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Studium difrakčních procesů na experimentu ATLAS
Kůs, Vlastimil ; Taševský, Marek (advisor) ; Valkárová, Alice (referee)
The chapter of forward and diraction physics is an indispensable and always a rich part of the physics menu of any experiment at high-energy accelerators. In last years, a big eort was put to study and estimate the feasibility or a discovery potential of Higgs boson produced in the central exclusive diraction events at LHC. These processes have a chance to become competitive or complementary to the program of the Higgs boson search in standard (non-diraction) processes, in particular in the supersymmetric extension of the Standard model. In this thesis an analysis of the central exclusive production of Higgs boson decaying to two tau leptons is performed, along with investigations of corresponding background processes.
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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 diffractive processes at the ATLAS Experiment
Kůs, Vlastimil ; Taševský, Marek (advisor) ; Royon, Christophe (referee) ; Valkárová, Alice (referee)
Title: Study of diffractive processes at the ATLAS Experiment Author: Vlastimil Kůs Department: Institute of Particle and Nuclear Physics Supervisor: Mgr. Marek Taševský, Ph.D. Institute of Physics of the Academy of Sciences of the CR, v.v.i. Abstract: A data sample of pp collisions corresponding to an integrated lumi- nosity of 6.75 nb−1 was collected at √ s = 7 TeV using the ATLAS detector at the Large Hadron Collider. Collision events with at least two jets with pT > 20 GeV are used to measure the differential cross section of the diffractive dijet production as a function of the rapidity gap size ∆ηF , the largest forward region extending from |η| = 4.8 devoid of particle activity above threshold momentum cuts, and an estimator of the fractional momentum loss of the scattered proton assuming the single diffractive dissociation (pp → pX), ˜ξ± . Comparisons with various Monte Carlo models reveal that though the region of small ˜ξ± and large rapidity gaps is dominated by diffraction, a contribution form non-diffractive events cannot be neglected. The rapidity gap survival probability is estimated based on data to Monte Carlo comparisons in the −3.2 < log10 ˜ξ± < −2.5 region of the ˜ξ± distri- bution with the ∆ηF > 2 requirement. 1
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Measurement of Diffractive Dijet Production in Deep Inelastic Scattering at HERA Collider
Pokorný, Boris ; Valkárová, Alice (advisor) ; Kupčo, Alexander (referee) ; Leitner, Rupert (referee)
The diffractive production of two jets in deep inelastic e± p scattering is mea- sured in the kinematic region of photon virtuality 4 < Q2 < 80 GeV2 , inelasticity 0.1 < y < 0.7, momentum fraction xIP < 0.03, proton ver- tex momentum transfer |t| < 1 and mass of a dissociative baryonic system MY < 1.6 GeV. Diffractive events are identified with the large rapidity gap technique. Integrated and single differential cross sections are measured for jets of transverse momenta p∗ T1 > 5.5 GeV and p∗ T2 > 4.0 GeV and pseudora- pidities −3 < η∗ 1,2 < 0. The data were collected by the H1 experiment at the HERA collider in years 2005-2007, corresponding to an integrated luminosity of 283.7 pb−1 . The measurements are compared with NLO predictions based on the DGLAP parton evolution.
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Studium difrakčních ep interakcí na hadron-elektronovém collideru
Jansová, Markéta ; Valkárová, Alice (advisor) ; Žáček, Josef (referee)
A new ep collider LHeC is currently planned at CERN. LHeC should comple- ment the physics program of former ep collider HERA and existing hadron-hadron collider LHC. In the LHeC project the collisions of electrons with energy 60 GeV and protons with energy 7 TeV should be studied. The thesis is focused on the study of diffractive charged current deep inelastic scattering interactions, which had already been investigated at HERA collider (H1 experiment), but with un- satisfying statistics. This thesis reproduce Monte Carlo predictions obtained by H1 collaboration for this process and its main goal is calculation of diffractive charged current DIS cross section for future LHeC project.
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Elastic Scattering at the LHC
Kašpar, Jan ; Kundrát, Vojtěch (advisor) ; Valkárová, Alice (referee) ; Kupčo, Alexander (referee)
Title: Elastic scattering at the LHC Author: Jan Kasˇpar Departement: Institute of Particle and Nuclear Physics Supervisor of the thesis: RNDr. Vojtečh Kundra't, DrSc., Institute of Physics AS CR Abstract: The seemingly simple elastic scattering of protons still presents a challenge for the theory. In this thesis we discuss the elastic scattering from theoretical as well as experimental point of view. In the theory part, we present several mod- els and their predictions for the LHC. We also discuss the Coulomb-hadronic interference, where we present a new eikonal calculation to all orders of α, the fine-structure constant. In the experimental part we introduce the TOTEM experiment which is dedicated, among other subjects, to the measurement of the elastic scattering at the LHC. This measurement is performed primarily with the Roman Pot (RP) detectors - movable beam-pipe insertions hundreds of meters from the interaction point, that can detect protons scattered to very small angles. We discuss some aspects of the RP simulation and reconstruc- tion software. A central point is devoted to the techniques of RP alignment - determining the RP sensor positions relative to each other and to the beam. At the end we present the analysis of TOTEM's first elastic scattering mea- surement at the LHC. The resulting...
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