Jet Calibration Cross Section Measurements And New Physics Searches With The Atlas Experiment Within The Run 2 Data PDF Download
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| Author | : Robert Hankache |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2019 |
| Genre | : |
| ISBN | : |
Download Jet Calibration, Cross Section Measurements and New Physics Searches with the ATLAS Experiment Within the Run 2 Data Book in PDF, ePub and Kindle
The Standard Model is the current theory used to describe the elementary particles and their fundamental interactions (except the gravity). My PhD within the ATLAS experiment put this model under test using objects called jets, to study final state particles that interact through the strong force. First, I contributed to a method of jet calibration aiming at calibrating the energy scale of jets in the forward region of the detector with respect to central region. I improved the calibration by making it faster and more precise. Next, I worked on a search analysis of new physics using events with two jets. The Standard Model predicts a smooth distribution of the invariant mass of di-jets, hence we search for a bump which could come from a new particle. Since no significant bump is found, we put limits on signals as predicted by Beyond Standard Model theories and on model-independent signals. Last, I developed a new physics analysis measuring the leading (highest in transverse momentum) jet differential cross-section as a function of transverse momentum and rapidity. The challenge was to factorize the detector effects (resolution and acceptance) from the observable, which I did using a new unfolding technique. I also worked on the theoretical predictions calculation which was very challenging to perform and needed the implementation of special regularizations. The measurement and the predictions are then compared and tensions are observed due to the difficulties of theoretical predictions calculation.
| Author | : Stefano Manzoni |
| Publisher | : Springer |
| Total Pages | : 265 |
| Release | : 2019-08-02 |
| Genre | : Science |
| ISBN | : 3030243702 |
Download Physics with Photons Using the ATLAS Run 2 Data Book in PDF, ePub and Kindle
The work presented in this book is based on the proton-proton collision data from the Large Hadron Collider at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector in 2015 and 2016. The research program of the ATLAS experiment includes the precise measurement of the parameters of the Standard Model, and the search for signals of physics beyond the SM. Both these approaches are pursued in this thesis, which presents two different analyses: the measurement of the Higgs boson mass in the di-photon decay channel, and the search for production of supersymmetric particles (gluinos, squarks or winos) in a final state containing two photons and missing transverse momentum. Finally, ATLAS detector performance studies, which are key ingredients for the two analyses outlined before, are also carried out and described.
| Author | : Jan Kieseler |
| Publisher | : Springer |
| Total Pages | : 172 |
| Release | : 2016-06-15 |
| Genre | : Science |
| ISBN | : 3319400053 |
Download Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass Book in PDF, ePub and Kindle
This thesis presents the first experimental calibration of the top-quark Monte-Carlo mass. It also provides the top-quark mass-independent and most precise top-quark pair production cross-section measurement to date. The most precise measurements of the top-quark mass obtain the top-quark mass parameter (Monte-Carlo mass) used in simulations, which are partially based on heuristic models. Its interpretation in terms of mass parameters used in theoretical calculations, e.g. a running or a pole mass, has been a long-standing open problem with far-reaching implications beyond particle physics, even affecting conclusions on the stability of the vacuum state of our universe. In this thesis, this problem is solved experimentally in three steps using data obtained with the compact muon solenoid (CMS) detector. The most precise top-quark pair production cross-section measurements to date are performed. The Monte-Carlo mass is determined and a new method for extracting the top-quark mass from theoretical calculations is presented. Lastly, the top-quark production cross-sections are obtained – for the first time – without residual dependence on the top-quark mass, are interpreted using theoretical calculations to determine the top-quark running- and pole mass with unprecedented precision, and are fully consistently compared with the simultaneously obtained top-quark Monte-Carlo mass.
| Author | : Moritz Backes |
| Publisher | : Springer |
| Total Pages | : 268 |
| Release | : 2014-06-11 |
| Genre | : Science |
| ISBN | : 331907136X |
Download Measurement of the Inclusive Electron Cross-Section from Heavy-Flavour Decays and Search for Compressed Supersymmetric Scenarios with the ATLAS Experiment Book in PDF, ePub and Kindle
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
| Author | : Rodger Mantifel |
| Publisher | : |
| Total Pages | : |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
Download Measurement of the Production Cross Section of Jets in Association with a Z Boson in 8 TeV Proton-proton Collisions with the ATLAS Detector Book in PDF, ePub and Kindle
"This thesis presents the measurement of the production cross sections of jets in association with a Z boson in proton-proton collisions at √s = 8 TeV with an integrated luminosity of 20.3 fb−1 recorded by the ATLAS experiment at the Large Hadron Collider at CERN. Inclusive and differential Z/[gamma]∗(→ e+e−)+jets cross sections are measured for jets with a transversemomentum pT(jet) > 30 GeV and rapidity |y(jet)| 4.4. Z boson candidates are identified by their decay into electron pairs. In order to stringently probe the modelling of Z/[gamma]∗+jets production by Monte Carlo generators in regions of high-pT phase space typical for Higgs boson decay and searches for new physics, events with high-pT final states are investigated. High-pT final states are defined as events with either pT(Z) 300 GeV or pT(leading jet) > 300 GeV. A set of four observables, sensitive to the topology of the event, are measured for the standard event selection as well as in the regions of high-pT phase space. The results from data are unfolded to particle level and compared to calculations of the matrix element from Monte Carlo generators Alpgen+Pythia and Sherpa interfaced to a parton shower. The results show that Sherpa tends to model Z/[gamma]∗+jets production in high-pT regions of phase space much better than Alpgen+Pythia." --
| Author | : |
| Publisher | : |
| Total Pages | : 748 |
| Release | : 2009 |
| Genre | : Beauty particles |
| ISBN | : |
Download Expected Performance of the ATLAS Experiment Book in PDF, ePub and Kindle
| Author | : Markus Zinser |
| Publisher | : Springer |
| Total Pages | : 386 |
| Release | : 2018-09-25 |
| Genre | : Science |
| ISBN | : 3030006506 |
Download Search for New Heavy Charged Bosons and Measurement of High-Mass Drell-Yan Production in Proton—Proton Collisions Book in PDF, ePub and Kindle
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.
| Author | : Lydia Audrey Beresford |
| Publisher | : Springer |
| Total Pages | : 175 |
| Release | : 2018-09-04 |
| Genre | : Science |
| ISBN | : 331997520X |
Download Searches for Dijet Resonances Book in PDF, ePub and Kindle
This book addresses one of the most intriguing mysteries of our universe: the nature of dark matter. The results presented here mark a significant and substantial contribution to the search for new physics, in particular for new particles that couple to dark matter. The first analysis presented is a search for heavy new particles that decay into pairs of hadronic jets (dijets). This pioneering analysis explores unprecedented dijet invariant masses, reaching nearly 7 TeV, and sets constraints on several important new physics models. The two subsequent analyses focus on the difficult low dijet mass region, down to 200 GeV, and employ a novel technique to efficiently gather low-mass dijet events. The results of these analyses transcend the long-standing constraints on dark matter mediator particles set by several existing experiments.
| Author | : Arno Straessner |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 221 |
| Release | : 2010-03-31 |
| Genre | : Science |
| ISBN | : 3642051685 |
Download Electroweak Physics at LEP and LHC Book in PDF, ePub and Kindle
During more than 10 years, from 1989 until 2000, the LEP accelerator and the four LEP experiments, ALEPH, DELPHI, L3 and OPAL, have taken data for a large amount of measurements at the frontier of particle physics. The main outcome is a thorough and successful test of the Standard Model of electroweak interactions. Mass and width of the Z and W bosons were measured precisely, as well as the Z and photon couplings to fermions and the couplings among gauge bosons. The rst part of this work will describe the most important physics results of the LEP experiments. Emphasis is put on the properties of the W boson, which was my main research eld at LEP. Especially the precise determination of its mass and its couplings to the other gauge bosons will be described. Details on physics effects like Colour Reconnection and Bose-Einstein Correlations in W-pair events shall be discussed as well. A conclusive summary of the current electroweak measurements, including low-energy results, as the pillars of possible future ndings will be given. The important contributions from Tevatron, like the measurement of the top quark and W mass, will round up the present day picture of electroweak particle physics.
| Author | : Daniel Robert Clements |
| Publisher | : |
| Total Pages | : |
| Release | : 2008 |
| Genre | : |
| ISBN | : |
Download Jet Physics at ATLAS. Book in PDF, ePub and Kindle
The use and optimisation of integration grid techniques to generate next-to-leading order predictions of jet cross-sections, independent of parton distribution functions, was investigated. Such methods were found to provide an accurate approximation to a standard Monte-Carlo simulation (within 1%) and enable collider data to be readily included in global PDF fitting procedures. However, the benefit of including inclusive-jet cross-section data from ATLAS in global fits is only significant if the jet energy scale (JES) can be constrained to ~1% at high pT. Uncertainties in the theoretical prediction of the inclusive-jet cross-section such as PDFs and fixed-order (scale) uncertainties were studied and compared with experimental errors arising from jet energy resolution and absolute scale. These uncertainties were then considered in the context of a quark compositeness search where a sensitivity to a compositeness scale of Lambda10TeV can be achieved with 10 inverse femtobarns of data, if the jet energy scale can be constrained to ~1%. An analysis using dijet angular distributions found a similar sensitivity without the dependence on the jet energy scale. A potential method of evaluating the stability of the jet energy scale out to high pT by Hbootstrapping the calibration at low pT by the use of multi-jet events was also investigated. This suggests that a calorimeter non-linearity can be detected for jets with pT500GeV at ~1.5%/500GeV (i.e. a 1.5% change in JES over 500GeV in pT). An investigation of inner-detector commissioning issues associated with the ATLAS Semiconductor Tracker (SCT), including a review of Hnoisy modules on the SCT Barrel (from May 2007) was carried out. In addition a tool for DCS monitoring within the online monitoring framework was developed and tested during the M5 and M6 commissioning weeks. Finally, a method of assessing the track reconstruction efficiency by track-insertion was considered for the particular case of minimum bias events.
