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Book Measurement of 2S Production Cross sections in Proton proton Collisions at s

Download or read book Measurement of 2S Production Cross sections in Proton proton Collisions at s written by Roel Aaij and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Measurement of the TtH Production Cross section with a Collimated H Bb Decay in Pp Collisions at Sqrt s

Download or read book Measurement of the TtH Production Cross section with a Collimated H Bb Decay in Pp Collisions at Sqrt s written by Eftychia Tzovara and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Associated Production of W Charm in 13 TeV Proton Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton

Download or read book Associated Production of W Charm in 13 TeV Proton Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton written by Svenja Karen Pflitsch and published by Springer Nature. This book was released on 2020-08-18 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: The associated production of a W boson and a single charm quark (W+c) is the only process in proton-proton collisions that directly probes the strange quark content of the proton. In this thesis, W+charm production is measured in proton-proton collisions at the LHC at 13 TeV, as recorded by the Compact Muon Solenoid (CMS) experiment. The analysis focuses on the identification of W bosons in their leptonic decay to a muon and a neutrino and charm quarks are tagged via the full reconstruction of D*-Mesons. The measured cross sections of W+c production are used, in combination with other relevant CMS results and the most precise HERA DIS data, in a QCD analysis to determine the strange quark content of the proton. The resulting strange quark distribution and suppression, with respect to the other light sea quarks, are in good agreement with those obtained in neutrino scattering experiments and extend their kinematic reach.

Book Proton antiproton Collider Physics

Download or read book Proton antiproton Collider Physics written by G. Altarelli and published by World Scientific. This book was released on 1989 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reviews the physics studied at the CERN proton-antiproton collider during its first phase of operation, from the first physics run in 1981 to the last one at the end of 1985.The volume consists of a series of review articles written by physicists who are actively involved with the collider research program. The first article describes the proton-antiproton collider facility itself, including the antiproton source and its principle of operation based on stochastic cooling.The subsequent six articles deal with the various physics subjects studied at the collider. Each article describes in detail the experimental results on a particular subject, and also provides the theoretical framework necessary for their interpretation. Finally the last two articles discuss the physics expectations from the improved collider (the so-called ACOL program, which has just started operation), and also from the next generation of ?supercolliders? which are being considered both in Europe and in the United States America.

Book Pion Kaon Proton and Antiproton Production in Proton Proton Collisions

Download or read book Pion Kaon Proton and Antiproton Production in Proton Proton Collisions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-22 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inclusive pion, kaon, proton, and antiproton production from proton-proton collisions is studied at a variety of proton energies. Various available parameterizations of Lorentz-invariant differential cross sections as a function of transverse momentum and rapidity are compared with experimental data. The Badhwar and Alper parameterizations are moderately satisfactory for charged pion production. The Badhwar parameterization provides the best fit for charged kaon production. For proton production, the Alper parameterization is best, and for antiproton production the Carey parameterization works best. However, no parameterization is able to fully account for all the data. Norbury, John W. and Blattnig, Steve R. Langley Research Center ANTIPROTONS; KAONS; PROTON ENERGY; SCATTERING CROSS SECTIONS; PIONS; PARAMETERIZATION; TRANSVERSE MOMENTUM

Book New Aspects of High Energy Proton Proton Collisions

Download or read book New Aspects of High Energy Proton Proton Collisions written by A. Ali and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Book Antiproton Nucleon and Antiproton Nucleus Interactions

Download or read book Antiproton Nucleon and Antiproton Nucleus Interactions written by F. Bradamante and published by Springer Science & Business Media. This book was released on 2013-03-12 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: The third course of the International School on Physics with Low Energy Antiprotons was held in Erice, Sicily at the Ettore Majorana Centre for Scientific Culture, from 10 to 18 June, 1988. The School is dedicated to physics accessible to experiments using low energy antiprotons, especially in view of operation of the LEAR facility at CERN with the upgraded antiproton source AAC (Antiproton Accumulator AA and Antiproton Collector ACOL). The first course in 1986 covered topics related to fundamental symmetries; the second course in 1987 focused on spectroscopy of light and heavy quarks. This book con tains the Proceedings of the third course, devoted to the experimental and theoretical aspects of the interaction of antinucleons with nucleons and nuclei. The Proceedings contain both the tutorial lectures and contributions presented by participants during the School. The papers are organized in several sections. The first section deals with the theoretical aspects of NN scattering and annihilation, and the underlying QCD. The experimental techniques and results concerning NN scattering are contained in Section II. Section III contains theoretical reviews and contributions on anti proton-nucleus scattering and bound states. Section IV is devoted to the experimental results on the antiproton nucleus systems and their phenomenological analysis. Finally, some possible developments of the antiproton machines are presented.

Book Physics in Collision 5

Download or read book Physics in Collision 5 written by B. Aubert and published by Atlantica Séguier Frontières. This book was released on 1986 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Search for New Heavy Charged Bosons and Measurement of High Mass Drell Yan Production in Proton Proton Collisions

Download or read book Search for New Heavy Charged Bosons and Measurement of High Mass Drell Yan Production in Proton Proton Collisions written by Markus Zinser and published by Springer. This book was released on 2018-09-25 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents two analyses, the first of which involves the search for a new heavy charged gauge boson, a so-called W' boson. This new gauge boson is predicted by some theories extending the Standard Model gauge group to solve some of its conceptual problems. Decays of the W' boson in final states with a lepton (l± = e± , μ±) and the corresponding (anti-)neutrino are considered. Data collected by the ATLAS experiment in 2015 at a center of mass energy of √s =13 TeV is used for the analysis. In turn, the second analysis presents a measurement of the double-differential cross section of the process pp->Z/gamma^* + X -> l^+l^- + X, including a gamma gamma induced contribution, at a center of mass energy of sqrt{s} = 8 TeV. The measurement is performed in an invariant mass region of 116 GeV to 1500 GeV as a function of invariant mass and absolute rapidity of the l^+l^-- pair, and as a function of invariant mass and pseudorapidity separation of the l^+l^-- pair. The data analyzed was recorded by the ATLAS experiment in 2012 and corresponds to an integrated luminosity of 20.3/fb. It is expected that the measured cross sections are sensitive to the PDFs at very high values of the Bjorken-x scaling variable, and to the photon structure of the proton.

Book Parameterized Cross Sections for Pion Production in Proton Proton Collisions

Download or read book Parameterized Cross Sections for Pion Production in Proton Proton Collisions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-03 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Book Physics in Collision 12

Download or read book Physics in Collision 12 written by John P. Cumalat and published by Atlantica Séguier Frontières. This book was released on 1993 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Spin Correlations in Tt Events from Pp Collisions

Download or read book Spin Correlations in Tt Events from Pp Collisions written by Boris Lemmer and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis introduces readers to the Standard Model, the top quark and its properties, before explaining the concept of spin correlation measurement. The first measurement of top quark spin correlations at the LHC in the lepton+jets decay channel is presented. As the heaviest elementary particle, the top quark plays an essential role in the Standard Model of elementary particle physics. In the case of top quarks being produced in pairs at hadron colliders, the Standard Model predicts their spins to be correlated. The degree of correlation depends on both the production mechanism and properties of the top quark. Any deviation from the Standard Model prediction can be an indicator for new physics phenomena. The thesis employs an advanced top quark reconstruction algorithm including dedicated identification of the up- and down-type quarks from the W boson decay.