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Jets in Heavy Ion Collisions at the ATLAS Detector
Spousta, Martin ; Dolejší, Jiří (advisor) ; Chýla, Jiří (referee) ; Bielčíková, Jana (referee)
After some introduction to the quantum chromodynamics and physics of the heavy ions collisions, and after a brief review of the ATLAS detector, the attention is focused to the main aim of the work. The main aim of the work is to develop and test algorithms suitable for the jet reconstruction in heavy ion collisions at the ATLAS detector. After the detailed description of these algorithms and their implementation to the official software of the ATLAS detector, the author analyzes their performance and provides expectation of accuracy of jet measurements in the heavy ion collisions. The rest of the work focuses on a possibility to study the influence of jets by the medium created in heavy ion collisions.
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Study of ambiguities of Quantum Chromodynamics predictions in hard processes
Posolda, Petr ; Chýla, Jiří (advisor) ; Dolejší, Jiří (referee) ; Rameš, Jiří (referee)
The thesis is devoted to phenomenological investigation of ambiguities of QCD predictions coming from renormalization and factorization procedures. We studied predictions for e+ e− annihilation and jet production in proton-proton collisions. In the former case, we analyzed the dependence on RS up to fourth order at low and high energy region. We particularly focused on the Principle of Minimal Sensitivity as a guide for optimal choice of renormalization scheme. It is shown that a proper choice of RS is important especially at low energies where for example commonly used MS RS implies negative and unstable predictions, and that PMS optimized result don't suffer any of these drawbacks at studied cases. In the second part of the thesis, the dependence of NLO jet cross-section on renormalization and factorization scales is studied for total energy 1.8, 7 and 14 TeV. It is shown that PMS again provides qualitatively reasonable and stable results and seems to be relevant also for processes with hadrons in initial state. 1
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Jet Production in p+p and d+Au Collisions √sNN = 200 GeV in STAR
Kapitán, Jan ; Šumbera, Michal (advisor) ; Chýla, Jiří (referee) ; Dolejší, Jiří (referee)
Title: Jet production in p+p and d+Au collisions at √ sNN = 200 GeV in STAR Author: Jan Kapitán Affiliation: Nuclear Physics Institute AS CR Supervisor: doc. Michal Šumbera, CSc., DSc., Nuclear Physics Institute AS CR Abstract: The aim of this work is to measure the effects of cold nuclear matter on jet production in √ sNN = 200 GeV d+Au collisions at Relativistic Heavy Ion Collider (RHIC). After a brief theoretical introduction and description of the experimental setup, jet analysis and the required corrections are described. The jets are reconstructed in p+p and d+Au collisions recorded by the STAR experiment using the anti − kT jet algorithm. Inclusive jet pT spectra in d+Au collisions and their centrality dependence are compared to the reference measurement in p+p collisions and to the binary collision scaling. Di-jet correlations are studied in p+p and most central d+Au collisions to measure the kT effect and its possible nuclear broadening. These results will also be used as a baseline measurement for ongoing studies of jet production in heavy-ion collisions at RHIC. Keywords: jets, d+Au collisions, cold nuclear matter effects, STAR, RHIC
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Diffractive Dijet Production with Leading Proton in ep Collisions at HERA.
Žlebčík, Radek ; Valkárová, Alice (advisor) ; Chýla, Jiří (referee) ; Levonian, Sergey (referee)
The cross section of the diffractive process e+p → e+Xp is measured at a centre-of-mass energies of 319 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction defined by photon virtualities Q2 < 2 GeV2 and in deep-inelastic scattering with 4 GeV2 < Q2 < 80 GeV2 . The results are compared to next-to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep- inelastic scattering. A collinear QCD factorization theorem is tested against the measured cross sections and their ratios. 1
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Study of ambiguities of Quantum Chromodynamics predictions in hard processes
Posolda, Petr ; Chýla, Jiří (advisor) ; Dolejší, Jiří (referee) ; Rameš, Jiří (referee)
The thesis is devoted to phenomenological investigation of ambiguities of QCD predictions coming from renormalization and factorization procedures. We studied predictions for e+ e− annihilation and jet production in proton-proton collisions. In the former case, we analyzed the dependence on RS up to fourth order at low and high energy region. We particularly focused on the Principle of Minimal Sensitivity as a guide for optimal choice of renormalization scheme. It is shown that a proper choice of RS is important especially at low energies where for example commonly used MS RS implies negative and unstable predictions, and that PMS optimized result don't suffer any of these drawbacks at studied cases. In the second part of the thesis, the dependence of NLO jet cross-section on renormalization and factorization scales is studied for total energy 1.8, 7 and 14 TeV. It is shown that PMS again provides qualitatively reasonable and stable results and seems to be relevant also for processes with hadrons in initial state. 1
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Investigation of the factorization scheme dependence of finite order perturbative QCD calculations
Kolář, Karel ; Chýla, Jiří (advisor) ; Rameš, Jiří (referee) ; Formánek, Jiří (referee)
Title: Investigation of the factorization scheme dependence of finite order per- turbative QCD calculations Author: Karel Kolář Institute: Institute of Particle and Nuclear Physics Supervisor of the doctoral thesis: prof. Jiří Chýla, CSc., Institute of Physics of the Academy of Sciences of the Czech Republic Abstract: The main aim of this thesis is the investigation of phenomenological implications of the freedom in the choice of the factorization scheme for the de- scription of hard collisions with the potential application for an improvement of current NLO Monte Carlo event generators. We analyze the freedom associated with the definition of parton distribution functions and we derive general formu- lae governing the dependence of parton distribution functions and hard scattering cross-sections on unphysical quantities specifying the renormalization and factor- ization procedure. The issue of the specification of factorization schemes via the corresponding higher order splitting functions is discussed in detail. The main attention is paid to the so called ZERO factorization scheme, which allows the construction of consistent NLO Monte Carlo event generators in which initial state parton showers can be taken formally at the LO. Unfortunately, it has turned out that the practical applicability of the ZERO...
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Jet Production in p+p and d+Au Collisions √sNN = 200 GeV in STAR
Kapitán, Jan ; Šumbera, Michal (advisor) ; Chýla, Jiří (referee) ; Dolejší, Jiří (referee)
Title: Jet production in p+p and d+Au collisions at √ sNN = 200 GeV in STAR Author: Jan Kapitán Affiliation: Nuclear Physics Institute AS CR Supervisor: doc. Michal Šumbera, CSc., DSc., Nuclear Physics Institute AS CR Abstract: The aim of this work is to measure the effects of cold nuclear matter on jet production in √ sNN = 200 GeV d+Au collisions at Relativistic Heavy Ion Collider (RHIC). After a brief theoretical introduction and description of the experimental setup, jet analysis and the required corrections are described. The jets are reconstructed in p+p and d+Au collisions recorded by the STAR experiment using the anti − kT jet algorithm. Inclusive jet pT spectra in d+Au collisions and their centrality dependence are compared to the reference measurement in p+p collisions and to the binary collision scaling. Di-jet correlations are studied in p+p and most central d+Au collisions to measure the kT effect and its possible nuclear broadening. These results will also be used as a baseline measurement for ongoing studies of jet production in heavy-ion collisions at RHIC. Keywords: jets, d+Au collisions, cold nuclear matter effects, STAR, RHIC
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Jets in Heavy Ion Collisions at the ATLAS Detector
Spousta, Martin ; Dolejší, Jiří (advisor) ; Chýla, Jiří (referee) ; Bielčíková, Jana (referee)
After some introduction to the quantum chromodynamics and physics of the heavy ions collisions, and after a brief review of the ATLAS detector, the attention is focused to the main aim of the work. The main aim of the work is to develop and test algorithms suitable for the jet reconstruction in heavy ion collisions at the ATLAS detector. After the detailed description of these algorithms and their implementation to the official software of the ATLAS detector, the author analyzes their performance and provides expectation of accuracy of jet measurements in the heavy ion collisions. The rest of the work focuses on a possibility to study the influence of jets by the medium created in heavy ion collisions.
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