Download or read book Searching for Supersymmetry with Tri Leptons and Missing Transverse Energy Using the CMS Experiment at the Large Hadron Collider written by Nikoloz Skhirtladze and published by . This book was released on 2013 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we target supersymmetry scenarios where the colored superpartners are assumed to be heavy (and decoupled). We consider the possibility of light sleptons, giving rise to pp ..., where the decays to leptons are mediated by intermediate on-shell sleptons. We also consider the possibility that the sleptons are heavy, leaving only three-body decays through Standard Model W's and Z's. An extensive overview of the data-driven methods used to model the behavior of background processes is given as well. This analysis focuses on this type of direct electroweak supersymmetry production, and we set further constraints on the masses of chargino and neutralino particles.
Download or read book Search for Supersymmetry in pp Collisions at s 8 TeV with a Photon Lepton and Missing Transverse Energy written by Yutaro Iiyama and published by Springer. This book was released on 2017-06-14 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Ph.D. thesis is a search for physics beyond the standard model (SM) of particle physics, which successfully describes the interactions and properties of all known elementary particles. However, no particle exists in the SM that can account for the dark matter, which makes up about one quarter of the energy-mass content of the universe. Understanding the nature of dark matter is one goal of the CERN Large Hadron Collider (LHC). The extension of the SM with supersymmetry (SUSY) is considered a promising possibilities to explain dark matter. The nominated thesis describes a search for SUSY using data collected by the CMS experiment at the LHC. It utilizes a final state consisting of a photon, a lepton, and a large momentum imbalance probing a class of SUSY models that has not yet been studied extensively. The thesis stands out not only due to its content that is explained with clarity but also because the author performed more or less all aspects of the thesis analysis by himself, from data skimming to limit calculations, which is extremely rare, especially nowadays in the large LHC collaborations.
Download or read book Search for Supersymmetry in Proton proton Collisions at 7 TeV in Events with a Single Lepton B tagged Jets and Missing Transverse Momentum at the LHC Using Data Collected from the CMS Detector written by Wing Howard To and published by . This book was released on 2013 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a search for supersymmetry (SUSY) at the Large Hadron Collider using data collected in Run 2011 at center of mass energy of 7 TeV by the Compact Muon Solenoid detector with an integrated luminosity of 4.98 $fb{-1}$. First, the Large Hadron Collider is briefly described along with the Compact Muon Solenoid detector. Second, the Standard Model of particle physics is described which leads to the motivations for supersymmetry and its description. Finally, a search for supersymmetry in events with a single lepton, 2 b-tagged jets and missing transverse energy is documented in detail. The results are used to predict the yields from the standard model in bins missing transverse energy (\met) and total transverse hadronic energy (HT). Limits are set using these results using a minimal supergravity SUSY model and simplified model spectra SUSY model.
Download or read book Search for Supersymmetry at CMS in Events with B tagged Jets and Missing Transverse Energy at 8 TeV written by Kristen Flowers (Physicist) and published by . This book was released on 2015 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents results from a search for physics beyond the Standard Model, using 19.39 pb-1 of data collected by the CMS detector at the Large Hadron Collider, during its 2012 operation at √ s=8 TeV. It focuses on models of supersymmetry that lead to final states with multiple jets, especially those from b-quark decay, and a large amount of missing transverse momentum. The amounts of background from top-quark, W+jets, Z → nu[special character omitted], and multi-jet production are determined from data-driven techniques. In particular, this includes a novel estimation of the ETmiss spectrum from semi-leptonic tt ̄ decay, which takes advantage of the precise knowledge of the W boson polarization. Predicted yields are consistent with simulated Standard Model processes and the observed data. Since no evidence of new physics is observed, limits are placed on the rate of gluino pair production to a final state with four b-quarks and two neutralinos. This process is excluded at 95% CL for a gluino with mass 1225 GeV and a neutralino with mass up to 350 GeV.
Download or read book The Search for Supersymmetry in Hadronic Final States Using Boosted Object Reconstruction written by Giordon Stark and published by Springer Nature. This book was released on 2020-03-13 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis represents one of the most comprehensive and in-depth studies of the use of Lorentz-boosted hadronic final state systems in the search for signals of Supersymmetry conducted to date at the Large Hadron Collider. A thorough assessment is performed of the observables that provide enhanced sensitivity to new physics signals otherwise hidden under an enormous background of top quark pairs produced by Standard Model processes. This is complemented by an ingenious analysis optimization procedure that allowed for extending the reach of this analysis by hundreds of GeV in mass of these hypothetical new particles. Lastly, the combination of both deep, thoughtful physics analysis with the development of high-speed electronics for identifying and selecting these same objects is not only unique, but also revolutionary. The Global Feature Extraction system that the author played a critical role in bringing to fruition represents the first dedicated hardware device for selecting these Lorentz-boosted hadronic systems in real-time using state-of-the-art processing chips and embedded systems.
Download or read book Search for Supersymmetry with a Photon a Lepton and Missing Transverse Momentum in Pp Collisions at sqrt s written by and published by . This book was released on 2016 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our search for supersymmetry involving events with at least one photon, one electron or muon, and large missing transverse momentum has been performed by the CMS experiment. The data sample corresponds to an integrated luminosity of 19.7 fb-1 of pp collisions at √ s = 8 TeV, produced at the CERN LHC. No excess of events is observed beyond expectations from standard model processes. The result of the search is interpreted in the context of a general model of gauge-mediated supersymmetry breaking, where the charged and neutral winos are the next-to-lightest supersymmetric particles. Within this model, winos with a mass up to 360 GeV are excluded at the 95% confidence level. Also, two simplified models inspired by gauge-mediated supersymmetry breaking are also examined, and used to derive upper limits on the production cross sections of specific supersymmetric processes.
Download or read book Search for a Three Lepton and Missing Transverse Energy Signature of Supersymmetry Using a Multivariate Analysis written by Caleb Parnell Lampen and published by . This book was released on 2013 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for evidence of supersymmetry with a three lepton and missing transverse energy signature is presented. This signature is a possible final state from the associated production of a chargino and a neutralino, two particles predicted by supersymmetry. The study is performed on 2.06 fb−1 of 7 TeV center of mass energy proton-proton collisions, recorded with the ATLAS experiment at the Large Hadron Collider in 2011. A multivariate analysis is utilized, implementing a boosted decision tree classifier using lepton p(T), missing transverse energy, dilepton mass, and the razor variable R as inputs. No significant excess over the Standard Model prediction is observed, and upper limits are placed on the cross section times branching ratio of simplified models across a mass parameter space.
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 2014-06-24 with total page 178 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 Searching for Supersymmetry with Same sign Di leptons Using the Cms Experiment at the Large Hadron Collider written by Ronald C. Remington and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: After imposing the event selection requirements that define the signal region, 1 event is observed, which is statistically consistent with the total expected Standard Model background rate of 0.80 ± 0.33. Given this lack of an excess, exclusion limits are calculated on the parameter space of SUSY models with universal gaugino and scalar mass scales. The general limit on cross-section [delta] multiplied by branching ratio BR and the event selection acceptance A[superscript experiment] is [sigma] x BR x A[superscript experiment]
Download or read book Search for Supersymmetry in the One Lepton Channel at the LHC written by Arun Preston Luthra and published by . This book was released on 2013 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for supersymmetry was performed in events with one electron or muon, jets, and missing transverse momentum. The dataset was the first 5.0 fb [superscript -1] of [Square root of s] = 7 TeV proton-proton events from the Large Hadron Collider, as measured by the CMS detector in 2011. A data-driven method was used to estimate the background at high values of the transverse mass, where the suppression of the Standard Model backgrounds allows for relatively loose cuts on the jet activity. No excess above the expected background was observed, so a limit was set in the m0- m[subscript 1/2] plane of the CMSSM at tan [Beta] = 10, A0 = 0, and sgn(mu) = +1.
Download or read book Search for Supersymmetry in Events with a Lepton a Photon and Large Missing Transverse Energy in Pp Collisions at Sqrt s written by and published by . This book was released on 2011 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is performed for an excess of events, over the standard model expectations, with a photon, a lepton, and large missing transverse energy in pp collisions at sqrt(s) = 7 TeV. Such events are expected in many new physics models, in particular a supersymmetric theory that is broken via a gauge-mediated mechanism, when the lightest charged and neutral gauginos are mass degenerate. The data sample used in this search corresponds to an integrated luminosity of 35 inverse picobarns collected with the CMS detector at the LHC. No evidence of such an excess above the standard model backgrounds, dominated by W-gamma production, is found. The results are presented as 95% confidence level upper limits on the cross section for a benchmark gauge-mediated scenario, and are then converted into exclusion limits on the squark, gluino, and wino masses.
Download or read book Search for Gluino mediated Supersymmetry in Events with Bottom Quark Jets and Missing Transverse Energy with the Compact Muon Solenoid Detector at the Large Hadron Collider with Proton Proton Collisions at 8 TeV written by Harold Nguyen and published by . This book was released on 2013 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for physics beyond the standard model based on events with significant missing transverse energy, at least three jets, and at least one identified bottom-quark jet. The study is based on a sample of 19 fb-1 collected at 8 TeV with the CMS detector at the Large Hadron Collider in 2012. The background from standard model processes is evaluated using data control samples, and a global likelihood fit is performed. The data are found to be consistent with standard model processes, and the results are interpreted in the context of simplified models (SMS). Upper limits on the production cross sections of the T1bbbb and T1tttt SMS new physics scenarios are determined. Gluino masses up to 1170 GeV are excluded for the T1bbbb scenario and up to 1020 GeV for the T1tttt scenario, at 95% confidence level.
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 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 Supersymmetry Beyond Minimality written by Shaaban Khalil and published by CRC Press. This book was released on 2017-12-06 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supersymmetry (SUSY) is one of the most important ideas ever conceived in particle physics. It is a symmetry that relates known elementary particles of a certain spin to as yet undiscovered particles that differ by half a unit of that spin (known as Superparticles). Supersymmetric models now stand as the most promising candidates for a unified theory beyond the Standard Model (SM). SUSY is an elegant and simple theory, but its existence lacks direct proof. Instead of dismissing supersymmetry altogether, Supersymmetry Beyond Minimality: from Theory to Experiment suggests that SUSY may exist in more complex and subtle manifestation than the minimal model. The book explores in detail non-minimal SUSY models, in a bottom-up approach that interconnects experimental phenomena in the fermionic and bosonic sectors. The book considers with equal emphasis the Higgs and Superparticle sectors, and explains both collider and non-collider experiments. Uniquely, the book explores charge/parity and lepton flavour violation. Supersymmetry Beyond Minimality: from Theory to Experiment provides an introduction to well-motivated examples of such non-minimal SUSY models, including the ingredients for generating neutrino masses and/or relaxing the tension with the heavily constraining Large Hadron Collider (LHC) data. Examples of these scenarios are explored in depth, in particular the discussions on Next-to-Minimal Supersymmetric SM (NMSSM) and B-L Supersymmetric SM (BLSSM).
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.
