Author: Russ R. Laher
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
Measurement of the Inclusive Electron Cross-Section from Heavy-Flavour Decays and Search for Compressed Supersymmetric Scenarios with the ATLAS Experiment
Author: Moritz Backes
Publisher: Springer
ISBN: 331907136X
Category : Science
Languages : en
Pages : 268
Book Description
The first part of this thesis presents the measurement of the inclusive cross-section for electron production from heavy-flavour decays in the electron transverse momentum range 7 GeV
Publisher: Springer
ISBN: 331907136X
Category : Science
Languages : en
Pages : 268
Book Description
The first part of this thesis presents the measurement of the inclusive cross-section for electron production from heavy-flavour decays in the electron transverse momentum range 7 GeV
Updated Excitation and Ionization Cross Sections for Electron Impact on Atomic Oxygen
Author: Russ R. Laher
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
Bibliography of Low Energy Electron Collision Cross Section Data
Author: Lee Joseph Kieffer
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 98
Book Description
A bibliography of low energy electron collision cross section data is prese * nted.Only references which report original measurements or calculations of electron collision cross sections are included.The cross section data for each process are listed by atomic species in order of their atomic number.The data for molecules are listed in arbitrary order. (Author).
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 98
Book Description
A bibliography of low energy electron collision cross section data is prese * nted.Only references which report original measurements or calculations of electron collision cross sections are included.The cross section data for each process are listed by atomic species in order of their atomic number.The data for molecules are listed in arbitrary order. (Author).
Measurement of the Cross Section for the Reaction T + T [arrow] He4 + 2n + 11.4 Mev
Author:
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 8
Book Description
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 8
Book Description
Measurement of the Diphoton Differential Cross-section in P[bar P] Collisions at [square Root] S
Author: Joshua Marc Dyer
Publisher:
ISBN:
Category : Differential cross sections
Languages : en
Pages : 202
Book Description
Publisher:
ISBN:
Category : Differential cross sections
Languages : en
Pages : 202
Book Description
Estimation of Electron Impact Excitation Cross Sections of Molecular Hydrogen
Author: George M. Prok
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 44
Book Description
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 44
Book Description
Charged Particle Cross Sections
Author: Los Alamos Scientific Laboratory
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 470
Book Description
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 470
Book Description
Measurement of the TtH Production Cross-section with a Collimated H -> Bb Decay in Pp Collisions at Sqrt(s)
Author: Eftychia Tzovara
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The predictions of the Standard Model (SM) of particle physics have been probed with remarkable accuracy, so far. The Large Hadron Collider (LHC) at CERN has significantly contributed to this quest. A remarkable achievement of the ATLAS and CMS experiments at the LHC was the discovery of the Higgs boson in 2012, the last missing piece of the SM. With the increasing amount of proton-proton collisions delivered by the LHC, more precise measurements of the Higgs boson are now possible, while rare processes are accessible as well. A property of the Higgs boson that is of particular importance is its coupling to the top quark, which is expected to be the strongest in the SM due to the high mass of the top quark. Therefore, its precise measurement is a stringent test of the SM. A direct measurement of the top-quark Yukawa coupling can be assessed through the Higgs-boson production in association with a pair of top quarks (ttH). This thesis presents the measurement of the ttH process with a subsequent Higgs-boson decay to a pair of b-quarks (H -> bb), the decay mode with the largest branching ratio. The measurement is performed with data collected by the ATLAS detector, corresponding to an integrated luminosity of 139 fb^-1 at a center-of-mass energy of 13 TeV. Events with one or two charged leptons from the tt decay in the final state are considered to the measurement. The main challenge of the ttH(H -> bb) channel emerges from the large SM backgrounds from the production of top-quark pairs with additional jets (tt+jets). Also the many jets coming from b-hadrons (b-jets) in the final state cause combinatorial ambiguities. Thus, the identification of such jets is decisive in order to determine the signal and reject many background processes. The ttH events are split into exclusive analysis regions, based on the number of leptons, jets, and jets tagged as b-jets, providing regions enhanced in signal, or in the main background components. Specifically in the single-lepton channel, a boosted category is defined by selecting events in which the Higgs boson and possibly also the hadronically decaying top quark are produced with high transverse momentum (pT), with their decay products being collimated in large-radius jets. The single-lepton boosted channel targets events with Higgs-boson candidate pT >= 300 GeV and is the main scope of this thesis. To identify the reconstructed objects with the underlying particles and to maximise the discrimination of the ttH signal from the overwhelming tt+jets background events in the signal-enriched regions, machine-learning algorithms are employed. The background is dominated by a tt process with an additional gluon in the final state which further splits into a pair of b-quarks (tt+bb). Besides, a large number of heavy-flavour jets in the final state is not well modelled, thus many systematic uncertainties have to be considered, decreasing the sensitivity of the measurement. All the defined analysis regions are analysed together in a combined profile likelihood fit to test for the presence of signal. The fit simultaneously determines the event yields for the signal and the most important background component, while constraining the overall background model within the assigned systematic uncertainties. Eventually, the ratio of the measured ttH cross section to the SM expectation in the inclusive cross-section measurement is found to be 0.35 +0.36,-0.34}, corresponding to an observed (expected) significance of 1.0 (2.7) standard deviations. A ttH signal strength larger than the SM prediction is excluded at 95% confidence level. The measurement uncertainty is dominated by systematic uncertainties, mainly regarding the theoretical knowledge of the tt +>= 1b background process. Finally, to further test the SM, the cross-section is measured differentially as a function of the generator-level Higgs-boson pT, taking advantage of the reconstruction of the Higgs-boson kinematics.
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The predictions of the Standard Model (SM) of particle physics have been probed with remarkable accuracy, so far. The Large Hadron Collider (LHC) at CERN has significantly contributed to this quest. A remarkable achievement of the ATLAS and CMS experiments at the LHC was the discovery of the Higgs boson in 2012, the last missing piece of the SM. With the increasing amount of proton-proton collisions delivered by the LHC, more precise measurements of the Higgs boson are now possible, while rare processes are accessible as well. A property of the Higgs boson that is of particular importance is its coupling to the top quark, which is expected to be the strongest in the SM due to the high mass of the top quark. Therefore, its precise measurement is a stringent test of the SM. A direct measurement of the top-quark Yukawa coupling can be assessed through the Higgs-boson production in association with a pair of top quarks (ttH). This thesis presents the measurement of the ttH process with a subsequent Higgs-boson decay to a pair of b-quarks (H -> bb), the decay mode with the largest branching ratio. The measurement is performed with data collected by the ATLAS detector, corresponding to an integrated luminosity of 139 fb^-1 at a center-of-mass energy of 13 TeV. Events with one or two charged leptons from the tt decay in the final state are considered to the measurement. The main challenge of the ttH(H -> bb) channel emerges from the large SM backgrounds from the production of top-quark pairs with additional jets (tt+jets). Also the many jets coming from b-hadrons (b-jets) in the final state cause combinatorial ambiguities. Thus, the identification of such jets is decisive in order to determine the signal and reject many background processes. The ttH events are split into exclusive analysis regions, based on the number of leptons, jets, and jets tagged as b-jets, providing regions enhanced in signal, or in the main background components. Specifically in the single-lepton channel, a boosted category is defined by selecting events in which the Higgs boson and possibly also the hadronically decaying top quark are produced with high transverse momentum (pT), with their decay products being collimated in large-radius jets. The single-lepton boosted channel targets events with Higgs-boson candidate pT >= 300 GeV and is the main scope of this thesis. To identify the reconstructed objects with the underlying particles and to maximise the discrimination of the ttH signal from the overwhelming tt+jets background events in the signal-enriched regions, machine-learning algorithms are employed. The background is dominated by a tt process with an additional gluon in the final state which further splits into a pair of b-quarks (tt+bb). Besides, a large number of heavy-flavour jets in the final state is not well modelled, thus many systematic uncertainties have to be considered, decreasing the sensitivity of the measurement. All the defined analysis regions are analysed together in a combined profile likelihood fit to test for the presence of signal. The fit simultaneously determines the event yields for the signal and the most important background component, while constraining the overall background model within the assigned systematic uncertainties. Eventually, the ratio of the measured ttH cross section to the SM expectation in the inclusive cross-section measurement is found to be 0.35 +0.36,-0.34}, corresponding to an observed (expected) significance of 1.0 (2.7) standard deviations. A ttH signal strength larger than the SM prediction is excluded at 95% confidence level. The measurement uncertainty is dominated by systematic uncertainties, mainly regarding the theoretical knowledge of the tt +>= 1b background process. Finally, to further test the SM, the cross-section is measured differentially as a function of the generator-level Higgs-boson pT, taking advantage of the reconstruction of the Higgs-boson kinematics.
New Technique for Measuring Photonuclear Cross Sections and Its Application to the Cu63([gamma], N)Cu62 and C12([gamma], N)C11 Reactions
Author: Lester L. Newkirk
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 60
Book Description
Publisher:
ISBN:
Category : Cross sections (Nuclear physics)
Languages : en
Pages : 60
Book Description
Total and Differential [pi-pi] Cross Sections in [pi-rho] Interactions at 1.25 Bev/c
Author: D. Duane Carmony
Publisher:
ISBN:
Category : Differential cross sections
Languages : en
Pages : 12
Book Description
Publisher:
ISBN:
Category : Differential cross sections
Languages : en
Pages : 12
Book Description