A Search For The Pair Production Of Scalar Top Quarks In Hadronic Final States With The Cms Detector PDF Download
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| Author | : Nickolas W. McColl |
| Publisher | : |
| Total Pages | : 242 |
| Release | : 2015 |
| Genre | : |
| ISBN | : 9781339218786 |
Download A Search for the Pair Production of Scalar Top Quarks in Hadronic Final States with the CMS Detector Book in PDF, ePub and Kindle
The sensitivity of this search to models with a top squark decaying to jets and a neutralino through a on-shell top quark extends to 775 GeV in top squark mass and to 650 GeV in models with a top squark decaying through an intermediate chargino.
| Author | : Takuya Nobe |
| Publisher | : Springer |
| Total Pages | : 229 |
| Release | : 2015-11-30 |
| Genre | : Science |
| ISBN | : 9811000034 |
Download Search for Scalar Top Quarks and Higgsino-Like Neutralinos Book in PDF, ePub and Kindle
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.
| Author | : Reyer Edmond Band |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2020 |
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| ISBN | : |
Download A Search for Vector-like Quarks with the CMS Detector at the LHC Book in PDF, ePub and Kindle
A search for the pair-production of vector-like T and B quarks decaying into an all-hadronic final state is presented. Data corresponding to 35.9 fb−1 collected by CMS during 2016 at the LHC are analyzed. The analysis makes use of jet substructure and mass drop techniques to identify jets coming from boosted W decays, and is optimized for the discovery of a T quark decaying to a bottom quark and a W boson. The scalar sum of jet momenta is tested for the presence of signal, and upper limits at the 95% confidence level are established on the existence of the T and B for masses less than 1040 GeV and 1070 GeV respectively.
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| Total Pages | : |
| Release | : 2016 |
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Download Search for Direct Pair Production of Scalar Top Quarks in the Single- and Dilepton Channels in Proton-proton Collisions at $\sqrt{s}$ Book in PDF, ePub and Kindle
Results are reported from a search for the top squark $ \tilde{t}_1 $, the lighter of the two supersymmetric partners of the top quark. The data sample corresponds to 19.7 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} =$ 8 TeV collected with the CMS detector at the LHC. The search targets $ \tilde{t}_1 \to \mathrm{b} \tilde{\chi}^{\pm}_1$ and $ \tilde{t}_1 \to \mathrm{t}^{(*)} \tilde{\chi}^0_1$ decay modes, where $\tilde{\chi}^{\pm}_1$ and $\tilde{\chi}^0_1$ are the lightest chargino and neutralino, respectively. The reconstructed final state consists of jets, b jets, missing transverse energy, and either one or two leptons. Leading backgrounds are determined from data. No significant excess in data is observed above the expectation from standard model processes. The results exclude a region of the two-dimensional plane of possible $ \tilde{t}_1 $ and $\tilde{\chi}^0_1 $ masses. The highest excluded $ \tilde{t}_1 $ and $ \tilde{\chi}^0_1$ masses are about 700 GeV and 250 GeV, respectively.
| 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 | : Samuel Jones |
| Publisher | : Springer Nature |
| Total Pages | : 223 |
| Release | : 2020-08-27 |
| Genre | : Science |
| ISBN | : 3030542882 |
Download Searching for Squarks Book in PDF, ePub and Kindle
This thesis focuses on searches for squarks with the ATLAS detector in "compressed" scenarios where the scalar top is very close in mass to the lightest supersymmetric particle. These models are theoretically appealing because the presence of a quasi-degenerate scalar top enhances the self-annihilation cross-section of the lightest supersymmetric particle, acting therefore as a regulator of the dark matter relic density. Two main analyses are presented: the first is a search for scalar tops decaying to charm quarks. The identification of jets originating from the charm quark is very challenging due to its short lifetime. The calibration of tools for charm-tagging has paved the way to measuring the decay of the Higgs boson to pairs of charm quarks. The second analysis presented is the development of a novel technique for reconstructing low momentum b-hadrons. This tool has enabled the ATLAS collaboration to explore topologies that were previously inaccessible.
| Author | : Roman Pasechnik |
| Publisher | : Frontiers Media SA |
| Total Pages | : 180 |
| Release | : 2020-09-03 |
| Genre | : Science |
| ISBN | : 2889639908 |
Download Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like? Book in PDF, ePub and Kindle
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
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| Total Pages | : 8 |
| Release | : 2010 |
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Download Search for Pair Production of the Scalar Top Quark in the Electron+muon Final State Book in PDF, ePub and Kindle
We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ({tilde t}1) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb−1. The scalar top quarks are assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}), and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and improved exclusion limits at the 95% C.L. are set in the (M{sub {tilde t}1}, M{sub {tilde {nu}}}) mass plane.
| Author | : Mansoora Shamim |
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| Total Pages | : |
| Release | : 2008 |
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Download Search for Pair Production of Scalar Top Quarks in Jets and Missing Transverse Energy Channel with the D0 Detector Book in PDF, ePub and Kindle
This dissertation describes a search for the pair production of scalar top quarks, tilde[subscript] 1, using a luminosity of 995 pb[superscript-1] of data collected in p[bar over]p collisions with the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy sqrt[s] = 1.96 TeV. Both scalar top quarks are assumed to decay into a charm quark and a neutralino, [tilde chi superscript 0 subscript 1] where [(tilde chi superscript 0 subscript 1)] is the lightest supersymmetric particle. This leads to a final state with two acoplanar charm jets and missing transverse energy. The yield of such events in data is found to be consistent with the expectations from known standard model processes. Sets of tilde [subscript 1] and tilde chi [superscript 0 subscript 1] masses are excluded at the 95% confidence level that substantially extend the domain excluded by previous searches. With the theoretical uncertainty on the pair production cross section taken into account, the largest limit for m[subscript tilde subscript 1] is m[subscript tilde chi subscript 1> 150 GeV, for m [subscript tilde chi negative 0 subscript 1]= 65 GeV.
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| Total Pages | : 9 |
| Release | : 2006 |
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Download Search for the Pair Production of Scalar Top Quarks in the Acoplanar Charm Jet Final State in P Anti-p Collisions at S**ư Book in PDF, ePub and Kindle
A search for the pair production of scalar top quarks, {bar t}, has been performed in 360 pb−1 of data from p{bar p} collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron collider. The {bar t} decay mode considered is {bar t} → c{bar {chi}}1°, where {bar {chi}}1° is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data show good agreement with the standard model expectation, and a 95% C.L. exclusion domain in the (m{sub {tilde t}}, m{sub {tilde {chi}}1°}) plane has been determined, extending the domain excluded by previous experiments.
