Download or read book Search for Supersymmetric Particles in Final States with Multi leptons with the ATLAS Detector written by Huan Ren and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Measurement of WWW Production and Search for Supersymmetric Particles in Multi lepton Final States in Pp Collisions at square Root 8 written by Martina Javůrková and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The results presented in this thesis use the full dataset collected in 2012 by the ATLAS experiment from the LHC proton-proton collisions at sqrt(s) = 8 TeV, corresponding to an integrated luminosity of 20.3 fb^(−1). The first part is devoted to the search for the WWW production in the decay channel where each W boson decays leptonically (excluding leptonic tau decays). Upper limits are placed on the production cross-section in the fiducial phase space. The results are also interpreted in terms of the total cross-section when combined together with the semi-leptonic decay channel. In addition, limits on anomalous quartic gauge boson couplings in an effective field theory approach are extracted. The second part presents a search for supersymmetry in events with multiple jets, two leptons of identical charges or three leptons (electrons or muons). The absence of any excess in the signal regions with respect to the Standard Model expectations is interpreted in terms of limits in the parameter space of 14 supersymmetric models and one mUED model

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$^{-1}$.\\

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).

Download or read book Search for Supersymmetry in Final States with Leptons with the ATLAS Detector at the Large Hadron Collider written by and published by . This book was released on 2013 with total page 175 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...

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).

Download or read book Searches for Supersymmetry in Multilepton Final States with the ATLAS Detector written by Steven Farrell and published by . This book was released on 2014 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two searches for supersymmetry in multilepton final states are presented using pp collisions at sqrt(s) = 8 TeV in the ATLAS detector. First, a search for electroweak production of charginos and neutralinos in the three-lepton plus missing transverse momentum channel is detailed with an emphasis on the fake-lepton background estimation technique. No significant excess above the Standard Model prediction is observed in the signal regions. Exclusion limits are thus placed on simplified models of chargino1-neutralino2 production and decays via intermediate sleptons, SM gauge bosons, and Higgs bosons. The results are also interpreted in terms of the phenomenological MSSM. Next, a search for R-parity violating and R-parity conserving supersymmetric scenarios in the four-lepton channel is presented. No significant excess is observed, so exclusion limits are placed R-parity violating simplified models in which the lightest supersymmetric particle is the lightest neutralino, which promptly decays to leptons. Exclusion limits are also placed on R-parity conserving simplified models of neutralino2-neutralino3 production.

Download or read book Search for Strongly Interacting Supersymmetric Particles Decaying to Final States with an Isolated Lepton with the ATLAS Detector at the LHC written by Jeanette Lorenz and published by . This book was released on 2014 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Supersymmetry in Final States with Two Same Sign Leptons Or Three Leptons and Jets with the ATLAS Detector at the LHC written by Othmane Rifki and published by . This book was released on 2017 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Search for Supersymmetry in Final States with Three Leptons and Missing Transverse Energy with the ATLAS Detector at the Large Hadron Collider written by Itzebelt Santoyo Castillo and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pushing SUSY s Boundaries written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Electroweakly Produced Supersymmetric Particles in Final States Including Two Charged Leptons with the ATLAS Experiment at the LHC written by Josephine Wittkowski and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Search for Supersymmetry in Single lepton Final States with the ATLAS Detector and Improved Background Model for the Search of New Physics written by Stephan Horner and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zusammenfassung: Diese Dissertation präsentiert den Beitrag des Autors zur Suche nach supersymmetrischen Teilchen in Endzuständen mit genau einem hochenergetischen Lepton, verursacht durch Proton-Proton-Kollision am ATLAS-Experiment des Large Hadron Colliders. Darüberhinaus wird eine neue Methode zur Verbesserung der Untergrundmodelle in einer Suche nach neuer Physik vorgestellt

Download or read book A Search for Supersymmetry in Final States with Two Same flavor Opposite sign Leptons Jets and Missing Transverse Momentum with the ATLAS Detector written by Giulia Ripellino and published by . This book was released on 2017 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: