The sPHENIX experiment is the successor to the PHENIX experiment at RHIC and is optimized to study heavy flavor and jets arising from heavy ion collisions. The detector utilizes advanced technologies such as a monolithic active pixel vertex detector while also repurposing technologies originally from other high energy experiments such as BaBar, ATLAS and ALICE. The design and status of the sPHENIX detector is detailed along with the projected physics capabilities and planned measurements that the collaboration will work to achieve. sPHENIX is expected to begin data taking in 2023.
{"title":"The sPHENIX experiment at RHIC","authors":"C. Dean","doi":"10.22323/1.390.0731","DOIUrl":"https://doi.org/10.22323/1.390.0731","url":null,"abstract":"The sPHENIX experiment is the successor to the PHENIX experiment at RHIC and is optimized to study heavy flavor and jets arising from heavy ion collisions. The detector utilizes advanced technologies such as a monolithic active pixel vertex detector while also repurposing technologies originally from other high energy experiments such as BaBar, ATLAS and ALICE. The design and status of the sPHENIX detector is detailed along with the projected physics capabilities and planned measurements that the collaboration will work to achieve. sPHENIX is expected to begin data taking in 2023.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75021870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The precise measurement of the luminosity is one of the key requirements for every ATLAS analysis at the Large Hadron Collider (LHC) at CERN. Particularly in high precision measurements, the uncertainty on the luminosity can be one of the main limitations. Therefore, its reduction is the prime goal of the ATLAS luminosity programme, requiring a precise understanding of the con-tributing factors. The two largest individual components are the calibration transfer (extrapolating the measurement from the calibration regime to the physics regime) and the long term stability (stability of the measurement typically over a whole year), both determinations involving the track counting luminosity measurement. This technique uses charged particle tracks to measure the delivered luminosity. The uncertainty of this measurement is dependent on the track selection and therefore, the performance of three selections is compared over different LHC fill configurations. The goal of this study is to determine the stability of the measurement and if possible correct observed effects.
{"title":"Measuring luminosity with track counting in the ATLAS experiment","authors":"P. Moder","doi":"10.22323/1.390.0811","DOIUrl":"https://doi.org/10.22323/1.390.0811","url":null,"abstract":"The precise measurement of the luminosity is one of the key requirements for every ATLAS analysis at the Large Hadron Collider (LHC) at CERN. Particularly in high precision measurements, the uncertainty on the luminosity can be one of the main limitations. Therefore, its reduction is the prime goal of the ATLAS luminosity programme, requiring a precise understanding of the con-tributing factors. The two largest individual components are the calibration transfer (extrapolating the measurement from the calibration regime to the physics regime) and the long term stability (stability of the measurement typically over a whole year), both determinations involving the track counting luminosity measurement. This technique uses charged particle tracks to measure the delivered luminosity. The uncertainty of this measurement is dependent on the track selection and therefore, the performance of three selections is compared over different LHC fill configurations. The goal of this study is to determine the stability of the measurement and if possible correct observed effects.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82365476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quarkonia photo-production and Z production in heavy ion collisions at LHCb","authors":"G. Manca","doi":"10.22323/1.390.0552","DOIUrl":"https://doi.org/10.22323/1.390.0552","url":null,"abstract":"","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81829874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jets are an important tool to study the hot, dense matter produced in Pb+Pb collisions at the LHC. They are produced at the early stages of the collisions and are expected to be modified as they propagate through the hot and dense medium. This leads to energy loss as well as modification of the jet structure. These proceedings highlight some of the latest jet measurements from ATLAS measured in 260 pb−1 and 1.7 nb−1 of pp and Pb+Pb collision data, respectively, at 5.02 TeV per nucleon pair. The results shown include measurements of the dijet asymmetry as a function of the leading jet transverse momentum, the suppression pattern of the internal structure, revealed when reconstructing jets with the anti-kt algorithm using large radius parameters, and measurements of particles recoiling against the Z boson. The data provide important information to understand the strength and mechanism of jet quenching.
{"title":"Jet Production in Heavy Ion Collisions with the ATLAS Experiment","authors":"H. Santos","doi":"10.22323/1.390.0564","DOIUrl":"https://doi.org/10.22323/1.390.0564","url":null,"abstract":"Jets are an important tool to study the hot, dense matter produced in Pb+Pb collisions at the LHC. They are produced at the early stages of the collisions and are expected to be modified as they propagate through the hot and dense medium. This leads to energy loss as well as modification of the jet structure. These proceedings highlight some of the latest jet measurements from ATLAS measured in 260 pb−1 and 1.7 nb−1 of pp and Pb+Pb collision data, respectively, at 5.02 TeV per nucleon pair. The results shown include measurements of the dijet asymmetry as a function of the leading jet transverse momentum, the suppression pattern of the internal structure, revealed when reconstructing jets with the anti-kt algorithm using large radius parameters, and measurements of particles recoiling against the Z boson. The data provide important information to understand the strength and mechanism of jet quenching.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78265795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electroweak bosons produced in lead–lead (Pb+Pb) collisions are an excellent tool to constrain initial-state effects which affect the rates of hard-scattering processes in nucleus–nucleus interactions. The production yields of massive electroweak bosons, observed via their leptonic decay channels, offer a high-precision test of the binary collision scaling expected in Pb+Pb and a way to quantify nuclear modifications of the parton distribution functions (PDFs). The large samples of Pb+Pb data at sNN = 5.02 TeV collected by the ATLAS experiment in 2015, and the corresponding high-statistics pp data at the same collision energy used as a baseline, allow for a detailed experimental study of these phenomena and comparisons to predictions from a variety of theoretical calculations. This report presents the latest ATLAS results on electroweak boson production, including updated results on Z production and high-precisionW boson results in Pb+Pb collisions. Inclusive production of prompt photons in proton–lead (p+Pb) collisions at sNN = 8.16 TeV is also covered. Various predictions of nuclear modifications to PDFs are discussed.
{"title":"Electroweak probes in heavy-ion collisions with ATLAS","authors":"J. Kremer","doi":"10.22323/1.390.0548","DOIUrl":"https://doi.org/10.22323/1.390.0548","url":null,"abstract":"Electroweak bosons produced in lead–lead (Pb+Pb) collisions are an excellent tool to constrain initial-state effects which affect the rates of hard-scattering processes in nucleus–nucleus interactions. The production yields of massive electroweak bosons, observed via their leptonic decay channels, offer a high-precision test of the binary collision scaling expected in Pb+Pb and a way to quantify nuclear modifications of the parton distribution functions (PDFs). The large samples of Pb+Pb data at sNN = 5.02 TeV collected by the ATLAS experiment in 2015, and the corresponding high-statistics pp data at the same collision energy used as a baseline, allow for a detailed experimental study of these phenomena and comparisons to predictions from a variety of theoretical calculations. This report presents the latest ATLAS results on electroweak boson production, including updated results on Z production and high-precisionW boson results in Pb+Pb collisions. Inclusive production of prompt photons in proton–lead (p+Pb) collisions at sNN = 8.16 TeV is also covered. Various predictions of nuclear modifications to PDFs are discussed.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85476741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Future linear e+e- colliders aim for extremely high precision measurements. To achieve this, not only excellent detectors and well controlled machine conditions are needed, but also the best possible estimate of backgrounds. To avoid that lacking channels and too low statistics becomes a major source of systematic errors in data-MC comparisons, all SM channels with the potential to yield at least a few events under the full lifetime of the projects need to be generated, with statistics largely exceeding that of the real data. Also machine conditions need to be accurately taken into account. This includes beam-polarisation, interactions due to the photons inevitably present in the highly focused beams, and coherent interactions of whole bunches. This endeavour has already been partly achieved in preparing design documents for both the ILC and CLIC: Comprehensive samples of fully simulated and reconstructed events are available for use. In this contribution, we present how the generation of physics events at linear colliders is categorised and organised, and the tools used. Also covered is how different aspects of machine conditions, different sources of spurious interactions (such as beam-induced backgrounds) are treated and the tools involved for these aspects.
{"title":"Generating the full SM at linear colliders","authors":"M. Berggren","doi":"10.22323/1.390.0903","DOIUrl":"https://doi.org/10.22323/1.390.0903","url":null,"abstract":"Future linear e+e- colliders aim for extremely high precision measurements. To achieve this, not only excellent detectors and well controlled machine conditions are needed, but also the best possible estimate of backgrounds. To avoid that lacking channels and too low statistics becomes a major source of systematic errors in data-MC comparisons, all SM channels with the potential to yield at least a few events under the full lifetime of the projects need to be generated, with statistics largely exceeding that of the real data. Also machine conditions need to be accurately taken into account. This includes beam-polarisation, interactions due to the photons inevitably present in the highly focused beams, and coherent interactions of whole bunches. This endeavour has already been partly achieved in preparing design documents for both the ILC and CLIC: Comprehensive samples of fully simulated and reconstructed events are available for use. In this contribution, we present how the generation of physics events at linear colliders is categorised and organised, and the tools used. Also covered is how different aspects of machine conditions, different sources of spurious interactions (such as beam-induced backgrounds) are treated and the tools involved for these aspects.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"129 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90422073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite composing 85% of the matter in the universe, the exact nature of dark matter is still unknown. The possibility ofwave-like darkmatter and axions is driving a surge of new experiments that are vitalized by progress in quantum amplification and optics, microwave electronics, high magnetic fields, and cryogenics. We discuss the technology that enables such searches, and break down the experiments by their reliance on different axion couplings. We explain how the Axion Dark Matter eXperiment (ADMX) has achieved sensitivity to a particularly compelling class of dark matter candidates, known as DFSZ axions, in a narrow range of axion masses. Finally, with a new fleet of experiments arriving online, we present their goals to probe as yet unexplored parts of axion parameter space in the coming years.
{"title":"Wave-like Dark Matter and Axions","authors":"C. Bartram","doi":"10.22323/1.390.0004","DOIUrl":"https://doi.org/10.22323/1.390.0004","url":null,"abstract":"Despite composing 85% of the matter in the universe, the exact nature of dark matter is still unknown. The possibility ofwave-like darkmatter and axions is driving a surge of new experiments that are vitalized by progress in quantum amplification and optics, microwave electronics, high magnetic fields, and cryogenics. We discuss the technology that enables such searches, and break down the experiments by their reliance on different axion couplings. We explain how the Axion Dark Matter eXperiment (ADMX) has achieved sensitivity to a particularly compelling class of dark matter candidates, known as DFSZ axions, in a narrow range of axion masses. Finally, with a new fleet of experiments arriving online, we present their goals to probe as yet unexplored parts of axion parameter space in the coming years.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82166178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coupling of the electroweak gauge bosons of the Standard Model (SM) to leptons is flavour universal. Extensions of the SM do not necessarily have this property. Rare decays of heavy flavour are suppressed in the SM and new particles may give sizeable contributions to these processes, therefore, their precise study allows for sensitive tests of lepton flavour universality. Of particular interest are rare b→ sl+l− decays that are well accessible at the LHCb experiment. Recent results from LHCb on lepton flavour universality in rare b→ sl+l− decays are discussed.
{"title":"Lepton Flavour Universality tests in electroweak penguin decays at LHCb","authors":"C. Benito","doi":"10.22323/1.390.0400","DOIUrl":"https://doi.org/10.22323/1.390.0400","url":null,"abstract":"The coupling of the electroweak gauge bosons of the Standard Model (SM) to leptons is flavour universal. Extensions of the SM do not necessarily have this property. Rare decays of heavy flavour are suppressed in the SM and new particles may give sizeable contributions to these processes, therefore, their precise study allows for sensitive tests of lepton flavour universality. Of particular interest are rare b→ sl+l− decays that are well accessible at the LHCb experiment. Recent results from LHCb on lepton flavour universality in rare b→ sl+l− decays are discussed.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82403013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present the search for heavy triboson production, specifically targeting the production of WWW , WW Z , W Z Z and Z Z Z processes in multileptonic final states with 137 fb−1 of data collected by the CMS detector during Run 2 of the LHC at √ s = 13TeV. An event selection consisting of identically charged dileptons and trileptons is constructed to primarily study the WWW process, while the WW Z , W Z Z and Z Z Z processes are explored in four, five and six lepton final states. The analysis utilizes both traditional cut-based and multivariate techniques using boosted decision trees.
{"title":"First observation of production of three massive gauge bosons","authors":"P. Chang","doi":"10.22323/1.390.0325","DOIUrl":"https://doi.org/10.22323/1.390.0325","url":null,"abstract":"We present the search for heavy triboson production, specifically targeting the production of WWW , WW Z , W Z Z and Z Z Z processes in multileptonic final states with 137 fb−1 of data collected by the CMS detector during Run 2 of the LHC at √ s = 13TeV. An event selection consisting of identically charged dileptons and trileptons is constructed to primarily study the WWW process, while the WW Z , W Z Z and Z Z Z processes are explored in four, five and six lepton final states. The analysis utilizes both traditional cut-based and multivariate techniques using boosted decision trees.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89865270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cornelius Grunwald, Stefan Bißmann, J. Erdmann, G. Hiller, K. Kröninger
Over the last years, various efforts were made for interpreting measurements of top-quark observables in the context of the Standard Model Effective Field Theory (SMEFT). We point out two aspects for enhancing fits constraining Wilson coefficients of dimension-six operators that should be considered when aiming towards a global fit of SMEFT coefficients in the top-quark sector. On the one hand, we discuss the advantages of combining measurements from top-quark and physics for constraining top-quark couplings. Considering f(CC̄W) together with BR(̄ → -BW) as an example, we present the steps necessary for including observables from different energy scales in a combined fit and highlight the benefits of this approach. On the other hand, we discuss the importance of taking into account correlations between the uncertainties of measurements by demonstrating the impact correlations can have on the constraints of Wilson coefficients.
{"title":"Enhancing fits of SMEFT Wilson coefficients in the top-quark sector","authors":"Cornelius Grunwald, Stefan Bißmann, J. Erdmann, G. Hiller, K. Kröninger","doi":"10.22323/1.390.0323","DOIUrl":"https://doi.org/10.22323/1.390.0323","url":null,"abstract":"Over the last years, various efforts were made for interpreting measurements of top-quark observables in the context of the Standard Model Effective Field Theory (SMEFT). We point out two aspects for enhancing fits constraining Wilson coefficients of dimension-six operators that should be considered when aiming towards a global fit of SMEFT coefficients in the top-quark sector. On the one hand, we discuss the advantages of combining measurements from top-quark and physics for constraining top-quark couplings. Considering f(CC̄W) together with BR(\u0017̄ → -BW) as an example, we present the steps necessary for including observables from different energy scales in a combined fit and highlight the benefits of this approach. On the other hand, we discuss the importance of taking into account correlations between the uncertainties of measurements by demonstrating the impact correlations can have on the constraints of Wilson coefficients.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77817031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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