The dynamics of isolated-photon plus two-jet production in pp collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset corresponding to an integrated luminosity of 36.1 fb−1. Cross sections are measured as functions of a variety of observables, including angular correlations and invariant masses of the objects in the final state, γ+jet+jet. Measurements are also performed in phase-space regions enriched in each of the two underlying physical mechanisms, namely direct and fragmentation processes. The measurements cover the range of photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level plus parton-shower predictions from SHERPA and PYTHIA as well as the next-to-leading-order QCD predictions from SHERPA are compared with the measurements. The next-to-leading-order QCD predictions describe the data adequately in shape and normalisation except for regions of phase space such as those with high values of the invariant mass or rapidity separation of the two jets, where the predictions overestimate the data. ; We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; FWF, BMWFW, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq, FAPESP, Brazil; NSERC, CFI, NRC, Canada; CERN, CERN; CONICYT, Chile; CAS, NSFC, MOST, China; COLCIENCIAS, Colombia; VSC CR, MSMT CR, MPO CR, Czech Republic; DNSRC, DNRF, Denmark; IN2P3-CNRS, CEA-DRF/IRFU, France; SRNSFG, Georgia; MPG, HGF, BMBF, Germany; GSRT, Greece; RGC, Hong Kong SAR, Hong Kong China; Benoziyo Center, ISF, Israel; INFN, Italy; JSPS, MEXT, Japan; JINR, JINR; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MNiSW, NCN, Poland; FCT, Portugal; MNE/IFA, Romania; NRC KI, MES of Russia, Russia Federation; MESTD, Serbia; MSSR, Slovakia; ARRS, MIZ S, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC, Wallenberg Foundation, Sweden; Cantons of Bern and Geneva, SNSF, SERI, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE, NSF, United states of America. In addition, individual groups and members have received support from CRC, Compute Canada, Canarie, BCKDF, Canada; Marie Sk lodowska-Curie, COST, ERDF, ERC, Horizon 2020, European Union; ANR, Investissements d'Avenir Labex and Idex, France; AvH, DFG, Germany; Herakleitos, Thales and Aristeia programmes co- nanced by EU-ESF and the Greek NSRF, Greece; BSF-NSF, GIF, Israel; PROMETEO Programme Generalitat Valenciana, CERCA Generalitat de Catalunya, Spain; Leverhulme Trust, The Royal Society, United Kingdom.
A search for new resonances decaying into a pair of jets is reported using the dataset of proton-proton collisions recorded at s√=13 TeV with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb−1. The distribution of the invariant mass of the two leading jets is examined for local excesses above a data-derived estimate of the Standard Model background. In addition to an inclusive dijet search, events with jets identified as containing b-hadrons are examined specifically. No significant excess of events above the smoothly falling background spectra is observed. The results are used to set cross-section upper limits at 95% confidence level on a range of new physics scenarios. Model-independent limits on Gaussian-shaped signals are also reported. The analysis looking at jets containing b-hadrons benefits from improvements in the jet flavour identification at high transverse momentum, which increases its sensitivity relative to the previous analysis beyond that expected from the higher integrated luminosity. ; 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; CONICYT, 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; MES of Russia and NRC KI, Russia Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZS, Slovenia; DST/NRF, South Africa; MINECO, 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; ERC, ERDF, Horizon 2020, Marie Sklodowska-Curie Actions and COST, 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; CERCA Programme Generalitat de Catalunya and PROMETEO Programme Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom.
A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of s√ = 13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015-2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full dataset are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV. ; 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; CONICYT, 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; MES of Russia and NRC KI, Russia Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC andWallenberg 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; ERC, ERDF, Horizon 2020, Marie Skłodowska-Curie Actions and COST, 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; CERCA Programme Generalitat de Catalunya and PROMETEO Programme Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom.
A search for dijet resonances in events with at least one isolated charged lepton is performed using 139 fb(-1) of root s = 13 TeV proton-proton collision data recorded by the ATLAS detector at the LHC. The dijet invariant-mass (m(jj)) distribution constructed from events with at least one isolated electron or muon is searched in the region 0.22 < m(jj) < 6.3 TeV for excesses above a smoothly falling background from Standard Model processes. Triggering based on the presence of a lepton in the event reduces limitations imposed by minimum transverse momentum thresholds for triggering on jets. This approach allows smaller dijet invariant masses to be probed than in inclusive dijet searches, targeting a variety of new-physics models, for example ones in which a new state is produced in association with a leptonically decaying W or Z boson. No statistically significant deviation from the Standard Model background hypothesis is found. Limits on contributions from generic Gaussian signals with widths ranging from that determined by the detector resolution up to 15% of the resonance mass are obtained for dijet invariant masses ranging from 0.25 TeV to 6 TeV. Limits are set also in the context of several scenarios beyond the Standard Model, such as the Sequential Standard Model, a technicolor model, a charged Higgs boson model and a simplified Dark Matter model. ; 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 ; NRC, Canada ; Canada Foundation for Innovation ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; RGC, China ; Hong Kong SAR, China ; Israel Science Foundation ; Benoziyo Center, Israel ; Istituto Nazionale di Fisica Nucleare (INFN)v ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; 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 ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; Horizon 2020, European Union ; COST, 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 ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme 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; CONICYT, 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; MES of Russia and NRC KI, Russia Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZS, Slovenia; DST/NRF, South Africa; MINECO, 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; ERC, ERDF, Horizon 2020, Marie Sklodowska-Curie Actions and COST, 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; CERCA Programme Generalitat de Catalunya and PROMETEO Programme Generalitat Valenciana, Spain; Goran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom. ; The factor of four increase in the LHC luminosity, from 0.5 × 1034 cm−2s−1 to 2.0 × 1034cm−2s−1, and the corresponding increase in pile-up collisions during the 2015–2018 data-taking period, presented a challenge for the ATLAS trigger, particularly for those algorithms that select events with missing transverse momentum. The output data rate at fixed threshold typically increases exponentially with the number of pile-up collisions, so the legacy algorithms from previous LHC data-taking periods had to be tuned and new approaches developed to maintain the high trigger efficiency achieved in earlier operations. A study of the trigger performance and comparisons with simulations show that these changes resulted in event selection efficiencies of > 98% for this period, meeting and in some cases exceeding the performance of similar triggers in earlier run periods, while at the same time keeping the necessary bandwidth within acceptable limits. ; 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 ; Canada Foundation for Innovation ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC 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 ; RCN, Norway ; Ministry of Science and Higher Education, Poland ; NCN, Poland ; Portuguese Foundation for Science and Technology ; MNE/IFA, Romania ; NRC KI, Russia Federation ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; MINECO, Spain ; SRC, Sweden ; Wallenberg Foundation, Sweden ; Cantons of Bern and Geneva, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; CRC, Canada ; European Research Council (ERC) ; European Union (EU) ; 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 ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust ; NRC Canada ; CERN ; Chinese Academy of Sciences ; Ministry of Science and Technology, China ; SRNSFG, Georgia ; HGF Germany ; Hong Kong SAR, China ; Netherlands Organization for Scientific Research (NWO) ; Netherlands Government ; MES of Russia ; JINR ; DST/NRF, South Africa ; SERI Switzerland ; Swiss National Science Foundation (SNSF) ; Compute Canada Canada ; Horizon 2020 ; Marie Sklodowska-Curie Actions ; European Cooperation in Science and Technology (COST) ; EU-ESF Greece
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; CONICYT, 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; MES of Russia and NRC KI, Russia Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZ~ S, Slovenia; DST/NRF, South Africa; MINECO, 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; ERC, ERDF, Horizon 2020, Marie Sklodowska-Curie Actions and COST, 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; CERCA Programme Generalitat de Catalunya and PROMETEO Programme 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. ; Single top-quark production in association with a Z boson, where the Z boson decays to a pair of charged leptons, is measured in the trilepton channel. The proton-proton collision data collected by the ATLAS experiment from 2015 to 2018 at a centre-of-mass energy of 13 TeV are used, corresponding to an integrated luminosity of 139 fb−1. Events containing three isolated charged leptons (electrons or muons) and two or three jets, one of which is identified as containing a b-hadron, are selected. The main backgrounds are from tt¯Z and diboson production. Neural networks are used to improve the background rejection and extract the signal. The measured cross-section for tℓ+ℓ−q production, including non-resonant dilepton pairs with mℓ+ℓ− > 30 GeV, is 97 ± 13 (stat.) ± 7 (syst.) fb, consistent with the Standard Model prediction. ; 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 ; NRC, Canada ; Canada Foundation for Innovation ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; 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 ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; Horizon 2020, European Union ; COST, 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 ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust
Inclusive and di erential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb(-1). The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13TeV. The measurements are performed in a ducial volume de ned at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The ducial cross-section is measured to be 39:6 (+2:7-2:3) fb. Di erential cross-sections as functions of several observables are compared with state-ofthe- art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and angular separations between the two leptons in the event. All measurements are in agreement with the predictions from the Standard Model ; 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 ; Canada Foundation for Innovation ; NRC, Canada ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; SRC, Sweden ; Wallenberg Foundation, Sweden ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; European Union (EU) ; Horizon 2020, European Union ; COST, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Herakleitos programme - EU-ESF, Greece ; Aristeia programme - EU-ESF, Greece ; Thales programme - EU-ESF, Greece ; Thales programme - EU-ESF, Greece ; Thales programme - EU-ESF, Greece ; German-Israeli Foundation for Scientific Research and Development ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust
This paper presents a measurement of the production cross-section of aZboson in association withb-jets, in proton-proton collisions at root s = 13 TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 35.6 fb(-1). Inclusive and differential cross-sections are measured for events containing aZboson decaying into electrons or muons and produced in association with at least one or at least two b-jets with transverse momentum p(T)>20 GeV and rapidity vertical bar y vertical bar <2.5. Predictions from several Monte Carlo generators based on leading-order (LO) or next-to-leading-order (NLO) matrix elements interfaced with a parton-shower simulation and testing different flavour schemes for the choice of initial-state partons are compared with measured cross-sections. The 5-flavour number scheme predictions at NLO accuracy agree better with data than 4-flavour number scheme ones. The 4-flavour number scheme predictions underestimate data in events with at least one b-jet. ; 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 ; Canada Foundation for Innovation ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC, 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 ; RCN, Norway ; Ministry of Science and Higher Education, Poland ; NCN, Poland ; Portuguese Foundation for Science and Technology ; MNE/IFA, Romania ; NRC KI, Russia Federation ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; MINECO, Spain ; SRC, Sweden ; Wallenberg Foundation, Sweden ; SERI, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; European Union (EU) ; French National Research Agency (ANR) ; 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 ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust ; NRC, Canada ; CERN ; Chinese Academy of Sciences ; Ministry of Science and Technology, China ; HGF, Germany ; SRNSFG, Georgia ; Hong Kong SAR, China ; Netherlands Organization for Scientific Research (NWO) Netherlands Government ; MES of Russia, Russia Federation ; JINR ; DST/NRF, South Africa ; Swiss National Science Foundation (SNSF) ; Cantons of Bern and Geneva, Switzerland ; Compute Canada, Canada ; Horizon 2020 ; Marie Sklodowska-Curie Actions ; COST, European Union ; French National Research Agency (ANR) ; Herakleitos ; Thales ; Aristeia programmes ; EU-ESF, Greece
The inclusive top quark pair (t ¯t) production cross-section σt ¯t has been measured in proton–proton collisions at √ s = 13 TeV, using 36.1fb−1 of data collected in 2015–2016 by the ATLAS experiment at the LHC. Using events with an opposite-charge eμ pair and b-tagged jets, the cross-section is measured to be: σt ¯t = 826.4 ± 3.6 (stat) ± 11.5 (syst) ± 15.7 (lumi) ±1.9 (beam) pb, where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the LHC beam energy, giving a total uncertainty of 2.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. It is used to determine the top quark pole mass via the dependence of the predicted cross-section on mpole t , giving mpole t = 173.1+2.0 −2.1 GeV. It is also combined with measurements at √ s = 7 TeV and √ s = 8 TeV to derive ratios and double ratios of t ¯t and Z cross-sections at different energies. The same event sample is used to measure absolute and normalised differential cross-sections as functions of singlelepton and dilepton kinematic variables, and the results are compared with predictions from various Monte Carlo event generators. ; 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 ; Canada Foundation for Innovation ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC, 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 ; DNRF, Denmark ; CNRST, Morocco ; RCN, Norway ; Ministry of Science and Higher Education, Poland ; NCN, Poland ; Portuguese Foundation for Science and Technology ; MNE/IFA, Romania ; NRC KI, Russia Federation ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; MINECO, Spain ; SRC, Sweden ; Wallenberg Foundation, Sweden ; SNSF Geneva, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; CRC, Canada ; European Research Council (ERC) ; European Union (EU) ; European Union (EU) ; French National Research Agency (ANR) ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Greek NSRF, Greece ; BSF-NSF ; German-Israeli Foundation for Scientific Research and Development ; CERCA Programme Generalitat de Catalunya ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust ; NRC, Canada ; CERN ; Chinese Academy of Sciences ; Ministry of Science and Technology, China ; SRNSFG, Georgia ; HGF, Germany ; Hong Kong SAR, China ; Netherlands Organization for Scientific Research (NWO) Netherlands Government ; MES of Russia ; JINR ; DST/NRF, South Africa ; SERI Geneva, Switzerland ; Cantons of Bern and Geneva, Switzerland ; Compute Canada, Canada ; Horizon 2020 ; Marie Sklodowska-Curie Actions ; European Cooperation in Science and Technology (COST) ; Alexander von Humboldt Foundation ; European Union (EU)
Several models of physics beyond the Standard Model predict the existence of dark photons, light neutral particles decaying into collimated leptons or light hadrons. This paper presents a search for long-lived dark photons produced from the decay of a Higgs boson or a heavy scalar boson and decaying into displaced collimated StandardModel fermions. The search uses data corresponding to an integrated luminosity of 36.1 fb−1 collected in proton– proton collisions at √ s = 13 TeV recorded in 2015–2016 with the ATLAS detector at the Large Hadron Collider. The observed number of events is consistent with the expected background, and limits on the production cross section times branching fraction as a function of the proper decay length of the dark photon are reported.Across section times branching fraction above 4 pb is excluded for a Higgs boson decaying into two dark photons for dark-photon decay lengths between 1.5 mm and 307 mm. ; 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 ; NRC, Canada ; Canada Foundation for Innovation ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; IN2P3-CNRS, CEADRF/IRFU, France ; SRNSFG, Georgia ; Federal Ministry of Education & Research (BMBF) ; HGF, Germany ; Max Planck Society ; Greek Ministry of Development-GSRT ; Hong Kong Research Grants Council ; 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 ; MNE/IFA, Romania ; Russian Federation ; NRC KI, Russian Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; 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 ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; CRC, Canada ; Compute Canada, Canada ; COST, European Union ; European Union (EU) European Research Council (ERC) ; Horizon 2020, European Union ; European Union (EU) ; 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 ; CERCA Programme Generalitat de Catalunya, Spain ; Royal Society of London ; Leverhulme Trust
A search for supersymmetric partners of gluons and quarks is presented, involving signatures with jets and either two isolated leptons (electrons or muons) with the same electric charge, or at least three isolated leptons. A data sample of proton-proton collisions at p s = 13TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to a total integrated luminosity of 139 fb(-1), is used for the search. No signi cant excess over the Standard Model expectation is observed. The results are interpreted in simpli ed supersymmetric models featuring both R-parity conservation and R-parity violation, raising the exclusion limits beyond those of previous ATLAS searches to 1600 GeV for gluino masses and 750 GeV for bottom and top squark masses in these scenarios. ; 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 ; Canada Foundation for Innovation ; NRC, Canada ; National Natural Science Foundation of China (NSFC) ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; Chinese Academy of Sciences ; Ministry of Science and Technology, China ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; SRC, Sweden ; Wallenberg Foundation, 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 ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; Horizon 2020, European Union ; COST, European Union ; French National Research Agency (ANR) ; Herakleitos programme ; Thales programme ; Aristeia programme ; European Union (EU) ; Greek NSRF, Greece ; BSF-NSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; G~oran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust
A search for a chargino-neutralino pair decaying via the 125 GeV Higgs boson into photons is presented. The study is based on the data collected between 2015 and 2018 with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb(-1) of pp collisions at a centre-of-mass energy of 13 TeV. No significant excess over the expected background is observed. Upper limits at 95% confidence level for a massless (chi) over tilde (0)(1) are set on several electroweakino production cross-sections and the visible cross-section for beyond the Standard Model processes. In the context of simplified supersymmetric models, 95% confidence-level limits of up to 310 GeV in m((chi) over tilde (+/-)(1)/(chi) over tilde (0)(2)), where m((chi) over tilde (0)(1)) = 0.5 GeV, are set. Limits at 95% confidence level are also set on the (chi) over tilde (+/-)(1)(chi) over tilde (0)(2) cross-section in the mass plane of m((chi) over tilde (+/-)(1)/(chi) over tilde (0)(2)) and m((chi) over tilde (0)(1)), and on scenarios with gravitino as the lightest supersymmetric particle. Upper limits at the 95% confidence-level are set on the higgsino production cross-section. Higgsino masses below 380 GeV are excluded for the case of the higgsino fully decaying into a Higgs boson and a gravitino. ; 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 ; NRC, Canada ; Canada Foundation for Innovation ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; 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 ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; Horizon 2020, European Union ; COST, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Herakleitos program - EU-ESF, Greece ; Thales program - EU-ESF, Greece ; Aristeia program - EU-ESF, Greece ; Greek NSRF, Greece ; BSF-NSF, Israel ; German-Israeli Foundation for Scientific Research and Development ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust
A search for new-physics resonances decaying into a lepton and a jet performed by the ATLAS experiment is presented. Scalar leptoquarks pair-produced in pp collisions at p s = 13TeV at the Large Hadron Collider are considered using an integrated luminosity of 139 fb-1, corresponding to the full Run 2 dataset. They are searched for in events with two electrons or two muons and two or more jets, including jets identi ed as arising from the fragmentation of c- or b-quarks. The observed yield in each channel is consistent with the Standard Model background expectation. Leptoquarks with masses below 1.8TeV and 1.7TeV are excluded in the electron and muon channels, respectively, assuming a branching ratio into a charged lepton and a quark of 100%, with minimal dependence on the quark avour. Upper limits on the aforementioned branching ratio are also given as a function of the leptoquark mass. ; 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 ; NRC, Canada ; Canada Foundation for Innovation ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; 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 ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; European Union (EU) ; Horizon 2020, European Union ; European Union (EU) ; COST, 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 ; Herakleitos programme - EU-ESF, 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
This paper presents a search for new heavy particles decaying into a pair of top quarks using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of s√ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The search is performed using events consistent with pair production of high-transverse-momentum top quarks and their subsequent decays into the fully hadronic final states. The analysis is optimized for resonances decaying into a tt¯ pair with mass above 1.4 TeV, exploiting a dedicated multivariate technique with jet substructure to identify hadronically decaying top quarks using large-radius jets and evaluating the background expectation from data. No significant deviation from the background prediction is observed. Limits are set on the production cross-section times branching fraction for the new Z′ boson in a topcolor-assisted-technicolor model. The Z′ boson masses below 3.9 and 4.7 TeV are excluded at 95% confidence level for the decay widths of 1% and 3%, respectively. ; 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 ; Canada Foundation for Innovation ; NRC, Canada ; CERN ; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; MINECO, Spain ; SRC, Sweden ; Wallenberg Foundation, Sweden ; SERI, Switzerland ; Swiss National Science Foundation (SNSF) ; Canton of Bern, Switzerland ; Canton of Bern, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; Science & Technology Facilities Council (STFC) ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; BCKDF, Canada ; CANARIE, Canada ; Compute Canada, Canada ; CRC, Canada ; European Union (EU) European Research Council (ERC) ; European Union (EU) ; Horizon 2020, European Union ; COST, 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 ; CERCA Programme Generalitat de Catalunya, Spain ; PROMETEO Programme Generalitat Valenciana, Spain ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; Leverhulme Trust
A search for new physics with non-resonant signals in dielectron and dimuon final states in the mass range above 2 TeV is presented. This is the first search for nonresonant signals in dilepton final states at the LHC to use a background estimate from the data. The data, corresponding to an integrated luminosity of 139 fb−1 , were recorded by the ATLAS experiment in proton-proton collisions at a center-of-mass energy of √ s = 13 TeV during Run 2 of the Large Hadron Collider. The benchmark signal signature is a two-quark and two-lepton contact interaction, which would enhance the dilepton event rate at the TeV mass scale. To model the contribution from background processes a functional form is fit to the dilepton invariant-mass spectra in data in a mass region below the region of interest. It is then extrapolated to a high-mass signal region to obtain the expected background there. No significant deviation from the expected background is observed in the data. Upper limits at 95% CL on the number of events and the visible cross-section times branching fraction for processes involving new physics are provided. Observed (expected) 95% CL lower limits on the contact interaction energy scale reach 35.8 (37.6) TeV. ; 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) ; Canada Foundation for Innovation ; NRC, Canada ; 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) ; 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 ; MNE/IFA, Romania ; MES of Russia, Russia Federation ; NRC KI, Russia Federation ; JINR ; MESTD, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia ; MIZS, Slovenia ; DST/NRF, South Africa ; Spanish Government ; 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 ; European Union (EU) European Research Council (ERC) ; European Union (EU) ; Horizon 2020, European Union ; European Union (EU) ; COST, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; Alexander von Humboldt Foundation ; Herakleitos programme ; Thales programme ; 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
