The associated production of vector bosons V (W, Z or gamma) and jets originating from heavyflavour (c or b) quarks is a large background source in measurements of other standard model processes, Higgs boson studies, and many searches for physics beyond the standard model. The study of events with a vector boson accompanied by heavy-flavour jets is crucial to refine the theoretical calculations in perturbative QCD, as well as to validate associated Monte Carlo predictions. Differential cross sections in V+ c/b jets are measured as a function of several kinematic observables with the CMS detector at 8 and 13 TeV. The study of the associated production of a vector boson with jets from a c-quark is especially interesting, as it allows to extract information on the proton parton density functions. 8
{"title":"The associated production of vector bosons and jets originating from heavy-flavour quarks and constrain on PDFs in CMS","authors":"A. Stepennov","doi":"10.22323/1.390.0505","DOIUrl":"https://doi.org/10.22323/1.390.0505","url":null,"abstract":"The associated production of vector bosons V (W, Z or gamma) and jets originating from heavyflavour (c or b) quarks is a large background source in measurements of other standard model processes, Higgs boson studies, and many searches for physics beyond the standard model. The study of events with a vector boson accompanied by heavy-flavour jets is crucial to refine the theoretical calculations in perturbative QCD, as well as to validate associated Monte Carlo predictions. Differential cross sections in V+ c/b jets are measured as a function of several kinematic observables with the CMS detector at 8 and 13 TeV. The study of the associated production of a vector boson with jets from a c-quark is especially interesting, as it allows to extract information on the proton parton density functions. 8","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77248563","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}
As shown recently, the ground state of quantum chromodynamics (QCD) in sufficiently strong magnetic fields and at moderate baryon densities carries a crystalline condensate of neutral pions: the chiral soliton lattice (CSL). This phase cannot be realized from first principles using standard latticeMonte Carlo simulations due to the infamous sign problem. On the other hand, we show that CSL, or a similar inhomogeneous phase, also appears in the phase diagram of a class of vector-like gauge theories that do not suffer from the sign problem even in the presence of a baryon chemical potential and external magnetic field. Hence, we give a class of explicit counterexamples to the long-standing conjecture that positivity of the determinant of the Dirac operator (that is, absence of the sign problem) in a vector-like gauge theory precludes spontaneous breaking of translational invariance, and thus implies the absence of inhomogeneous phases in the phase diagram of the theory.
{"title":"An Inhomogeneous Phase in Quark Matter without the Sign Problem","authors":"H. Kolešová","doi":"10.22323/1.390.0525","DOIUrl":"https://doi.org/10.22323/1.390.0525","url":null,"abstract":"As shown recently, the ground state of quantum chromodynamics (QCD) in sufficiently strong magnetic fields and at moderate baryon densities carries a crystalline condensate of neutral pions: the chiral soliton lattice (CSL). This phase cannot be realized from first principles using standard latticeMonte Carlo simulations due to the infamous sign problem. On the other hand, we show that CSL, or a similar inhomogeneous phase, also appears in the phase diagram of a class of vector-like gauge theories that do not suffer from the sign problem even in the presence of a baryon chemical potential and external magnetic field. Hence, we give a class of explicit counterexamples to the long-standing conjecture that positivity of the determinant of the Dirac operator (that is, absence of the sign problem) in a vector-like gauge theory precludes spontaneous breaking of translational invariance, and thus implies the absence of inhomogeneous phases in the phase diagram of the theory.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85717370","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}
Diffractive processes are important non-perturbative phenomena of strong interaction, which are studied in various measurements at the LHC. Recent results of the CMS and TOTEM experiments are presented in this paper. First, the measurement of central exclusive and semiexclusive c+c− production at 5.02 and 13 TeV is discussed. The total and differential cross sections of final states with ?T (c) > 0.2 GeV, |[(c) | < 2.4 are measured. In the second part of the paper, the measurement of the total and differential cross sections as functions of four-momentum transfer squared C and proton fractional momentum loss b, in the 0.03 < |C | < 1.0 GeV2 and 0 < b < 0.1 kinematic region, with at least two jets with ?T > 40 GeV and |[ | < 4.4 is presented. This latter measurement utilized the proton tagging capabilities of the Roman Pot detectors of the TOTEM experiment.
{"title":"Central exclusive and diffractive physics measurements at CMS and TOTEM","authors":"O. Surányi, Totem Collaborations","doi":"10.22323/1.390.0508","DOIUrl":"https://doi.org/10.22323/1.390.0508","url":null,"abstract":"Diffractive processes are important non-perturbative phenomena of strong interaction, which are studied in various measurements at the LHC. Recent results of the CMS and TOTEM experiments are presented in this paper. First, the measurement of central exclusive and semiexclusive c+c− production at 5.02 and 13 TeV is discussed. The total and differential cross sections of final states with ?T (c) > 0.2 GeV, |[(c) | < 2.4 are measured. In the second part of the paper, the measurement of the total and differential cross sections as functions of four-momentum transfer squared C and proton fractional momentum loss b, in the 0.03 < |C | < 1.0 GeV2 and 0 < b < 0.1 kinematic region, with at least two jets with ?T > 40 GeV and |[ | < 4.4 is presented. This latter measurement utilized the proton tagging capabilities of the Roman Pot detectors of the TOTEM experiment.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85497729","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 underlying event in a proton-proton collision consists of multiple-parton interactions and beam remnants, which typically involve low energy scales. The modeling of these aspects of a collision is not always calculable in perturbative quantum chromodynamics, and is governed by phenomenological parameters that need to be "tuned" to observed data. The results of such an underlying-event tuning performed by the CMS experiment for the Pythia 8 and Herwig 7 generators are presented. Various assumptions in the proton parton distribution functions and parton shower development are tested. The derived tunes are validated using data of a wide range of physics processes, and provide a good description of CMS data at a center-of-mass energy √ s = 13 TeV.
{"title":"Monte Carlo Modeling and Tuning in CMS","authors":"G. Onsem","doi":"10.22323/1.390.0515","DOIUrl":"https://doi.org/10.22323/1.390.0515","url":null,"abstract":"The underlying event in a proton-proton collision consists of multiple-parton interactions and beam remnants, which typically involve low energy scales. The modeling of these aspects of a collision is not always calculable in perturbative quantum chromodynamics, and is governed by phenomenological parameters that need to be \"tuned\" to observed data. The results of such an underlying-event tuning performed by the CMS experiment for the Pythia 8 and Herwig 7 generators are presented. Various assumptions in the proton parton distribution functions and parton shower development are tested. The derived tunes are validated using data of a wide range of physics processes, and provide a good description of CMS data at a center-of-mass energy √ s = 13 TeV.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85703331","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":"Study of phi(2170) at BESIII","authors":"Linqin Huang","doi":"10.22323/1.390.0463","DOIUrl":"https://doi.org/10.22323/1.390.0463","url":null,"abstract":"","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87407458","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 Mu2e experiment, currently under construction at Fermilab, will search for coherent neutrinoless muon to electron conversion, extending the sensitivity of searches for charged lepton flavour violation by four orders of magnitude in 3-5 years of data-taking. This improved sensitivity is made possible by using a pulsed beam structure that is optimized for reducing prompt backgrounds when muons are stopped on an aluminium target. Producing a high-rate pulsed beam is achieved using resonant extraction of a circulating proton beam, an “AC dipole” with a time-varying field to deflect out-of-time protons, and a system to measure the extinction of out-of-time beam particles incident on the muon production target. These proceedings summarize the systems that have been designed to achieve the required level of extinction and to continuously place limits on the presence of out-of-time beam hitting the production target with a sensitivity of <10.
{"title":"Resonant Extraction and Extinction Measurement for the Mu2e Experiment","authors":"Matthew T. Jones","doi":"10.22323/1.390.0689","DOIUrl":"https://doi.org/10.22323/1.390.0689","url":null,"abstract":"The Mu2e experiment, currently under construction at Fermilab, will search for coherent neutrinoless muon to electron conversion, extending the sensitivity of searches for charged lepton flavour violation by four orders of magnitude in 3-5 years of data-taking. This improved sensitivity is made possible by using a pulsed beam structure that is optimized for reducing prompt backgrounds when muons are stopped on an aluminium target. Producing a high-rate pulsed beam is achieved using resonant extraction of a circulating proton beam, an “AC dipole” with a time-varying field to deflect out-of-time protons, and a system to measure the extinction of out-of-time beam particles incident on the muon production target. These proceedings summarize the systems that have been designed to achieve the required level of extinction and to continuously place limits on the presence of out-of-time beam hitting the production target with a sensitivity of <10.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87074612","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 measurements of quarkonia and doubly-heavy hadrons in pp collisions provide crucial inputs to study both perturbative and non-perturbative quantum chromodynamics. LHCb has a broad physics program of studies of quarkonia and doubly-heavy hadrons. In this proceeding, six recent measurements from the LHCb collaboration are reported: the ψ(2S) production cross-sections measurement, the updated measurement of ηc(1S) production cross-section, the observation of a new charmonium state X(3842), the observation of an excited B c state, the precision measurement of B c mass, and end this report with the first search of Ξbc .
{"title":"Studies of quarkonia and doubly-heavy hadrons at LHCb","authors":"Zhiyu Xiang","doi":"10.22323/1.390.0522","DOIUrl":"https://doi.org/10.22323/1.390.0522","url":null,"abstract":"The measurements of quarkonia and doubly-heavy hadrons in pp collisions provide crucial inputs to study both perturbative and non-perturbative quantum chromodynamics. LHCb has a broad physics program of studies of quarkonia and doubly-heavy hadrons. In this proceeding, six recent measurements from the LHCb collaboration are reported: the ψ(2S) production cross-sections measurement, the updated measurement of ηc(1S) production cross-section, the observation of a new charmonium state X(3842), the observation of an excited B c state, the precision measurement of B c mass, and end this report with the first search of Ξbc .","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77071769","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 ATLAS upgrade for HL-LHC operation includes the installation of an entirely new all-silicon Inner Tracker (ITk). The silicon strip region comprises 165 m of instrumented area, made possible by mass production of silicon strip sensors. This area is covered in a nearly hermetic way. Multiple sensor shapes are utilized: square sensors in the barrel part, and skewed trapezoidal sensors with curved edges to provide a continuous coverage of the disc surface in the endcap part of a detector. As a result, there are 8 different strip sensor types in the system. They all feature AC-coupled n-in-p strips with polysilicon biasing, developed to withstand the total fluence of 1.6 · 10 neq/cm 2 and the total ionizing dose of 66 Mrad. Following many years of R&D and 4 prototype submissions and evaluations, the project transitioned into pre-production, where 5 % of the total volume is produced in all 8 designs. In this contribution we will summarize the results obtained for the latest prototype sensors ATLAS17LS, a long-strip type sensor for the barrel part, the properties of which are expected to be comparable with the pre-production sensors.
{"title":"Radiation-Hard Silicon Strip Sensors for the ATLAS Phase-2 Upgrade","authors":"V. Latonova","doi":"10.22323/1.390.0892","DOIUrl":"https://doi.org/10.22323/1.390.0892","url":null,"abstract":"The ATLAS upgrade for HL-LHC operation includes the installation of an entirely new all-silicon Inner Tracker (ITk). The silicon strip region comprises 165 m of instrumented area, made possible by mass production of silicon strip sensors. This area is covered in a nearly hermetic way. Multiple sensor shapes are utilized: square sensors in the barrel part, and skewed trapezoidal sensors with curved edges to provide a continuous coverage of the disc surface in the endcap part of a detector. As a result, there are 8 different strip sensor types in the system. They all feature AC-coupled n-in-p strips with polysilicon biasing, developed to withstand the total fluence of 1.6 · 10 neq/cm 2 and the total ionizing dose of 66 Mrad. Following many years of R&D and 4 prototype submissions and evaluations, the project transitioned into pre-production, where 5 % of the total volume is produced in all 8 designs. In this contribution we will summarize the results obtained for the latest prototype sensors ATLAS17LS, a long-strip type sensor for the barrel part, the properties of which are expected to be comparable with the pre-production sensors.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73660978","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 CMS detector features the world’s largest silicon tracker, comprising a strip and a pixel detector. However, the CMS tracker is expected to reach the end of its lifetime after Run 3 of the LHC, and a new device will be installed during Long Shutdown 3. The aim is to at least maintain, and if possible to improve, the performance of the present device, under much harsher conditions in terms of radiation levels, hit rates and pileup. The new tracker will feature an Inner Tracker with silicon pixel modules and an Outer Tracker with strip and macro-pixel silicon modules. The Inner Tracker will extend the acceptance up to much higher pseudorapidities. More than 4000 hybrid pixel modules with a reduced cell size and with a readout chip based on the RD53 development will be installed. For the Outer Tracker an innovative detector concept was developed, allowing the contribution of tracker data to the first trigger level. For this the data volume that must be sent out at 40 MHz for the trigger decision is reduced already on-module, as each module carries two silicon sensors on top of each other with a distance of a few millimetres, read out by the same front-end ASICs. In that way a rough estimate of the transverse momentum of each particle can be made by exploiting the strong CMS magnetic field of 3.8 T. The module and detector designs are built around this idea. The detector concept and the expected performance will be presented, and important design choices along with the present status will be discussed.
{"title":"The CMS tracker upgrade for the High Luminosity LHC","authors":"K. Klein","doi":"10.22323/1.390.0852","DOIUrl":"https://doi.org/10.22323/1.390.0852","url":null,"abstract":"The CMS detector features the world’s largest silicon tracker, comprising a strip and a pixel detector. However, the CMS tracker is expected to reach the end of its lifetime after Run 3 of the LHC, and a new device will be installed during Long Shutdown 3. The aim is to at least maintain, and if possible to improve, the performance of the present device, under much harsher conditions in terms of radiation levels, hit rates and pileup. The new tracker will feature an Inner Tracker with silicon pixel modules and an Outer Tracker with strip and macro-pixel silicon modules. The Inner Tracker will extend the acceptance up to much higher pseudorapidities. More than 4000 hybrid pixel modules with a reduced cell size and with a readout chip based on the RD53 development will be installed. For the Outer Tracker an innovative detector concept was developed, allowing the contribution of tracker data to the first trigger level. For this the data volume that must be sent out at 40 MHz for the trigger decision is reduced already on-module, as each module carries two silicon sensors on top of each other with a distance of a few millimetres, read out by the same front-end ASICs. In that way a rough estimate of the transverse momentum of each particle can be made by exploiting the strong CMS magnetic field of 3.8 T. The module and detector designs are built around this idea. The detector concept and the expected performance will be presented, and important design choices along with the present status will be discussed.","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89772336","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":"Performance of the CMS Level-1 Trigger during Run 2","authors":"H. Kwon","doi":"10.22323/1.390.0806","DOIUrl":"https://doi.org/10.22323/1.390.0806","url":null,"abstract":"","PeriodicalId":20428,"journal":{"name":"Proceedings of 40th International Conference on High Energy physics — PoS(ICHEP2020)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90160932","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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