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Supersymmetry Searches In Events With At Least Four Leptons Using The Atlas Detector At The Large Hadron Collider
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Book Synopsis Supersymmetry Searches in Events with at Least Four Leptons Using the ATLAS Detector at the Large Hadron Collider by : Zara Grout
Download or read book Supersymmetry Searches in Events with at Least Four Leptons Using the ATLAS Detector at the Large Hadron Collider written by Zara Grout and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Third generation SUSY and t ̄t +Z production by : Josh McFayden
Download or read book Third generation SUSY and t ̄t +Z production written by Josh McFayden and published by Springer. This book was released on 2014-06-06 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes searches for new particles predicted by the super symmetry (SUSY) theory, a theory extending beyond the current Standard Model of particle physics, using the ATLAS detector at the CERN Large Hadron Collider. The thesis focuses on searches for stop and sbottom squarks, the SUSY partners of the top and bottom quarks, which are expected to be lighter than the partners of the first and second generation quarks and therefore good candidates for the first evidence of SUSY. It describes novel techniques for estimating and rejecting the Standard-Model backgrounds to searches for these particles. It also includes an independent analysis seeking to constrain the Standard Model ttZ background process, which also represents the first ATLAS search for this rare process at the LHC. The stop squark analysis described, with substantial leading contributions from the author, is the first search for these particles at the LHC to use the jets plus missing transverse energy plus 0-lepton signature and provides the world's best limits on the stop mass for light neutralino LSPs. All in all, the thesis describes three different world-leading analyses in both Standard Model and SUSY physics and therefore represents a major contribution to the field.
Book Synopsis A Search for Displaced Leptons in the ATLAS Detector by : Lesya Horyn
Download or read book A Search for Displaced Leptons in the ATLAS Detector written by Lesya Horyn and published by Springer Nature. This book was released on 2022-02-07 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters. This signature provides unique sensitivity to the production of theoretical lepton-partners, sleptons. These particles are a feature of supersymmetric theories, which seek to address unanswered questions in nature. The signature searched for in this thesis is difficult to identify, and in fact, this is the first time it has been probed at the Large Hadron Collider (LHC). It covers a long-standing gap in coverage of possible new physics signatures. This thesis describes the special reconstruction and identification algorithms used to select leptons with large impact parameters and the details of the background estimation. The results are consistent with background, so limits on slepton masses and lifetimes in this model are calculated at 95% CL, drastically improving on the previous best limits from the Large Electron Positron Collider (LEP).
Book Synopsis Electroweak Physics at the Large Hadron Collider with the ATLAS Detector by : Elodie Resseguie
Download or read book Electroweak Physics at the Large Hadron Collider with the ATLAS Detector written by Elodie Resseguie and published by Springer Nature. This book was released on 2020-11-03 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for Supersymmetry in Final States with Leptons with the ATLAS Detector at the Large Hadron Collider by : Matthias Hamer
Download or read book Search for Supersymmetry in Final States with Leptons with the ATLAS Detector at the Large Hadron Collider written by Matthias Hamer and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: After a short review of the Standard Model of Elementary Particle Physics and its minimal supersymmetric extension, the MSSM, a global analysis of two highly simplified supersymmetric models, the CMSSM and the NUHM1 is presented, with a focus on the fine-tuning of these models. A new, phenomenologically motivated measure for fine-tuning is introduced. In addition, a search for supersymmetry in final states with four leptons is presented, where a procedure for the consideration of trigger efficiencies with a focus on the calculation of uncertainties on the sum of event weights is given. Fina ...
Book Synopsis Search for Scalar Top Quarks and Higgsino-Like Neutralinos by : Takuya Nobe
Download or read book Search for Scalar Top Quarks and Higgsino-Like Neutralinos written by Takuya Nobe and published by Springer. This book was released on 2015-11-30 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports a search for theoretically natural supersymmetry (SUSY) at the Large Hadron Collider (LHC). The data collected with the ATLAS detector in 2012 corresponding to 20 /fb of an integrated luminosity have been analyzed for stop pair production in proton–proton collisions at a center-of-mass energy of 8 TeV at the Large Hadron Collider (LHC) in the scenario of the higgsino-like neutralino. The author focuses on stop decaying into a bottom quark and chargino. In the scenario of the higgsino-like neutralino, the mass difference between charginos and neutralinos (Δm) is expected to be small, and observable final-state particles are likely to have low-momentum (soft). The author develops a dedicated analysis with a soft lepton as a probe of particles from chargino decay, which suppresses the large amount of backgrounds. As a result of the analysis, no significant SUSY signal is observed. The 95% confidence-level exclusion limits are set to masses of stop and neutralino assuming Δm = 20 GeV. The region with ΔM (the mass difference between stop and neutralino) 70 GeV is excluded for the first time at stop mass of less than 210 GeV. The author also excludes the signals with ΔM 120 GeV up to 600 GeV of stop mass with neutralino mass of less than 280 GeV. The author clearly shows very few remaining parameter spaces for light stop (e.g., topology of stop decay is extremely similar to the SM top quark) by combining his results and previous ATLAS analyses. His results provide a strong constraint to searches for new physics in the future.
Book Synopsis Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector by : Chiara Rizzi
Download or read book Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector written by Chiara Rizzi and published by Springer Nature. This book was released on 2020-09-01 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis High Jet Multiplicity Physics at the LHC by : Mireia Crispín Ortuzar
Download or read book High Jet Multiplicity Physics at the LHC written by Mireia Crispín Ortuzar and published by Springer. This book was released on 2016-08-25 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes research in two different areas of state-of-the-art hadron collider physics, both of which are of central importance in the field of particle physics. The first part of the book focuses on the search for supersymmetric particles called gluinos. The book subsequently presents a set of precision measurements of “multi-jet” collision events, which involve large numbers of newly created particles, and are among the dominant processes at the Large Hadron Collider (LHC). Now that a Higgs boson has been discovered at the LHC, the existence (or non-existence) of supersymmetric particles is of the utmost interest and significance, both theoretically and experimentally. In addition, multi-jet collision events are an important background process for a wide range of analyses, including searches for supersymmetry.
Book Synopsis Physics with Photons Using the ATLAS Run 2 Data by : Stefano Manzoni
Download or read book Physics with Photons Using the ATLAS Run 2 Data written by Stefano Manzoni and published by Springer. This book was released on 2019-08-02 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for New Physics in Mono-jet Final States in pp Collisions by : Giuliano Gustavino
Download or read book Search for New Physics in Mono-jet Final States in pp Collisions written by Giuliano Gustavino and published by Springer. This book was released on 2017-06-19 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for Supersymmetry in Events with Leptons (e, Μ, Τ), Jets and Missing Transverse Energy with the ATLAS Detector at the LHC. by : Anthony Rose
Download or read book Search for Supersymmetry in Events with Leptons (e, Μ, Τ), Jets and Missing Transverse Energy with the ATLAS Detector at the LHC. written by Anthony Rose and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Third Generation Susy and T-T +Z Production by : Josh McFayden
Download or read book Third Generation Susy and T-T +Z Production written by Josh McFayden and published by . This book was released on 2014-06-30 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Searches for Electroweak Production of Compressed Supersymmetry in Events with Soft Leptons, Missing Transverse Momentum, and a Hard Jet in the Atlas Detector by : Sheena Calie Schier
Download or read book Searches for Electroweak Production of Compressed Supersymmetry in Events with Soft Leptons, Missing Transverse Momentum, and a Hard Jet in the Atlas Detector written by Sheena Calie Schier and published by . This book was released on 2018 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supersymmetry (SUSY) is an extension of the Standard Model that predicts a boson (fermion) partner for each fermion (boson) in the Standard Model. Weak-scale SUSY is attractive for reasons like improving gauge coupling unification, reducing fine-tuning in the Higgs sector and providing a dark matter candidate. This thesis presents a dedicated search for direct production of new, colorless, weak-scale states with compressed mass spectra in final states characterized by soft visible decay products. This analysis uses pp collisions at [Special character omitted] = 13 TeV at the Large Hadron Collider and collected by the ATLAS experiment during 2015 and 2016 corresponding to 36.1 fb --1 of integrated luminosity. This analysis selects events with two soft electrons or muons, an intermediate amount of missing transverse momentum (Emiss), and a hard jet. Backgrounds with two prompt T leptons are estimated with Monte Carlo simulation, while reducible backgrounds are estimated with a mix of Monte Carlo and data-driven methods. Results are consistent with Standard Model expectations and used to put limits on compressed supersymmetric states. Limits are extended on compressed electroweak SUSY model for the first time since the Large Electron Positron Collider (LEP).
Book Synopsis Search for Supersymmetric Particles in Final States with Leptons, Jets and Missing Transverse Energy with the ATLAS Detector by : Peter Tornambè
Download or read book Search for Supersymmetric Particles in Final States with Leptons, Jets and Missing Transverse Energy with the ATLAS Detector written by Peter Tornambè and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Supersymmetry (SUSY) is one of the most studied models to extend the Standard Model (SM) of Particle Physics beyond the electroweak scale. In many supersymmetric models, the lightest supersymmetric particle is stable and can be a suitable candidate for dark matter.\\ This dissertation summarises a search for supersymmetric phenomena produced via the strong or the electroweak interaction leading to final states with two leptons (electrons or muons) of the same electric charge, or three leptons, jets and missing transverse momentum. While the same-sign or three leptons signature is present in many SUSY scenarios, SM processes leading to such events have very small production rates. Therefore, this analysis benefits from a small SM background in the signal regions leading to a good sensitivity especially in SUSY scenarios with compressed mass spectra or in which the R-parity is not conserved. The search was performed with cut-and-count analyses exploiting the full dataset recorded with the ATLAS detector at the Large Hadron Collider during the years 2015 and 2016, corresponding to a total integrated luminosity of 36.1 fb$^{-1}$. No significant excess above the Standard Model expectations is observed. The results are interpreted in several simplified supersymmetric models featuring R-parity conservation or R-parity violation, extending the exclusion limits from previous searches.\\ Since no sign of SUSY particles has been observed, this dissertation presents prospects for a search for compressed electroweakino production. This supersymmetric scenario is particularly challenging for LHC experiments since the products of the decay chain have low energies and are therefore difficult to detect. Results are obtained with a parameterised simulation of the ATLAS detector performances at a centre-of-mass energy of 14 TeV and for an integrated luminosity of 3000 fb$^{-1}$.\\
Book Synopsis Search for Exotic Mono-jet Events by : Valerio Rossetti
Download or read book Search for Exotic Mono-jet Events written by Valerio Rossetti and published by Springer. This book was released on 2015-08-24 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Searches for Dijet Resonances by : Lydia Audrey Beresford
Download or read book Searches for Dijet Resonances written by Lydia Audrey Beresford and published by Springer. This book was released on 2018-09-04 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Supersymmetric Beasts and Where to Find Them by : Marco Valente
Download or read book Supersymmetric Beasts and Where to Find Them written by Marco Valente and published by Springer Nature. This book was released on 2022-03-05 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: After an extensive overview of the Standard Model and of the theory and phenomenology of Supersymmetry, this book describes the recent development of the ATLAS Particle Flow algorithm, a hadronic reconstruction technique aiming at enhancing the sensitivity of the experiment to new physics through the combination of the information from different ATLAS sub-detectors. The first ever ATLAS strong SUSY search exploiting this technique is also described, reporting the results and exclusion limits obtained using the complete proton-proton collision dataset recorded by the ATLAS experiment during the second Run of the Large Hadron Collider (LHC).
