Üksiku t-kvargi omaduste mõõtmine CMS-detektoris

Pärast hiljutist Higgsi bosoni avastamist on leitud kõik osakestefüüsika standardmudeli (SM) poolt ennustatud osakesed. Ometi on põhjust arvata, et tegu pole lõpliku teooriaga, kuna mitmed nähtused, nagu tumeaine või neutriinode massid ei ole SM-ga seletatavad. Üks huvitav uurimisobjekt, mille täpsete mõõtmiste abil saab kindlaks teha võimalikke kõrvalekaldeid SM ennustustest, on t-kvark. T-kvark on raskeim avastatud elementaarosake ja laguneb seetõttu erinevalt teistest kvarkidest enne liitosakeste hadronite moodustamist, võimaldades erandlikult uurida paljast kvarki. Oma massi tõttu on t-kvark ka osake, mis omab kõige tugevamat vastasmõju Higgsi bosoniga. T-kvargid saavad tekkida kas kvargi- ja antikvargi paaridena tugeva vastastikmõju abil või väiksemal määral üksikute (anti)kvarkidena nõrga vastastikmõju kaudu. Seda tõenäosust, et vastav protsess aset leiab, iseloomustab tekkeristlõige, mis on kõigi osakestefüüsika protsesside oluliseks omaduseks. Üksikute t-kvarkide teket vaadeldi esmakordselt alles 2009. aastal, samas on nende abil võimalik uurida mitmeid t-kvarkide omadusi paremini kui t-kvargi paaride abil. Näiteks ei jõua t-kvargi spinn enne lagunemist muutuda ja seetõttu saab seda üksiku t-kvargi laguproduktide kaudu mõõta, kusjuures SM ennustab, et kõik tekkinud üksikud t-kvargid peaksid olema vasakukäelised. Suur Hadronite Põrguti (LHC) on 27 km pikkune maailma suurim ja kõrgeima energiaga osakeste kiirendi, kus põrgatatakse vastassuundades liikuvaid prootonite kimpe masskeskme energiatel kuni 14 TeV. LHC-s tegutseb seitse eksperimenti, antud töö kasutab üldotstarbelise detektori CMS-iga tehtud mõõtmisi. Doktoritöös on mõõdetud üksiku t-kvargi ristlõiked prootonite põrgetel masskeskme energiatel 7 TeV ja 8 TeV ning üksiku t-kvargi polarisatsioon energial 8 TeV.After the recent discovery of the Higgs boson, all particles predicted by the standard model of particle physics (SM) have been found. However, since many phenomena, such as dark matter or neutrino masses, are not explained by SM, there is reason to believe that it is not the final theory. A particularly interesting object of study to check for possible deviations from SM predictions is the top quark. Top quark is the heaviest discovered particle. Its very high mass causes the top quark to decay before forming hadrons in contrast to other quarks, which always form composite particles. Thus, the top quark gives us a special opportunity to study a bare quark. Due to its mass, the top quark is also the particle with the strongest interaction with the Higgs boson. Top quarks are created either in quark-antiquark pairs through the strong interaction or less frequently as single top (anti)quarks through weak interaction. The probability of being created is measured by production cross section, which is an important property of all particle physics processes. Despite the smaller production cross section, single top production offers possibilities to study some of the top quark properties in a better way compared to pair production. For example, all single top quarks are created left-handed according to SM prediction, and as the top quark decays before the spin has time to change, the spin of the top quark can be measured through the decay products. Single top quark production was first observed only recently, in 2009. The Large Hadron Collider (LHC) is the world’s biggest and highest energy particle collider with a circumference of 27 km, colliding beams of protons circulating in opposite directions at centre-of-mass energies up to 14 TeV. There are seven experiments in operation at the LHC, this work utilises the data collected with the general purpose detector Compact Muon Solenoid (CMS). In this thesis, the measurement of single top quark cross section is performed at proton-proton collisions at the centre-of-mass energies of 7 and 8 TeV, and single top quark polarisation is measured at 8 TeV

The Large Hadron–Electron Collider at the HL-LHC

Se incluye contenido parcial de los autores, (contiene más de 300 autores)The Large Hadron–Electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High-Luminosity Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron–proton and proton–proton operations. This report represents an update to the LHeC’s conceptual design report (CDR), published in 2012. It comprises new results on the parton structure of the proton and heavier nuclei, QCD dynamics, and electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics by extending the accessible kinematic range of lepton–nucleus scattering by several orders of magnitude. Due to its enhanced luminosity and large energy and the cleanliness of the final hadronic states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, this report contains a detailed updated design for the energy-recovery electron linac (ERL), including a new lattice, magnet and superconducting radio-frequency technology, and further components. Challenges of energy recovery are described, and the lower-energy, high-current, three-turn ERL facility, PERLE at Orsay, is presented, which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution, and calibration goals that arise from the Higgs and parton-density-function physics programmes. This paper also presents novel results for the Future Circular Collider in electron–hadron (FCC-eh) mode, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies

The Large Hadron-Electron Collider at the HL-LHC

The Large Hadron-Electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High-Luminosity Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron-proton and proton-proton operations. This report represents an update to the LHeC's conceptual design report (CDR), published in 2012. It comprises new results on the parton structure of the proton and heavier nuclei, QCD dynamics, and electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics by extending the accessible kinematic range of lepton-nucleus scattering by several orders of magnitude. Due to its enhanced luminosity and large energy and the cleanliness of the final hadronic states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, this report contains a detailed updated design for the energy-recovery electron linac (ERL), including a new lattice, magnet and superconducting radio-frequency technology, and further components. Challenges of energy recovery are described, and the lower-energy, high-current, three-turn ERL facility, PERLE at Orsay, is presented, which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution, and calibration goals that arise from the Higgs and parton-density-function physics programmes. This paper also presents novel results for the Future Circular Collider in electron-hadron (FCC-eh) mode, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies.Peer reviewe

SUPERVISED LEARNING FOR COMPLEX DATA

Supervised learning problems are commonly seen in a wide range of scientific fields such as medicine and neuroscience. Given data with predictors and responses, an important goal of supervised learning is to find the underlying relationship between predictors and responses for future prediction. In this dissertation, we propose three new supervised learning approaches for the analysis of complex data. For the first two projects, we focus on block-wise missing multi-modal data which contain samples with different modalities. In the first project, we study regression problems with multiple responses. We propose a new penalized method to predict multiple correlated responses jointly, using not only the information from block-wise missing predictors but also the correlation information among responses. In the second project, we study regression problems with censored outcomes. We propose a penalized Buckley-James method that can simultaneously handle block-wise missing covariates and censored outcomes. For the third project, we analyze data streams under reproducing kernel Hilbert spaces. Specifically, we develop a new supervised learning method to learn the underlying model with limited storage space, where the model may be non-stationary. We use a shrinkage parameter and a data sparsity constraint to balance the bias-variance tradeoff, and use random feature approximation to control the storage space.Doctor of Philosoph

Urban Informatics

This open access book is the first to systematically introduce the principles of urban informatics and its application to every aspect of the city that involves its functioning, control, management, and future planning. It introduces new models and tools being developed to understand and implement these technologies that enable cities to function more efficiently – to become ‘smart’ and ‘sustainable’. The smart city has quickly emerged as computers have become ever smaller to the point where they can be embedded into the very fabric of the city, as well as being central to new ways in which the population can communicate and act. When cities are wired in this way, they have the potential to become sentient and responsive, generating massive streams of ‘big’ data in real time as well as providing immense opportunities for extracting new forms of urban data through crowdsourcing. This book offers a comprehensive review of the methods that form the core of urban informatics from various kinds of urban remote sensing to new approaches to machine learning and statistical modelling. It provides a detailed technical introduction to the wide array of tools information scientists need to develop the key urban analytics that are fundamental to learning about the smart city, and it outlines ways in which these tools can be used to inform design and policy so that cities can become more efficient with a greater concern for environment and equity

Urban Informatics

This open access book is the first to systematically introduce the principles of urban informatics and its application to every aspect of the city that involves its functioning, control, management, and future planning. It introduces new models and tools being developed to understand and implement these technologies that enable cities to function more efficiently – to become ‘smart’ and ‘sustainable’. The smart city has quickly emerged as computers have become ever smaller to the point where they can be embedded into the very fabric of the city, as well as being central to new ways in which the population can communicate and act. When cities are wired in this way, they have the potential to become sentient and responsive, generating massive streams of ‘big’ data in real time as well as providing immense opportunities for extracting new forms of urban data through crowdsourcing. This book offers a comprehensive review of the methods that form the core of urban informatics from various kinds of urban remote sensing to new approaches to machine learning and statistical modelling. It provides a detailed technical introduction to the wide array of tools information scientists need to develop the key urban analytics that are fundamental to learning about the smart city, and it outlines ways in which these tools can be used to inform design and policy so that cities can become more efficient with a greater concern for environment and equity

Urban Informatics

This open access book is the first to systematically introduce the principles of urban informatics and its application to every aspect of the city that involves its functioning, control, management, and future planning. It introduces new models and tools being developed to understand and implement these technologies that enable cities to function more efficiently – to become ‘smart’ and ‘sustainable’. The smart city has quickly emerged as computers have become ever smaller to the point where they can be embedded into the very fabric of the city, as well as being central to new ways in which the population can communicate and act. When cities are wired in this way, they have the potential to become sentient and responsive, generating massive streams of ‘big’ data in real time as well as providing immense opportunities for extracting new forms of urban data through crowdsourcing. This book offers a comprehensive review of the methods that form the core of urban informatics from various kinds of urban remote sensing to new approaches to machine learning and statistical modelling. It provides a detailed technical introduction to the wide array of tools information scientists need to develop the key urban analytics that are fundamental to learning about the smart city, and it outlines ways in which these tools can be used to inform design and policy so that cities can become more efficient with a greater concern for environment and equity

Report from Working Group 3: Beyond the standard model physics at the HL-LHC and HE-LHC

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3$ ab$^{-1}$ of data taken at a centre-of-mass energy of 14 TeV, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15$ ab$^{-1}$ of data at a centre-of-mass energy of 27 TeV. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will, generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics