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.

Download or read book Inclusive b Jet Production in Proton Proton Collisions written by Patrick L.S. Connor and published by Springer Nature. This book was released on 2019-11-29 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: ^ 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.

Download or read book Parameterized Cross Sections for Pion Production in Proton Proton Collisions written by Steve R. Blattnig and published by . This book was released on 2000 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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

Download or read book Inclusive b Jet Production in Proton Proton Collisions written by Patrick L.S. Connor and published by Springer. This book was released on 2019-12-11 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: ^ 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.

Download or read book Inclusive B Jet Production in Proton Proton Collisions written by Patrick L.S. Connor and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

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:

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.

Download or read book A Measurement of the T T bar Production Cross Section in Proton antiproton Collisions at Sqrt s written by Markus Klute and published by . This book was released on 2004 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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

Download or read book Total Cross Section Measurements written by G. Giacomelli and published by Elsevier. This book was released on 2013-10-22 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Total Cross-Section Measurements discusses the cross-sectional dimensions of elementary hadron collisions. The main coverage of the book is the resonance and high energy area of the given collision. A section of the book explains in detail the characteristic of a resonance region. Another section is focused on the location of the high energy region of collision. Parts of the book define the meaning of resonance in nuclear physics. Also explained are the measurement of resonance and the identification of the area where the resonance originates. Different experimental methods to measure the total cross section of a charged particle are given. One such method is the transmission method. Bubble chamber measurement is another method that is covered in the book. Systems of analysis such as the pion-nucleon system, the K–-nucleon system, and K+- nucleon system are discussed. The book is an excellent guide for nuclear physicists and students of physics.

Download or read book Deep Inelastic Positron Proton Scattering in the High Momentum Transfer Regime of HERA written by Ulrich F. Katz and published by Springer. This book was released on 2003-07-01 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: About three decades after the first experiments on deep inelastic lepton hadron scattering began to investigate the structure of hadrons, the history of this fruitful field of particle physics continues in the broad spectrum of research performed at the electron and positron proton collider HERA at DESY, where the multipurpose detectors ZEUS and H1 access ep scattering at a center of mass energy of 300 GeV and explore as yet uncharted kinematic realms of deep inelastic scattering. After the first years of data taking at HERA, each of the experiments has collected a total of roughly 40 pb 1 of e+p data, yielding sensitivity to deep inelastic e+p interactions at high four momentum transfers, Q2, where typi cal cross sections drop into the subpicobarn regime. This kinematic domain is characterized by electroweak unification, manifesting itself most markedly in the neutral and charged current cross sections, which approach an equal order of magnitude as Q2 rises above the square of the W and Z masses. Consequently, HERA allows, for the first time, studies of both types of pro cesses simultaneously with the same initial state conditions and in the same detector, and thus we can investigate the interplay of electroweak and strong forces governing the respective cross sections.

Download or read book Study of Double Parton Scattering in Photon 3 Jets Final State written by You-Hao Chang and published by Springer. This book was released on 2017-01-20 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book mainly focuses on the study of photon + 3 jets final state in Proton-Proton Collisions at √s = 7TeV, searching for patterns of two (or more) distinct hard scatterings in the same collision, i.e the so-called Double Parton Scattering (DPS). A new method by using Monte Carlo generators was performed and provides higher order corrections to the description of the Single Parton Scattering (SPS) background. Further it is investigated whether additional contributions from DPS can improve the agreement between the measured data and the Monte Carlo predictions. The current theoretical uncertainties related to the SPS background are found to be larger than expectation. At the same time a rich set of DPS-sensitive measurements is reported for possible further interpretation.

Download or read book High Transverse Momentum Direct Photon Production at Fermilab Fixed target Energies written by Leonard Apanasevich and published by . This book was released on 2005 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 . This book was released on 2018 with total page 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 WØ 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 WØ boson in final states with a lepton (l± = e±, æ±) and the corresponding (anti- )neutrino are considered. Data collected by the ATLAS experiment in 2015 at a center of mass energy of sqrt{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.

Download or read book Dijet Angular Distributions in Proton Proton Collisions written by Nele Boelaert and published by Springer Science & Business Media. This book was released on 2011-10-26 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is based on the first data from the Large Hadron Collider (LHC) at CERN. Its theme can be described as the classical Rutherford scattering experiment adapted to the LHC: measurement of scattering angles to search for new physics and substructure. At the LHC, colliding quarks and gluons exit the proton collisions as collimated particle showers, or jets. The thesis presents studies of the scattering angles of these jets. It includes a phenomenological study at the LHC design energy of 14 TeV, where a model of so-called large extra dimensions is used as a benchmark process for the sensitivity to new physics. The experimental result is the first measurement, made in 2010, by ATLAS, operating at the LHC start-up energy of 7 TeV. The result is compatible with the Standard Model and demonstrates how well the physics and the apparatus are understood. The first data is a tiny fraction of what will be accumulated in the coming years, and this study has set the stage for performing these measurements with confidence as the LHC accumulates luminosity and increases its energy, thereby probing smaller length scales.

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.