In this proceeding we review the status of theoretical predictions for top pair production and decay at differential level. Concerning stable tops we focus on the NNLO QCD+NLO EW combination, the NNLO+NNLL$'$ calculation and the merged $t bar t+t bar t j$ results at NLO QCD+EW accuracy. We further present results at the decay level including off-shell effects in the semi-leptonic decay mode of the top-quark pair at NLO in QCD.
本文综述了差分水平上顶对产生和衰减的理论预测现状。对于稳定顶，我们重点研究了NNLO QCD+ NNLO EW组合，NNLO+NNLL$'$计算和合并的$t bar t+t bar t j$结果在NLO QCD+EW精度。我们进一步介绍了在QCD中NLO的顶夸克对的半轻子衰变模式中的脱壳效应。
{"title":"Status of theoretical predictions for top pair production cross section","authors":"I. Tsinikos","doi":"10.22323/1.321.0238","DOIUrl":"https://doi.org/10.22323/1.321.0238","url":null,"abstract":"In this proceeding we review the status of theoretical predictions for top pair production and decay at differential level. Concerning stable tops we focus on the NNLO QCD+NLO EW combination, the NNLO+NNLL$'$ calculation and the merged $t bar t+t bar t j$ results at NLO QCD+EW accuracy. We further present results at the decay level including off-shell effects in the semi-leptonic decay mode of the top-quark pair at NLO in QCD.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131078642","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}
A precise measurement of the LHC luminosity is a key component of the ATLAS program: its uncertainty is a systematic error in all cross-section measurements, from the Standard Model processes to new discoveries, and for some precise measurements it can be the dominant error. To be predictive a precision compatible with PDF uncertainty ( 1-2%) is desired. LUCID (LUminosity Cherenkov Integrating Detector) is a luminometer sensitive to charged particles produced at the interaction point. It is the only ATLAS detector totally dedicated to this purpose and the main one during LHC RUN 2. After the RUN 1 shutdown, LUCID had to be redesigned in order to cope with the data taking conditions foreseen for RUN 2. The new detector, calibration system and electronics will be described, together with a preliminary result of the systematic uncertainty on the 2017 luminosity measurement.
对大型强子对撞机亮度的精确测量是ATLAS项目的关键组成部分:它的不确定性是所有横截面测量的系统误差，从标准模型过程到新发现，对于某些精确测量，它可能是主要误差。为了进行预测，需要与PDF不确定度(1-2%)兼容的精度。LUCID (LUminosity Cherenkov积分检测器)是一种对相互作用点产生的带电粒子敏感的光度计。它是唯一一个完全专用于此目的的ATLAS探测器，也是LHC RUN 2期间的主要探测器。在RUN 1关闭后，LUCID必须重新设计，以应对RUN 2预期的数据获取条件。将介绍新的探测器、校准系统和电子设备，以及2017年光度测量系统不确定度的初步结果。
{"title":"LUCID: The ATLAS Luminosity Detector","authors":"L. Fabbri","doi":"10.22323/1.321.0032","DOIUrl":"https://doi.org/10.22323/1.321.0032","url":null,"abstract":"A precise measurement of the LHC luminosity is a key component of the ATLAS program: its uncertainty is a systematic error in all cross-section measurements, from the Standard Model processes to new discoveries, and for some precise measurements it can be the dominant error. \u0000To be predictive a precision compatible with PDF uncertainty ( 1-2%) is desired. \u0000LUCID (LUminosity Cherenkov Integrating Detector) is a luminometer sensitive to charged particles produced at the interaction point. It is the only ATLAS detector totally dedicated to this purpose and the main one during LHC RUN 2. After the RUN 1 shutdown, LUCID had to be redesigned in order to cope with the data taking conditions foreseen for RUN 2. The new detector, calibration system and electronics will be described, together with a preliminary result of the systematic uncertainty on the 2017 luminosity measurement.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127363879","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 LHCb detector is a single-arm forward spectrometer, which measures proton-proton interactions at the LHC. For Run II (2015-2018) LHCb has introduced a novel real-time detector alignment and calibration strategy. Data collected at the start of the fill are processed and used to update the alignment, while the calibration constants are evaluated for each run. In this document an overview of the real-time alignment and calibration strategy is presented, followed by the discussion of the latest developments.
大型强子对撞机探测器是一台单臂前向光谱仪，用于测量大型强子对撞机中的质子-质子相互作用。对于Run II (2015-2018)， LHCb引入了一种新的实时探测器对准和校准策略。在填充开始时收集的数据被处理并用于更新对齐，同时每次运行评估校准常数。本文概述了实时对准和校准策略，然后讨论了最新的发展。
{"title":"LHCb full-detector real-time alignment and calibration: latest developments and perspectives","authors":"A. Dziurda, A. Mogini","doi":"10.22323/1.321.0047","DOIUrl":"https://doi.org/10.22323/1.321.0047","url":null,"abstract":"The LHCb detector is a single-arm forward spectrometer, which measures proton-proton interactions at the LHC. For Run II (2015-2018) LHCb has introduced a novel real-time detector alignment and calibration strategy. Data collected at the start of the fill are processed and used to update the alignment, while the calibration constants are evaluated for each run. In this document an overview of the real-time alignment and calibration strategy is presented, followed by the discussion of the latest developments.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124469643","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 purpose of the ATLAS Forward Proton (AFP) detector is to measure protons scattered at very small angles. AFP aims to study diffractive events, exclusive production and photon induced interactions. The first arm of AFP with 3D pixel detectors was installed in early 2016 and data to study the tracker performance were recorded later that year during special low luminosity runs. The full two-arm setup (on both sides of the interaction point) was installed during the 2016/2017 LHC winter shutdown. In 2017, AFP participated in the ATLAS high-luminosity data taking on a daily basis. In addition, several special runs with reduced luminosity were taken. This paper presents the AFP detector and its performance during 2016 and 2017.
{"title":"ATLAS Forward Proton Detector","authors":"Chiara Grieco","doi":"10.22323/1.321.0031","DOIUrl":"https://doi.org/10.22323/1.321.0031","url":null,"abstract":"The purpose of the ATLAS Forward Proton (AFP) detector is to measure protons scattered at very small angles. AFP aims to study diffractive events, exclusive production and photon induced interactions. The first arm of AFP with 3D pixel detectors was installed in early 2016 and data to study the tracker performance were recorded later that year during special low luminosity runs. The full two-arm setup (on both sides of the interaction point) was installed during the 2016/2017 LHC winter shutdown. In 2017, AFP participated in the ATLAS high-luminosity data taking on a daily basis. In addition, several special runs with reduced luminosity were taken. This paper presents the AFP detector and its performance during 2016 and 2017.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122967930","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 production and decay properties of the top-quark are sensitive to new physics in several scenarios beyond the Standard Model. LHCb is the only experiment where the top-quark can be studied in the forward region exploiting, therefore, production mechanisms different from ATLAS and CMS experiments. The first cross section measurement in the forward region has been performed at $sqrt{s}=7, 8$ TeV. The most precise determination at LHCb uses data collected at $sqrt{s}=13$ TeV requiring final states with a $b$-jet and two leptons, muon and electron, coming from the $W$ decay. A description of these measurements is provided together with comparison with theories.
{"title":"Top pair production cross sections at LHCb","authors":"D. Lucchesi","doi":"10.22323/1.321.0241","DOIUrl":"https://doi.org/10.22323/1.321.0241","url":null,"abstract":"The production and decay properties of the top-quark are sensitive to new physics in several scenarios beyond the Standard Model. LHCb is the only experiment where the top-quark can be studied in the forward region exploiting, therefore, production mechanisms different from ATLAS and CMS experiments. The first cross section measurement in the forward region has been performed at $sqrt{s}=7, 8$ TeV. The most precise determination at LHCb uses data collected at $sqrt{s}=13$ TeV requiring final states with a $b$-jet and two leptons, muon and electron, coming from the $W$ decay. A description of these measurements is provided together with comparison with theories.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116993014","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}
In 2017 the Large Hadron Collider at CERN has provided an astonishing 50 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV. The CMS detector has been able to record about 90% of this data. During this period, the CMS electromagnetic calorimeter (ECAL), based on 75848 scintillating PbWO4 crystals and a silicon and lead preshower, has continued exhibiting excellent performance with a very stable data acquisition system. The ECAL DAQ system follows a modular and scalar schema: the crystals are divided in sectors, each of them controlled by 3 interconnected boards. These boards are responsible for the configuration and control of the front-end electronics, the generation of trigger primitives for the central CMS first level trigger, and the collection of data. A multi-machine distributed software configures the electronic boards and follows the life cycle of the acquisition process. The ECAL electronics modular configuration is reflected in the software where a tree control structure is applied. Through a master web application, the user controls the communication with the sub-applications that are responsible for the off-detector board configurations. Since the beginning of Run 2 in 2015, many improvements to the ECAL DAQ have been implemented to reduce occasional errors, as well as to mitigate single event upsets in the front-end electronics, and to improve the efficiency. Efforts at the software level have been made to introduce automatic recovery in case of errors. These procedures are mandatory to have a reliable and efficient acquisition system.
{"title":"The CMS ECAL data acquisition system and its performance at LHC Run 2","authors":"D. Mapelli","doi":"10.22323/1.321.0069","DOIUrl":"https://doi.org/10.22323/1.321.0069","url":null,"abstract":"In 2017 the Large Hadron Collider at CERN has provided an astonishing 50 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV. The CMS detector has been able to record about 90% of this data. During this period, the CMS electromagnetic calorimeter (ECAL), based on 75848 scintillating PbWO4 crystals and a silicon and lead preshower, has continued exhibiting excellent performance with a very stable data acquisition system. The ECAL DAQ system follows a modular and scalar schema: the crystals are divided in sectors, each of them controlled by 3 interconnected boards. These boards are responsible for the configuration and control of the front-end electronics, the generation of trigger primitives for the central CMS first level trigger, and the collection of data. A multi-machine distributed software configures the electronic boards and follows the life cycle of the acquisition process. The ECAL electronics modular configuration is reflected in the software where a tree control structure is applied. Through a master web application, the user controls the communication with the sub-applications that are responsible for the off-detector board configurations. Since the beginning of Run 2 in 2015, many improvements to the ECAL DAQ have been implemented to reduce occasional errors, as well as to mitigate single event upsets in the front-end electronics, and to improve the efficiency. Efforts at the software level have been made to introduce automatic recovery in case of errors. These procedures are mandatory to have a reliable and efficient acquisition system.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123187102","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}
This note reports on current education and outreach activities coordinated and supported by the LHC collaborations. These include a growing variety of efforts designed to inform the public, educate students, and communicate our progress to policy makers around the world. It also emphasises the importance of these efforts, given the recent rise of anti-science sentiment in influential political arenas, as well as the effect of social media as a growing platform for disinformation. The note further describes support provided by CERN and by the International Particle Physics Outreach Group (IPPOG) to create high-quality, coherent content backing these efforts, as well as a platform for the effective development and sharing of projects and ideas. Finally, the note underlines progress being made by the experiments to recognise and support outreach as an important responsibility for all collaboration members, and by some institutes to encourage outreach as a requirement of scientific research. It concludes by pointing out certain areas where more work is needed.
{"title":"Particle Physics Outreach: What we are doing and what we could be doing","authors":"S. Goldfarb","doi":"10.22323/1.321.0103","DOIUrl":"https://doi.org/10.22323/1.321.0103","url":null,"abstract":"This note reports on current education and outreach activities coordinated and supported by the LHC collaborations. These include a growing variety of efforts designed to inform the public, educate students, and communicate our progress to policy makers around the world. It also emphasises the importance of these efforts, given the recent rise of anti-science sentiment in influential political arenas, as well as the effect of social media as a growing platform for disinformation. The note further describes support provided by CERN and by the International Particle Physics Outreach Group (IPPOG) to create high-quality, coherent content backing these efforts, as well as a platform for the effective development and sharing of projects and ideas. Finally, the note underlines progress being made by the experiments to recognise and support outreach as an important responsibility for all collaboration members, and by some institutes to encourage outreach as a requirement of scientific research. It concludes by pointing out certain areas where more work is needed.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128848661","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}
Several new physics models that extend the Standard Model require the existence of Long-Lived Particle (LLP) as a solution for the problems like Dark Matter and Naturalness. The ATLAS Phase-II upgrade detector and the expected large data set from high luminosity LHC upgrade offers an opportunity to probe the yet unexplored region of the phase space. For muon spectrometer based searches, neutral LLP decaying to collimated jets of leptons and light hadrons (lepton-jets) are of great interest. These particles offer an unique signature that can lead to an early discovery. New triggering techniques and algorithm have been developed and studied to improve the selection of highly boosted lepton-jets.
{"title":"Long-Lived Particles at HL-LHC with the ATLAS detector","authors":"Cristiano Sebastiani","doi":"10.22323/1.321.0080","DOIUrl":"https://doi.org/10.22323/1.321.0080","url":null,"abstract":"Several new physics models that extend the Standard Model require the existence of Long-Lived Particle (LLP) as a solution for the problems like Dark Matter and Naturalness. The ATLAS Phase-II upgrade detector and the expected large data set from high luminosity LHC upgrade offers an opportunity to probe the yet unexplored region of the phase space. For muon spectrometer based searches, neutral LLP decaying to collimated jets of leptons and light hadrons (lepton-jets) are of great interest. These particles offer an unique signature that can lead to an early discovery. New triggering techniques and algorithm have been developed and studied to improve the selection of highly boosted lepton-jets.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116751230","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 measurement of Higgs properties poses significant constraints on physics beyond the Standard Model. These are compared with direct searches of additional scalar states of an extended Higgs sector. As a simple example, we consider a scalar singlet coupled to the other particles only through its mixing with the Higgs boson, which appears in several motivated extensions of the Standard Model. The prospects for the discovery of a generic singlet at the various stages of the LHC, as well as at future high-energy colliders, are studied, and the reach of direct searches is compared with the precision attainable with Higgs couplings measurements. The results are then applied to the NMSSM and Twin Higgs.
{"title":"Higgs measurements and searches as a portal to physics beyond the Standard Model","authors":"D. Buttazzo","doi":"10.22323/1.321.0155","DOIUrl":"https://doi.org/10.22323/1.321.0155","url":null,"abstract":"The measurement of Higgs properties poses significant constraints on physics beyond the Standard Model. These are compared with direct searches of additional scalar states of an extended Higgs sector. As a simple example, we consider a scalar singlet coupled to the other particles only through its mixing with the Higgs boson, which appears in several motivated extensions of the Standard Model. The prospects for the discovery of a generic singlet at the various stages of the LHC, as well as at future high-energy colliders, are studied, and the reach of direct searches is compared with the precision attainable with Higgs couplings measurements. The results are then applied to the NMSSM and Twin Higgs.","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"91 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131219726","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 review the current status of B-mixing observables and point out the crucial importance of a control of the hadronic uncertainties for ruling out or confirming hints of BSM physics. In addition we introduce a rating system for theory predictions for lifetimes and mixing observables, that classifies the quality of the corresponding SM values ranging from no star to ****
{"title":"Theory of mixing and CP violation","authors":"A. Lenz","doi":"10.22323/1.321.0174","DOIUrl":"https://doi.org/10.22323/1.321.0174","url":null,"abstract":"We review the current status of B-mixing observables and point out the crucial importance of a control of the hadronic uncertainties for ruling out or confirming hints of BSM physics. In addition we introduce a rating system for theory predictions for lifetimes and mixing observables, that classifies the quality of the corresponding SM values ranging from no star to ****","PeriodicalId":346295,"journal":{"name":"Proceedings of Sixth Annual Conference on Large Hadron Collider Physics — PoS(LHCP2018)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132916482","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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