 by the ATLAS detector at the Large Hadron Collider at CERN. The analysis is performed in the single-lepton channel. Events are selected by requiring one isolated lepton (electron or muon) and at least three jets. A neural network is trained to separate the tW signal from the dominant t ¯t background. The cross-section is extracted from a binned profile maximum-likelihood fit to a two-dimensional discriminant built from the neural-network output and the invariant mass of the hadronically decaying W boson. The measured crosssection is σtW = 26 ± 7 pb, in good agreement with the Standard Model expectation. ; CERN ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW ; 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) Canada Foundation for Innovation ; National Natural Science Foundation of China (NSFC) ; Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias ; Ministry of Education, Youth & Sports - Czech Republic ; MPO CR ; Czech Republic Government ; DNRF ; Danish Natural Science Research Council ; Centre National de la Recherche Scientifique (CNRS) CEA-DRF/IRFU, France ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC and 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; NWO, Netherlands ; RCN, Norway ; Ministry of Science and Higher Education, Poland NCN, Poland ; Portuguese Foundation for Science and Technology European Commission ; MNE/IFA, Romania ; Russian Federation ; Ministry of Education, Science & Technological Development, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia MIZS, Slovenia ; Spanish Government ; SRC ; Wallenberg Foundation, Sweden ; SNSF and Cantons of Bern and Geneva, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; UK Research & Innovation (UKRI) ; Science & Technology Facilities Council (STFC) ; CANARIE ComputeCanada ; Beijing Municipal Science & Technology Commission ; COST, ERC European Commission Marie Sklodowska-Curie Actions, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; European Commission ; Alexander von Humboldt Foundation ; Greek NSRF, Greece ; BSF-NSF ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Foundation CERCA Programme Generalitat de Catalunya ; PROMETEO Generalitat Valenciana ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; European Commission ; Leverhulme Trust ; NDGF (Denmark, Norway, Sweden) ; KIT/GridKA (Germany) ; INFN-CNAF (Italy) ; NL-T1 (Netherlands), PIC (Spain) ; ASGC (Taiwan) ; BNL (USA)

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; Minciencias, 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, U.K.; DOE and NSF, U.S.A. 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 programmes co-financed 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, U.K. ; This article presents a new set of proton parton distribution functions, AT-LASepWZVjet20, produced in an analysis at next-to-next-to-leading order in QCD. The new data sets considered are the measurements of W+ and W- boson and Z boson production in association with jets in pp collisions at root s = 8TeV performed by the ATLAS experiment at the LHC with integrated luminosities of 20.2 fb(-1) and 19.9 fb(-1), respectively. The analysis also considers the ATLAS measurements of differential W-+/- and Z boson production at root s = 7 TeV with an integrated luminosity of 4.6 fb(-1) and deep-inelastic-scattering data from e(+/-) p collisions at the HERA accelerator. An improved determination of the sea-quark densities at high Bjorken x is shown, while confirming a strange-quark density similar in size to the up- and down-sea-quark densities in the range x less than or similar to 0.02 found by previous ATLAS analyses. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; 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) ; Minciencias, Colombia ; 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 ; MES of Russia 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 Bern, Switzerland ; 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 ; Herakleitos programme - EU-ESF Thales Group Aristeia programme - EU-ESF 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 GenT Programme Generalitat Valenciana, Spain PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

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

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, Au CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANIstralia; BMWFW and FWF, Austria; ANAXS, Azerbaijan; SSTC, Belarus;D, Chile; CAS, MOST and NSFC, China; Minciencias, 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; MESofRussia andNRCKI, 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; DOEandNSF, USA. In addition, individual groups andmembers have received support fromBCKDF, CANARIE, ComputeCanada, 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 programmes co-financed 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), theY Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in Ref. [91]. ; Measurements of both the inclusive and differential production cross sections of a top-quark-antiquark pair in association with a Z boson (t (t) over barZ) are presented. The measurements are performed by targeting final states with three or four isolated leptons (electrons or muons) and are based on root s = 13 TeV proton-proton collision data with an integrated luminosity of 139 fb(-1), recorded from 2015 to 2018 with the ATLAS detector at the CERN Large Hadron Collider. The inclusive cross section is measured to be a sigma(t (t) over barZ)= 0.99 +/- 0.05 (stat.) +/- 0.08 (syst.) pb, in agreement with the most precise theoretical predictions. The differential measurements are presented as a function of a number of kinematic variables which probe the kinematics of the t (t) over barZ system. Both absolute and normalised differential crosssection measurements are performed at particle and parton levels for specific fiducial volumes and are compared with theoretical predictions at different levels of precision, based on a chi(2)/ndf and p value computation. Overall, good agreement is observed between the unfolded data and the predictions. ; CERN ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; 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 ; SSTC, Belarus ; 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 ; MESofRussia ; 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) ; Cantons of Bern and Geneva, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ; DOEandNSF, USA ; BCKDF, Canada ; CANARIE, Canada ; ComputeCanada, Canada ; CRC, Canada ; IVADO, Canada ; Beijing Municipal Science & Technology Commission ; COST, France ; ERC, France ; ERDF, France ; Horizon 2020 and Marie Sklodowska-Curie Actions, European Union, France ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Thales Group ; Aristeia programmes ; EU-ESF, Greece ; 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 ; GenT Programmes Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust ; BMWFW, Austria ; Austrian Science Fund (FWF) ; Azerbaijan National Academy of Sciences (ANAS) ; D, Chile ; Minciencias, Colombia

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; COLCIEN-CIAS, 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; MNiSWand NCN, Poland; FCT, Portugal; MNE/IFA, Romania; JINR; MES of Russia and NRC KI, Russian Federation; MESTD, Serbia; MSSR, Slovakia; ARRS andMIZS, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF andCantons of Bern andGeneva, 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 programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSFNSF 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), CCIN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NLT1 (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. [97]. ; The results of a search for gluino and squark pair production with the pairs decaying via the lightest charginos into a final state consisting of two W bosons, the lightest neutralinos ((chi) over tilde (0)(1)), and quarks, are presented: the signal is characterised by the presence of a single charged lepton (e(+/-) or mu(+/-)) from a W boson decay, jets, and missing transverse momentum. The analysis is performed using 139 fb(-1) of proton-proton collision data taken at a centre-of-mass energy root s = 13 delivered by the Large Hadron Collider and recorded by the ATLAS experiment. No statistically significant excess of events above the Standard Model expectation is found. Limits are set on the direct production of squarks and gluinos in simplified models. Masses of gluino (squark) up to 2.2 (1.4 ) are excluded at 95% confidence level for a light (chi) over tilde (0)(1). ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; 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 ; 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) ; Cantons of Bern andGeneva, 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 and Marie Sklodowska-Curie Actions, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Herakleitos - EU-ESF ; Thales Group ; Greek NSRF, Greece ; BSFNSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Banking Foundation, Spain ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO and GenT Programmes Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

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; Be 1/4 ing 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 programmes co-financed 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 (U.K.) and BNL (U.S.A.), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. [48]. ; The ATLAS experiment at the Large Hadron Collider (LHC) employs a trigger system consisting of a first-level hardware trigger (L1) and a software-based high-level trigger. The L1 muon trigger system selects muon candidates, assigns them to the correct LHC bunch crossing and classifies them into one of six transverse-momentum threshold classes. The L1 muon trigger system uses resistive-plate chambers (RPCs) to generate the muon-induced trigger signals in the central (barrel) region of the ATLAS detector. The ATLAS RPCs are arranged in six concentric layers and operate in a toroidal magnetic field with a bending power of 1.5 to 5.5 Tm. The RPC detector consists of about 3700 gas volumes with a total surface area of more than 4000 m(2). This paper reports on the performance of the RPC detector and L1 muon barrel trigger using 60.8 fb(-1) of proton-proton collision data recorded by the ATLAS experiment in 2018 at a centre-of-mass energy of 13 TeV. Detector and trigger performance are studied using Z boson decays into a muon pair. Measurements of the RPC detector response, efficiency, and time resolution are reported. Measurements of the L1 muon barrel trigger efficiencies and rates are presented, along with measurements of the properties of the selected sample of muon candidates. Measurements of the RPC currents, counting rates and mean avalanche charge are performed using zero-bias collisions. Finally, RPC detector response and efficiency are studied at different high voltage and front-end discriminator threshold settings in order to extrapolate detector response to the higher luminosity expected for the High Luminosity LHC. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW ; 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 ; MSMT CR, Czech Republi 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 ; MES of Russia 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) Cantons of Bern and 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) ; United States of America ; European Commission ; Greek NSRF, Greece ; BSF-NSF ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Foundation CERCA Programme Generalitat de Catalunya PROMETEO and GenT Programmes Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; European Commission ; Leverhulme Trust

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; Minciencias, 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, USA. 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; BSFNSF 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), CCIN2P3 (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. [106]. ; A search for pair production of bottom squarks in events with hadronically decaying t-leptons, b-tagged jets, and large missing transverse momentum is presented. The analyzed dataset is based on proton-proton collisions at root s = 13 TeV delivered by the Large Hadron Collider and recorded by the ATLAS detector from 2015 to 2018, and corresponds to an integrated luminosity of 139 fb(-1). The observed data are compatible with the expected Standard Model background. Results are interpreted in a simplified model where each bottom squark is assumed to decay into the second-lightest neutralino (chi) over tilde (0)(2) and a bottom quark, with (chi) over tilde (0)(2) decaying into a Higgs boson and the lightest neutralino (chi) over tilde1(0). The search focuses on final states where at least one Higgs boson decays into a pair of hadronically decaying t-leptons. This allows the acceptance and thus the sensitivity to be significantly improved relative to the previous results at low masses of the (chi) over tilde (0)(2), where bottom-squark masses up to 850 GeV are excluded at the 95% confidence level, assuming a mass difference of 130 GeV between (chi) over tilde (0)(2) and (chi) over tilde (0)(1). Model-independent upper limits are also set on the cross section of processes beyond the Standard Model. ; CERN ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW ; 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) ; Canada Foundation for Innovation ; MOST ; National Natural Science Foundation of China (NSFC) ; Ministry of Education, Youth & Sports - Czech Republic ; MPO CR ; Czech Republic Government ; DNRF Danish Natural Science Research Council ; Centre National de la Recherche Scientifique (CNRS) ; CEA-DRF/IRFU, France ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC and Hong Kong SAR, China ; ISF and 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; NWO ; RCN, Norway ; Ministry of Science and Higher Education, Poland ; NCN, Poland ; Portuguese Foundation for Science and Technology ; European Commission ; MNE/IFA, Romania ; Ministry of Education, Science & Technological Development, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; Spanish Government ; Wallenberg Foundation, Sweden ; Swiss National Science Foundation (SNSF) ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; UK Research & Innovation (UKRI) ; Science & Technology Facilities Council (STFC) ; National Science Foundation (NSF) ; BCKDF ; CANARIE ; Beijing Municipal Science & Technology Commission ; COST, ERC ; European Commission ; Marie Sklodowska-Curie Actions, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; European Commission ; Alexander von Humboldt Foundation ; Thales Group ; European Commission ; Greek NSRF, Greece ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Foundation ; CERCA Programme Generalitat de Catalunya ; PROMETEO ; Generalitat Valenciana ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; European Commission ; Leverhulme Trust ; NDGF (Denmark, Norway, Sweden) ; CCIN2P3 (France) ; KIT/GridKA (Germany) ; INFN-CNAF (Italy) ; NL-T1 (Netherlands), PIC (Spain) ; ASGC (Taiwan) ; RAL (UK) ; BNL (USA) 106

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; Minciencias, 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 programmes co-financed 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. ; A search for dark-matter particles in events with large missing transverse momentum and a Higgs boson candidate decaying into two photons is reported. The search uses 139 fb(-1) of proton-proton collision data collected at root s = 13 TeV with the ATLAS detector at the CERN LHC between 2015 and 2018. No significant excess of events over the Standard Model predictions is observed. The results are interpreted by extracting limits on three simplified models that include either vector or pseudoscalar mediators and predict a final state with a pair of dark-matter candidates and a Higgs boson decaying into two photons. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; 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) ; Minciencias, Colombia ; 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) ; 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 ; MES of Russia ; 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 Bern, Switzerland ; 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 ; European Cooperation in Science and Technology (COST) ; European Research Council (ERC) European Commission European Commission Horizon 2020 Marie Sklodowska-Curie Actions European Commission ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Herakleitos, Greece ; Aristeia programmes - EU-ESF, Greece ; Greek NSRF, Greece ; Thales Group ; BSF-NSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Banking Foundation, Spain ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO, Spain ; GenT Programmes Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

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; Minciencias, 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; GSRI, 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; DSI/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 and CRC, Canada; 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 programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and GIF, Israel; Norwegian Financial Mechanism 2014-2021, Norway; 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), NLT1 (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.[52]. ; Searches for new resonances in the diphoton final state, with spin 0 as predicted by theories with an extended Higgs sector and with spin 2 using a warped extra-dimension benchmark model, are presented using 139 fb(-1) of root s = 13 TeV pp collision data collected by the ATLAS experiment at the LHC. No significant deviation from the Standard Model is observed and upper limits are placed on the production cross-section times branching ratio to two photons as a function of the resonance mass. ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; 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) ; Minciencias, Colombia ; 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 ; GSRI, Greece ; 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) ; 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 ; NRC KI, Russian Federation ; Ministry of Education, Science & Technological Development, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia MIZS, Slovenia ; DSI/NRF, South Africa ; Spanish Government ; SRC, Sweden Wallenberg Foundation, Sweden ; SERI, Switzerland Swiss National Science Foundation (SNSF) Canton of Bern, Switzerland 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 ; 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 ; Herakleitos programme - EU-ESF, Greece Thales Group Aristeia programme - EU-ESF, Greece Greek NSRF, Greece ; BSF-NSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; Norwegian Financial Mechanism 2014-2021, Norway ; La Caixa Banking Foundation, Spain CERCA Programme Generalitat de Catalunya, Spain PROMETEO Programme Generalitat Valenciana, Spain GenT Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust

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 programmes co-financed 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. [35]. ; The total cross section and differential cross sections for the production of B-c(+/-) mesons, times their branching fraction to J/psi pi(+/-), are measured relative to those for the production of B-+/- mesons, times their branching fraction to J/psi K-+/-. The data used for this study correspond to an integrated luminosity of 20.3 fb(-1) of pp collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of root s = 8 TeV. The measurement is performed differentially in bins of transverse momentum p(T) for 13 GeV 22 GeV and in bins of rapidity y for vertical bar y vertical bar 13 GeV and vertical bar y vertical bar < 2.3 is (0.34 +/- 0.04(stat) (+0.06)(-0.02 sys) +/- 0.01(lifetime))%. The differential measurements suggest that the production cross section of the B-c(+/-) decreases faster with p(T) than the production cross section of the B-+/-, while no significant dependence on rapidity is observed. ; CERN ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW, Austria ; 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) ; Canada Foundation for Innovation ; National Natural Science Foundation of China (NSFC) ; Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias ; Ministry of Education, Youth & Sports - Czech Republic ; MPO CR ; Czech Republic Government ; DNRF ; Danish Natural Science Research Council ; Centre National de la Recherche Scientifique (CNRS) ; CEA-DRF/IRFU, France ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC and 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) ; Japan Society for the Promotion of Science ; CNRST, Morocco; NWO, Netherlands ; RCN, Norway ; Ministry of Science and Higher Education, Poland ; NCN, Poland ; Portuguese Foundation for Science and Technology European Commission ; MNE/IFA, Romania ; Ministry of Education, Science & Technological Development, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; Spanish Government ; SRC ; Wallenberg Foundation, Sweden ; Swiss National Science Foundation (SNSF) ; 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 ; CANARIE ; Beijing Municipal Science & Technology Commission ; COST, ERC ; European Commission ; Marie Sklodowska-Curie Actions, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; European Commission ; Alexander von Humboldt Foundation ; Greek NSRF, Greece ; BSF-NSF ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Foundation ; CERCA Programme Generalitat de Catalunya PROMETEO Generalitat Valenciana ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; European Commission ; Leverhulme Trust ; NDGF (Denmark, Norway, Sweden) ; KIT/GridKA (Germany) ; INFN-CNAF (Italy) ; NL-T1 (Netherlands), PIC (Spain) ; ASGC (Taiwan) ; BNL (USA)

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, Azerba¼an; 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 MIZŠ, 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; Be¼ing Municipal Science & Technology Commission, China; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and 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; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO TEO and GenT Programmes Generalitat Valenciana, Spain; Göran 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 (U.K.) and BNL (U.S.A.), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. [52]. ; The ATLAS Fast TracKer (FTK) was designed to provide full tracking for the ATLAS high-level trigger by using pattern recognition based on Associative Memory (AM) chips and fitting in high-speed field programmable gate arrays. The tracks found by the FTK are based on inputs from all modules of the pixel and silicon microstrip trackers. The as-built FTK system and components are described, as is the online software used to control them while running in the ATLAS data acquisition system. Also described is the simulation of the FTK hardware and the optimization of the AM pattern banks. An optimization for long-lived particles with large impact parameter values is included. A test of the FTK system with the data playback facility that allowed the FTK to be commissioned during the shutdown between Run 2 and Run 3 of the LHC is reported. The resulting tracks from part of the FTK system covering a limited η-ϕ region of the detector are compared with the output from the FTK simulation. It is shown that FTK performance is in good agreement with the simulation. ; 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 MIZŠ, 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 ; BCKDF ; CANARIE, Compute Canada, CRC and IVADO, Canada ; Bejiing Municipal Science & Technology Commission, China ; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union ; Investissements d'Avenir Labex, Investissements d'Avenir Idex and 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 ; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain ; Göran Gustafssons Stiftelse, Sweden ; The Royal Society and Leverhulme Trust, United Kingdom