New Angular Search For Exotic Physics In The Photon Jet Final State Using The Atlas Detector On The Lhc PDF Download
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| Author | : Robert Keyes |
| Publisher | : |
| Total Pages | : |
| Release | : 2013 |
| Genre | : |
| ISBN | : |
Download New Angular Search for Exotic Physics in the Photon+jet Final State Using the ATLAS Detector on the LHC Book in PDF, ePub and Kindle
"This thesis outlines developments towards a new analysis and search technique for heavy resonances in angular distributions of photon+jet final states for the 2012 data set from the ATLAS detector on the LHC. In particular, a new angular variable tailored to the photon+jet channel was defined which distinguishes between background and expected signals, the corresponding angular observable sensitivity was optimized using ATLAS excited quark samples and JetPhox MC samples, and an optimal mass binning scheme was derived from the measured mass resolution. Ongoing work is being done to publish the analysis." --
| Author | : Valerio Rossetti |
| Publisher | : Springer |
| Total Pages | : 173 |
| Release | : 2015-08-24 |
| Genre | : Science |
| ISBN | : 3319222252 |
Download Search for Exotic Mono-jet Events Book in PDF, ePub and Kindle
This thesis describes in detail the search for new phenomena in mono-jet final states with the ATLAS experiment at the LHC. The final state is considered the golden channel in the searches for large extra dimensions (LED) but also allows access to a very rich SUSY-related phenomenology pertaining to the production of weakly interacting massive particles (WIMPS), SUSY Dark Matter candidates, GMSB SUSY models with very light gravitino masses, as well as stop an sbottom pair production in compressed scenarios (with nearly degenerated squarks and the lightest neutralino), and also invisible Higgs searches, among others. Here, a number of these scenarios are explored. The measurements presented yield new powerful constraints on the existence of extra spatial dimensions, the pair production of WIMPs, and also provide the best limit to date on the gravitino mass.
| Author | : Sheir Yarkoni |
| Publisher | : |
| Total Pages | : |
| Release | : 2015 |
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Download New Physics Searches in Angular Shapes of Photon+jet Events in 2013 ATLAS Data Book in PDF, ePub and Kindle
"The Large Hadron Collider at CERN, Switzerland, was built to both refine current Standard Model measurements, as well as discover new physics beyond the Standard Model. Using data from the general-purpose ATLAS detector, we take a step towards answering one of these questions: are quarks point-like, or do they themselves have sub-structure? By investigating the angular correlations in photon+jet events we address this question. The final goal of this thesis was to produce a feasible method to test deviations from the Standard Model using 2012 ATLAS data. A new data-driven background estimation analysis technique was developed to test for significant deviations from Standard Model predictions. We parametrize the angular separation between the leading photon and jet in each event with the variable $\psi = \log(\exp([pipe]\eta_\gamma-\eta_j[pipe])+1)$ (where $\eta$ is pseudorapidity) using standard ATLAS Monte Carlo generators Pythia, Sherpa, and JetPhox. Kinematic comparisons are performed between 2012 ATLAS data and Monte Carlo samples to show how well data is described by the generators. We take the ratio of the number of narrowly-separated ($\psi
| Author | : Giuliano Gustavino |
| Publisher | : Springer |
| Total Pages | : 245 |
| Release | : 2017-06-19 |
| Genre | : Science |
| ISBN | : 3319588710 |
Download Search for New Physics in Mono-jet Final States in pp Collisions Book in PDF, ePub and Kindle
This thesis provides a detailed and comprehensive description of the search for New Physics at the Large Hadron Collider (LHC) in the mono-jet final state, using the first 3.2 fb-1 of data collected at the centre of mass energy of colliding protons of 13~TeV recorded in the ATLAS experiment at LHC. The results are interpreted as limits in different theoretical contexts such as compressed supersymmetric models, theories that foresee extra-spatial dimensions and in the dark matter scenario. In the latter the limits are then compared with those obtained by other ATLAS analyses and by experiments based on completely different experimental techniques, highlighting the role of the mono-jet results in the context of dark matter searches.Lastly, a set of possible analysis improvements are proposed to reduce the main uncertainties that affect the signal region and to increase the discovery potential by further exploiting the information on the final state.
| Author | : Lene Kristian Bryngemark |
| Publisher | : Springer |
| Total Pages | : 177 |
| Release | : 2017-12-29 |
| Genre | : Science |
| ISBN | : 3319673467 |
Download Search for New Phenomena in Dijet Angular Distributions at √s = 8 and 13 TeV Book in PDF, ePub and Kindle
This thesis describes the use of the angular distributions of the most energetic dijets in data recorded by the ATLAS experiment, at CERN’s Large Hadron Collider (LHC), the goal of which is to search for phenomena beyond what the current theory of Particle Physics (the Standard Model) can describe. It also describes the deployment of the method used in ATLAS to correct for the distortions in jet energy measurements caused by additional proton–proton interactions. The thesis provides a detailed introduction to understanding jets and dijet searches at the LHC. The experiments were carried out at two record collider centre-of-mass energies (8 and 13 TeV), probing smaller distances than ever before. Across a broad momentum transfer range, the proton constituents (quarks and gluons) display the same kinematical behaviour, and thus still appear to be point-like. Data are compared to predictions corrected for next-to-leading order quantum chromodynamics (NLO QCD) as well as electroweak effects, demonstrating excellent agreement. The results are subsequently used to set limits on parameters of suggested theoretical extensions to the Standard Model (SM), including the effective coupling and mass of a Dark Matter mediator.
| Author | : Aviv Ruben Cukierman |
| Publisher | : |
| Total Pages | : |
| Release | : 2020 |
| Genre | : |
| ISBN | : |
Download Searches for New Physics Using Jets with the ATLAS Detector Book in PDF, ePub and Kindle
The Large Hadron Collider produces particle collisions at the highest energies ever observed in a scientific experiment. This apparatus is built to test the predictions of the Standard Model of Particle Physics, including the existence and properties of the Higgs boson. As a proton-proton collider, quarks and gluons are produced in abundance, which quickly fragment and hadronize into collimated showers of energy called jets. These jets are detected and measured in the ATLAS detector, which is built around the point of the proton-proton collisions to observe the products of these interactions. Three major original research efforts are presented using data from proton-proton collisions observed in ATLAS. The first analyzes events with jets and photons to search for a beyond-the-Standard-Model decay of the Higgs boson. The second utilizes novel techniques in weak supervision to perform a generic data-driven resonance search in events with two jets. The third formalizes the calibration of the jet energies observed in the ATLAS detector, and further proposes a new method to improve this calibration with machine learning. The work presented here addresses some of the key questions in particle physics today. By searching for new physics, it is possible to shed light on the nature of the Higgs boson and the possibility of physics beyond the Standard Model. These searches focus on processes involving multiple jets in the final state, which motivates innovations in the reconstruction of jet energies. In addition to setting new bounds on theoretically interesting models, the innovations in object reconstruction and analysis techniques developed in this work can be applied in other ATLAS efforts using currently available data or data gathered in the future.
| Author | : Chiara Rizzi |
| Publisher | : Springer Nature |
| Total Pages | : 279 |
| Release | : 2020-09-01 |
| Genre | : Science |
| ISBN | : 3030528774 |
Download Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector Book in PDF, ePub and Kindle
This PhD thesis documents two of the highest-profile searches for supersymmetry performed at the ATLAS experiment using up to 80/fb of proton-proton collision data at a center-of-mass energy of 13 TeV delivered by the Large Hadron Collider (LHC) during its Run 2 (2015-2018). The signals of interest feature a high multiplicity of jets originating from the hadronisation of b-quarks and large missing transverse momentum, which constitutes one of the most promising final state signatures for discovery of new phenomena at the LHC. The first search is focused on the strong production of a pair of gluinos, with each gluino decaying into a neutralino and a top-antitop-quark pair or a bottom-antibottom-quark pair. The second search targets the pair production of higgsinos, with each higgsino decaying into a gravitino and a Higgs boson, which in turn is required to decay into a bottom-antibottom-quark pair. Both searches employ state-of-the-art experimental techniques and analysis strategies at the LHC, resulting in some of the most restrictive bounds available to date on the masses of the gluino,neutralino, and higgsino in the context of the models explored.
| Author | : |
| Publisher | : |
| Total Pages | : 155 |
| Release | : 2012 |
| Genre | : |
| ISBN | : |
Download Search for New Physics in Diphoton and ETmiss Final States Using the ATLAS Detector at the LHC Book in PDF, ePub and Kindle
| Author | : Elodie Resseguie |
| Publisher | : Springer Nature |
| Total Pages | : 336 |
| Release | : 2020-11-03 |
| Genre | : Science |
| ISBN | : 3030570169 |
Download Electroweak Physics at the Large Hadron Collider with the ATLAS Detector Book in PDF, ePub and Kindle
This thesis discusses searches for electroweakly produced supersymmetric partners of the gauge and the Higgs bosons (gauginos and higgsinos) decaying to multiple leptons, using pp collisions at sqrt(s) = 13 TeV. The thesis presents an in-depth study of multiple searches, as well as the first 13 TeV cross section measurement for the dominant background in these searches, WZ production. Two searches were performed using 36.1/fb of data: the gaugino search, which makes use of a novel kinematic variable, and the higgsino search, which produced the first higgsino limits at the LHC. A search using 139/fb of data makes use of a new technique developed in this thesis to cross check an excess of data above the background expectation in a search using a Recursive Jigsaw Reconstruction technique. None of the searches showed a significant excess of data, and limits were expanded with respect to previous results. These searches will benefit from the addition of luminosity during HL-LHC; however, the current detector will not be able to withstand the increase in radiation. Electronics for the detector upgrade are tested and irradiated to ensure their performance.
| Author | : Maximilian Swiatlowski |
| Publisher | : |
| Total Pages | : |
| Release | : 2015 |
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| ISBN | : |
Download Measuring the Standard Model and Searching for New Physics with Jet Substructure Using the ATLAS Detector Book in PDF, ePub and Kindle
Collisions at the Large Hadron Collider have offered an unprecedented window into some of the highest energy scales ever observed in experiments. Understanding these collisions, especially those that produce particles charged under quantum chromodynamics (QCD), requires a deep understanding of jets: the collimated sprays of particles produced by the parton shower and hadronization processes which emerge from the asymptotic freedom of QCD. Recent theoretical advances and the unprecedented capabilities of the ATLAS detector have enabled a new class of jet physics measurements based on the internal structure of jets, referred to as jet substructure. Three new types of measurements relying on jet substructure are presented. The first is a set of measurements sensitive which can discriminate between jets initiated by quarks and gluons. Separation is possible by studying variables sensitive to the magnitude of the color charge. Several such variables are measured, and a data-driven technique is used to construct a tagger, the first of its kind at a hadron collider, which can improve the sensitivity of searches for new physics in hadronic final states. A second measurement studies the color connections of jets in top-antitop events using an observable called the jet pull angle: sensitivity to the color representation of particles decaying to dijet pairs at a hadron collider is demonstrated for the first time. A final analysis searches for R-parity violating supersymmetry (SUSY) in all hadronic final states. These classes of models remove the characteristic missing energy signature which existing SUSY searches rely on, and require new discrimination techniques. Jet substructure provides a powerful handle to analyze these very high multiplicity states using a variable called the total jet mass. No signal is observed over the Standard Model (SM) prediction, and new limits are set on these previously unexplored models. The techniques of jet substructure lie at the hearts of all of these analyses, enabling both new measurements of SM phenomena and entirely new searches for physics beyond the SM.
