|
|
Measurement of the top quark properties
Schovancová, Jaroslava ; Chudoba, Jiří (advisor) ; Davídek, Tomáš (referee) ; Filipčič, Andrej (referee)
Title: Measurement of the top quark properties Author: Mgr. Jaroslava Schovancová Department: Institute of Physics, Academy of Sciences of the Czech Re- public Supervisor: RNDr. Jiří Chudoba, Ph.D., Institute of Physics, Academy of Sciences of the Czech Republic Abstract: This Thesis presents the ATLAS experiment measurement of the top quark differential cross-section as a function of pT, mass and rapidity of the t¯t system. A sample of approx. 4.7 fb−1 of the 2011 pp collision data at the center-of-mass energy of 7 TeV was analyzed. The differential spectra shapes in the t¯t system are consistent with the Standard Model and reason- ably described by the event generators. Several activities in the scope of ATLAS Distributed Computing are pre- sented, particularly in the area of operations, monitoring, automation, and development of the PanDA Workload Management System. Such activities aim to improve efficiency and facilitate the use of distributed computing re- sources and therefore contribute in supporting the ATLAS Physics Program. Keywords: ATLAS, top quark, differential cross-section, missing transverse energy, ATLAS Distributed Computing
|
|
|
Cross-section measurements of the Higgs boson decaying into a pair of tau leptons with the ATLAS detector
Mlynáriková, Michaela ; Davídek, Tomáš (advisor) ; Hubáček, Zdeněk (referee) ; Šumbera, Michal (referee)
The ATLAS experiment is one of the two general-purpose detectors at the Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) in Switzerland. ATLAS is designed for precision mea- surements of particle properties, the search of the Higgs boson and new physics beyond the Standard Model. The experiment got worldwide atten- tion in 2012, when after the collaborative efforts with the CMS experiment the Higgs boson discovery was announced. After the discovery, the preci- sion measurements of its properties became one of the main objectives of the LHC physics programme, since a potential observation of deviations from the Standard Model predictions might lead to the discovery of new physics. In this thesis, the measurements of the Higgs boson production cross-sections in the H → ττ decay channel are presented. Based on the proton-proton collision data collected at the centre-of-mass energy of 13 TeV in years 2015 and 2016, the signal over the expected background from the other Standard Model processes is established with the observed significance of 4.4σ. Com- bined with the data collected at 7 and 8 TeV, the observed signal significance amounts to 6.4σ, which constitutes a single experiment observation of the H → ττ decays by ATLAS. All presented results are found to be consistent with...
|
|
| |
|
|
Cosmic ray showers with anomalous longitudinal profile
Blažek, Jiří ; Trávníček, Petr (advisor) ; Davídek, Tomáš (referee)
Title: Cosmic Ray Showers with Anomalous Longitudinal Profile Author: Jiří Blažek Department: Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University Supervisor: RNDr. Petr Trávníček, Ph.D., Institute of Physics ASCR Abstract: The aim of this work was to study high-energy cosmic ray showers with anomalous longitudinal profiles generated by Monte-Carlo simulation and subse- quently use the acquired analysis techniques on results from the Pierre Auger Observatory (PAO) in Argentina. Firstly, a short introduction of various de- scriptions of the extensive air showers was given. Then a systematic analysis was performed on approx. 7 × 105 simulated showers with three different tech- niques. A brief explanation of the functionality of the PAO was given, then the importance of monitoring the immediate state of the atmosphere using the Shoot- the-Shower program was elucidated and the FRAM telescope was described in detail. FRAM enabled an identification of showers with a clear atmospheric back- ground, this sample of showers was then analyzed and several interesting events warranting a further study were chosen. Keywords: Pierre Auger Observatory, Extensive Air Showers, Chemical Compo- sition, Anomalous Longitudinal Profile, Gaisser-Hillas Function
|
|
|
Study of fake-tau background with the ATLAS experiment
Martinovicová, Gabriela ; Pleskot, Vojtěch (advisor) ; Davídek, Tomáš (referee)
Title: Study of fake-tau background with the ATLAS experiment Author: Gabriela Martinovicová Institute: Institute of Particle and Nuclear Physics Supervisor: Mgr. Vojtěch Pleskot, Ph.D., Institute of Particle and Nuclear Physics Abstract: The τ-leptons are the important final-state components, not only in the Standard Model processes but also in the processes beyond the Standard Model studied at the ATLAS experiment at CERN. They are characterized by mostly decaying into hadrons with one or three charged particles and, in most cases, with at least one neutral pion in the final-state. Due to their short decay length, only their decay products are observed in the detector. Jets naturally fake hadronically decaying τ leptons, so it is necessary to estimate such a fake-τ background. The Fake Factor method uses a correction factor, called fake factor (FF), measured from the data and applied to the data to estimate the fake-τ background in a given signal region. One of the complications is that FF differs for τ candidates faked by jets derived from quarks or gluons and thus must be measured in the control region with the same fraction of quark jets as in the signal region. The solution to this problem is the universal FF method, which proposed that from the FFs measured in samples with a large difference in the...
|
|
|
Tile Calorimeter testbeam data analysis
Uhliarová, Lea ; Davídek, Tomáš (advisor) ; Dolejší, Jiří (referee)
Tile Calorimeter modules are regularly tested in the CERN SPS North Area, as they are an integral part of the ATLAS experiment at the Large Hadron Collider at CERN. In this thesis, test beam data from November 2018 were used for two separate analyses. Muon SPS H8 beam allowed for the review of radial electromagnetic cali- bration in the extended barrel module EBC65. Data from November 2018 test beam confirmed the correctness of previously established and used constants for rectifying uneven response in A, BC and D cell rows. In the second analysis, hadron beam from the SPS accelerator impinging on the Tile Calorimeter modules in the projective geometry was utilized. It served to determine the distribution of the mean energy in the calorimeter for hadronic showers in Tile Calorimeter at η varying from −0.05 up to −0.65. 1
|
|
|
Tine calibration of the ATLAS Tile Calorimeter using jets
Poláček, Stanislav ; Davídek, Tomáš (advisor) ; Rybář, Martin (referee)
The ATLAS experiment is one of the two general-purpose detectors at the Large Hadron Collider at CERN near Geneva. The goals of this particle physics experiment are the search for new physics phenomena and precision measurement of the particle interactions. Tilecal is the central hadronic calorimeter of the ATLAS. The calorimeter time calibration is important for the time-of-flight measurement of particles (used in some analyses) as well as for the actual energy reconstruction. 1
|
|
|
Study of B-meson decays in the Belle experiment
Krištof, Michal ; Doležal, Zdeněk (advisor) ; Davídek, Tomáš (referee)
In the thesis we study the decay of B0 meson to D∗ s and ρ mesons. The thesis explains the methods and approaches to data analysis in so-called B-factories, simmilar to the KEKB accelerator. The aim of this thesis is to calculate the branching fraction of this decay to further improve the previously measured branching ratio at BaBar experiment with additional data gained from an ex- periment with higher integrated luminosity. This thesis's prospect is not only broadening our knowledge of branching fractions of B0 meson decays, but also it is a starting point for further analysis with the goal of broadening our knowl- edge of CP symmetry violation in the Standard Model by measuring angles of the Unitary Triangle. 1
|
|
|
Cross-section measurements of the Higgs boson decaying into a pair of tau leptons with the ATLAS detector
Mlynáriková, Michaela ; Davídek, Tomáš (advisor) ; Hubáček, Zdeněk (referee) ; Šumbera, Michal (referee)
The ATLAS experiment is one of the two general-purpose detectors at the Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) in Switzerland. ATLAS is designed for precision mea- surements of particle properties, the search of the Higgs boson and new physics beyond the Standard Model. The experiment got worldwide atten- tion in 2012, when after the collaborative efforts with the CMS experiment the Higgs boson discovery was announced. After the discovery, the preci- sion measurements of its properties became one of the main objectives of the LHC physics programme, since a potential observation of deviations from the Standard Model predictions might lead to the discovery of new physics. In this thesis, the measurements of the Higgs boson production cross-sections in the H → ττ decay channel are presented. Based on the proton-proton collision data collected at the centre-of-mass energy of 13 TeV in years 2015 and 2016, the signal over the expected background from the other Standard Model processes is established with the observed significance of 4.4σ. Com- bined with the data collected at 7 and 8 TeV, the observed signal significance amounts to 6.4σ, which constitutes a single experiment observation of the H → ττ decays by ATLAS. All presented results are found to be consistent with...
|
|
|
Response of the ATLAS Tile Calorimeter
Adámek, Tomáš ; Davídek, Tomáš (advisor) ; Faltová, Jana (referee)
TileCal is the Hadronic calorimeter covering the most central region of the ATLAS experiment which is one of the four major experiments at the Large Hadron Collider (LHC) at CERN. Main area of interest of this bachelor thesis is to examine the energy response and resolution of tested modules to electrons. Furthermore, the goal of this work is to make correction to the energy response with respect to the periodic structure of TileCal's cell.
|
guest ::
