Author: Steve R. Blattnig
Publisher:
ISBN:
Category : Particles (Nuclear physics)
Languages : en
Pages : 88
Book Description
Parameterized Cross Sections for Pion Production in Proton-Proton Collisions
Author: Steve R. Blattnig
Publisher:
ISBN:
Category : Particles (Nuclear physics)
Languages : en
Pages : 88
Book Description
Publisher:
ISBN:
Category : Particles (Nuclear physics)
Languages : en
Pages : 88
Book Description
New Aspects of High-Energy Proton-Proton Collisions
Author: A. Ali
Publisher: Springer Science & Business Media
ISBN: 1461595401
Category : Science
Languages : en
Pages : 437
Book Description
Articles focus on the planned European proton-proton collider, and concentrate on physics issues, rather than the more technical concerns addressed in the three previous workshops. The use of energies much higher than those of the American Superconducting Super Collider is featured. Topics include reviews of current projects, hadron collisions, lep
Publisher: Springer Science & Business Media
ISBN: 1461595401
Category : Science
Languages : en
Pages : 437
Book Description
Articles focus on the planned European proton-proton collider, and concentrate on physics issues, rather than the more technical concerns addressed in the three previous workshops. The use of energies much higher than those of the American Superconducting Super Collider is featured. Topics include reviews of current projects, hadron collisions, lep
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.
Inclusive b Jet Production in Proton-Proton Collisions
Author: Patrick L.S. Connor
Publisher: Springer Nature
ISBN: 3030343839
Category : Science
Languages : en
Pages : 325
Book Description
^ 74 GeV and |y| 2.4; the b jets must contain a B hadron. The measurement has significant statistics up to p T ∼ O(TeV). Advanced methods of unfolding are performed to extract the signal. It is found that fixed-order calculations with underlying event describe the measurement well.
Publisher: Springer Nature
ISBN: 3030343839
Category : Science
Languages : en
Pages : 325
Book Description
^ 74 GeV and |y| 2.4; the b jets must contain a B hadron. The measurement has significant statistics up to p T ∼ O(TeV). Advanced methods of unfolding are performed to extract the signal. It is found that fixed-order calculations with underlying event describe the measurement well.
Inclusive b Jet Production in Proton-Proton Collisions
Author: Patrick L.S. Connor
Publisher: Springer
ISBN: 9783030343828
Category : Science
Languages : en
Pages : 309
Book Description
^ 74 GeV and |y| 2.4; the b jets must contain a B hadron. The measurement has significant statistics up to p T ∼ O(TeV). Advanced methods of unfolding are performed to extract the signal. It is found that fixed-order calculations with underlying event describe the measurement well.
Publisher: Springer
ISBN: 9783030343828
Category : Science
Languages : en
Pages : 309
Book Description
^ 74 GeV and |y| 2.4; the b jets must contain a B hadron. The measurement has significant statistics up to p T ∼ O(TeV). Advanced methods of unfolding are performed to extract the signal. It is found that fixed-order calculations with underlying event describe the measurement well.
Inclusive B Jet Production in Proton-Proton Collisions
Author: Patrick L.S. Connor
Publisher:
ISBN: 9783030343842
Category : Econophysics
Languages : en
Pages : 0
Book Description
A measurement of the double differential cross section for inclusive b jet production in proton-proton collisions as well as fraction of b jets in the inclusive jet production is presented as a function of the transverse momentum p T and the absolute rapidity.
Publisher:
ISBN: 9783030343842
Category : Econophysics
Languages : en
Pages : 0
Book Description
A measurement of the double differential cross section for inclusive b jet production in proton-proton collisions as well as fraction of b jets in the inclusive jet production is presented as a function of the transverse momentum p T and the absolute rapidity.
Parameterized Cross Sections for Pion Production in Proton-Proton Collisions
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781720657910
Category :
Languages : en
Pages : 86
Book Description
An accurate knowledge of cross sections for pion production in proton-proton collisions finds wide application in particle physics, astrophysics, cosmic ray physics, and space radiation problems, especially in situations where an incident proton is transported through some medium and knowledge of the output particle spectrum is required when given the input spectrum. In these cases, accurate parameterizations of the cross sections are desired. In this paper much of the experimental data are reviewed and compared with a wide variety of different cross section parameterizations. Therefore, parameterizations of neutral and charged pion cross sections are provided that give a very accurate description of the experimental data. Lorentz invariant differential cross sections, spectral distributions, and total cross section parameterizations are presented.Blattnig, Steve R. and Swaminathan, Sudha R. and Kruger, Adam T. and Ngom, Moussa and Norbury, John W. and Tripathi, R. K.Langley Research CenterPIONS; SCATTERING CROSS SECTIONS; PARTICLE PRODUCTION; PROTONS; PARTICLE COLLISIONS; PROTON-PROTON REACTIONS; SPECTRA; PARAMETERIZATION; EXTRATERRESTRIAL RADIATION; COSMIC RAYS; ASTROPHYSICS
Publisher: Createspace Independent Publishing Platform
ISBN: 9781720657910
Category :
Languages : en
Pages : 86
Book Description
An accurate knowledge of cross sections for pion production in proton-proton collisions finds wide application in particle physics, astrophysics, cosmic ray physics, and space radiation problems, especially in situations where an incident proton is transported through some medium and knowledge of the output particle spectrum is required when given the input spectrum. In these cases, accurate parameterizations of the cross sections are desired. In this paper much of the experimental data are reviewed and compared with a wide variety of different cross section parameterizations. Therefore, parameterizations of neutral and charged pion cross sections are provided that give a very accurate description of the experimental data. Lorentz invariant differential cross sections, spectral distributions, and total cross section parameterizations are presented.Blattnig, Steve R. and Swaminathan, Sudha R. and Kruger, Adam T. and Ngom, Moussa and Norbury, John W. and Tripathi, R. K.Langley Research CenterPIONS; SCATTERING CROSS SECTIONS; PARTICLE PRODUCTION; PROTONS; PARTICLE COLLISIONS; PROTON-PROTON REACTIONS; SPECTRA; PARAMETERIZATION; EXTRATERRESTRIAL RADIATION; COSMIC RAYS; ASTROPHYSICS
A Measurement of the T T_bar Production Cross Section in Proton-antiproton Collisions at Sqrt(s)
Author: Markus Klute
Publisher:
ISBN:
Category :
Languages : en
Pages : 161
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 161
Book Description
High Transverse Momentum Direct Photon Production at Fermilab Fixed-target Energies
Author: Leonard Apanasevich
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 674
Book Description
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 674
Book Description
Measurement of Ψ(2S) Production Cross-sections in Proton-proton Collisions at √s
Author: Roel Aaij
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description