|
|
Studies of Higgs boson in its decay to a pair of tau-leptons and search for excited tau-lepton with the ATLAS detector
Mihule, Kristina ; Davídek, Tomáš (advisor) ; Kvita, Jiří (referee) ; Lysák, Roman (referee)
The Standard Model (SM) describes known elementary particles and their interactions. The ATLAS experiment is located at the Large Hadron Collider (LHC) in CERN (Geneva). The ATLAS detector measures data from proton- proton collisions at high centre-of-mass energy. The collected data allow physi- cists to precisely study SM and look for evidence of particles beyond the Stan- dard Model. The presented thesis describes the analysis of Higgs boson decay to a pair of tau-leptons. The measurement of the Higgs boson production cross section is based on the data set collected by the ATLAS detector in proton-proton (pp) collisions at a centre-of-mass energy of 13 TeV in the years 2015-18 (so-called Run 2). This dissertation presents the update of the algorithm of Higgs boson mass reconstruction for the Run 2 ATLAS conditions. The evaluation of fake tau-lepton background is also discussed. Further, this dissertation is dedicated to the search for excited tau-leptons in the Run 2 ATLAS data set. Contact interaction of the excited tau-leptons is assumed, which would occur if fermions were composite rather than elemen- tary. The analysed ATLAS data from pp collisions in Run 2 set do not contain signatures of excited tau-leptons production. Within the considered model with the compositeness scale Λ = 10 TeV, the upper...
|
|
|
Studium kinematiky rozpadů top-antitopových párů v experimentu Atlas
Berta, Peter ; Kvita, Jiří (advisor) ; Soustružník, Karel (referee)
In this thesis, I deal with the measurement of the transverse momentum spectrum of the top quark produced in top-antitop pairs at the LHC at center of mass energy 7 TeV. The analysis is carried out within the ATLAS collaboration. In the single lepton decay channel, I have performed studies on the simulation which were necessary to obtain the final spectrum from real data. I describe basic event selection rules to reduce background events. I study the efficiency of top-antitop pairs reconstruction. I study the unfolding of the measured spectrum which corrects for effects caused by imperfect resolutions. At the end, I show the measured top quark transverse momentum spectrum obtained from my analysis.
|
|
| |
|
|
Top Quark Physics with the ATLAS Detector
Slovák, Radim ; Kvita, Jiří (advisor) ; Soustružník, Karel (referee)
In the presented diploma thesis we study the reconstruction of the top antitop system in proton-proton colisions with central mass energy 7 TeV de- livered by LHC accelerator at CERN to the ATLAS experiment. ALPGEN and MC@NLO generators are described as two main method of top antitop pairs simulations. We compare events simulated by generators to data from LHC. The background and selection criteria are summarized. Next we de- scribed various methods of the top antitop reconstruction. Finally the Z particle was also studied. 1
|
|
|
The Belle II vertex detector alignment studies and prompt sin 2 phi analysis
Kandra, Jakub ; Doležal, Zdeněk (advisor) ; Kvita, Jiří (referee) ; Marčišovský, Michal (referee)
This thesis is focused on the alignment studies of the vertex detector during first years of the Belle II detector operation and the first prompt sin 2ϕ1 analysis using the first rel- evant data collected by the detector. Firstly, the Belle II detector and the SuperKEKB accelerator is introduced. Secondly, the software framework and tools operation is ex- plained, then the alignment procedure and developed validation procedures are described in detail. Fourth section reports about the first years of the detector operation. Next three sections are related to different alignment studies during thee different periods of the vertex detector operation: the Phase 2, VXD Commissioning and beginning of the Phase 3 early. The last section covers the time-dependent CP Violation and mixing measurements performed using the data collected prior to the 11en of May 2020. 1
|
|
|
Angular analysis of the B0 to K* mu mu decay with the ATLAS detector
Carli, Ina ; Doležal, Zdeněk (advisor) ; Kvita, Jiří (referee) ; Kreps, Michal (referee)
An angular analysis of the rare decay B0 → K∗ (K+ π− )µ+ µ− is presented. The study is based on a data sample from pp collisions at centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the Large Hadron Collider which corresponds to an integrated luminosity of 20.3 fb−1 . An extended unbinned maximum-likelihood fit of the decay angular distribution is used to measure the CP-averaged angular observables FL, S3, S4, S5, S7 and S8 and the cor- responding form-factor independent observables P1, P4, P5, P6 and P8. The measurements are performed in the region 0.04 GeV2 < q2 < 6 GeV2 , where q is the dimuon invariant mass. The results are in agreement with the Standard Model predictions and com- patible with measurements published by other experiments. The most signifi- cant deviations are observed for parameters P4, P5 at the level of 2.7 standard deviations and for P8 which is 1.9 standard deviations away from one of the predictions. The P5 deviation in bin 4 GeV2 < q2 < 6 GeV2 is consistent with the one reported by the LHCb collaboration. The second part of this work shortly summarises the operation of the ATLAS Semiconductor Tracker, testing of the prototype module for the Inner Tracker strip upgrade, and the monitoring of non-collision background which was devel- oped as a part of this thesis.
|
|
|
Top Quark Physics with the ATLAS Detector
Slovák, Radim ; Kvita, Jiří (advisor) ; Soustružník, Karel (referee)
In the presented diploma thesis we study the reconstruction of the top antitop system in proton-proton colisions with central mass energy 7 TeV de- livered by LHC accelerator at CERN to the ATLAS experiment. ALPGEN and MC@NLO generators are described as two main method of top antitop pairs simulations. We compare events simulated by generators to data from LHC. The background and selection criteria are summarized. Next we de- scribed various methods of the top antitop reconstruction. Finally the Z particle was also studied. 1
|
|
|
Studium kinematiky rozpadů top-antitopových párů v experimentu Atlas
Berta, Peter ; Kvita, Jiří (advisor) ; Soustružník, Karel (referee)
In this thesis, I deal with the measurement of the transverse momentum spectrum of the top quark produced in top-antitop pairs at the LHC at center of mass energy 7 TeV. The analysis is carried out within the ATLAS collaboration. In the single lepton decay channel, I have performed studies on the simulation which were necessary to obtain the final spectrum from real data. I describe basic event selection rules to reduce background events. I study the efficiency of top-antitop pairs reconstruction. I study the unfolding of the measured spectrum which corrects for effects caused by imperfect resolutions. At the end, I show the measured top quark transverse momentum spectrum obtained from my analysis.
|
|
| |
guest ::
RSS feed.