Download or read book Search for Pair Production of the Scalar Top Quark in the Electron muon Final State written by and published by . This book was released on 2010 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Search for Pair Production of Scalar Top Quarks Decaying to a Tau Lepton and a B Quark in Ppbar Collisions at Sqrt s written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the results of a search for pair production of scalar top quarks ({tilde t}1) in an R-parity violating supersymmetric scenario using 322 pb−1 of p{bar p} collisions at √s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. We assume each {tilde t}1 decays into a? lepton and a b quark with a branching ratio?, and that the final state contains either an electron or a muon from a leptonic? decay, a hadronically decaying? lepton, and two or more jets. Two candidate events pass our final selection criteria, consistent with the expectation from standard model processes. We present upper limits on the cross section times branching ratio squared?({tilde t}1{bar {tilde t}}1) x?2 as a function of the stop mass m({tilde t}1). Assuming? = 1, we set a 95% confidence level limit m({tilde t}1)> 153 GeV=c2 obtained using a next-to-leading order cross section. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark decaying into a? lepton and a b quark.
Download or read book Search for Pair Production of Scalar Top Quarks Decaying to A Lepton and a B Quark in 1 96 TeV P bar p Collisions written by and published by . This book was released on 2008 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: I present the results of a search for pair production of scalar top quarks ($ ilde{t}$1) in an R-parity violating supersymmetric scenario using 322 pb-1 of p{bar p} collisions at √s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each $ ilde{t}$1 decays into a ? lepton and a b quark, with branching ratio ?, and search for final states containing either an electron or a muon from a leptonic ? decay, a hadronically decaying ? lepton, and two or more jets. Two candidate events pass my final selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared ?($ ilde{t}$1$ ilde{t}$1) x ?2 as a function of the stop mass m($ ilde{t}$1). Assuming ? = 1, I set a 95% confidence level limit m($ ilde{t}$1) > 153 GeV=c2. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a ? lepton and a b quark.
Download or read book Search for Direct Scalar Top Pair Production in Final States with Two Tau Leptons in Pp Collisions at S written by Ewan Chin Hill and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ATLAS Experiment at the CERN Large Hadron Collider is a particle physics experiment to study fundamental particles and their interactions at very high energies. Supersymmetry is a theory of new physics beyond the Standard Model of particle physics. A search for directly produced pairs of the supersymmetric partner of the top quark was performed using 20 fb^-1 of proton--proton collision data at a centre of mass energy of 8 TeV taken in 2012. The search targeted a model where the supersymmetric partner of the top quark (``scalar top'') decays via the supersymmetric partner of the tau lepton (``scalar tau'') into the supersymmetric partner of the graviton (``gravitino''). Scalar top candidates were searched for in pp collision events with either two hadronically decaying taus, two light leptons (electrons or muons), or one hadronically decaying tau and one light lepton. The numbers of events passing the analysis selection criteria agree with the Standard Model expectations. Exclusion limits at the 95% confidence level were set as a function of the scalar top and scalar tau masses. Depending on the scalar tau mass, ranging from the 87 GeV limit set by the LEP experiments to a few GeV below the scalar top mass, lower limits between 490 GeV and 640 GeV were placed on the scalar top mass within the model considered.
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.
Download or read book Search for Pair Production of Scalar Top Quarks Decaying to a tau Lepton and a beta Quark in 1 96 tev Pp Collisions written by Vadim Gennadyevich Khotilovich and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I present the results of a search for pair production of scalar top quarks (t̃1) in an R-parity violating supersymmetric scenario using 322 pb−1 of pp collisions at [square root]s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each t̃1 decays into a [tau] lepton and a [beta] quark, with branching ratio [beta], and search for nal states containing either an electron or a muon from a leptonic [tau] decay, a hadronically decaying [tau] lepton, and two or more jets. Two candidate events pass my nal selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared [sigma](t̃1t̃1) X [beta]2 as a function of the stop mass (mt̃1). Assuming [beta]= 1, I set a 95% condence level limit m(t̃1)> 153 GeV=c2. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a [tau] lepton and a [beta] quark.
Download or read book Supersymmetry And Unification Of Fundamental Interactions Proceedings Of The Ix International Conference Susy 01 written by A V Gladyshev and published by World Scientific. This book was released on 2002-03-28 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the theoretical, phenomenological and experimental aspects of supersymmetry in particle physics as well as its implications in cosmology.
Download or read book Proceedings of the IX International Conference on Supersymmetry and Unification of Fundamental Interactions written by D. I. Kazakov and published by World Scientific. This book was released on 2002 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the theoretical, phenomenological and experimental aspects of supersymmetry in particle physics as well as its implications in cosmology.
Download or read book Search for Direct Pair Production of Scalar Top Quarks in the Single and Dilepton Channels in Proton proton Collisions at sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book A Search for the Lightest Supersymmetric Partner of the Top Quark at written by and published by . This book was released on 2010 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ({tilde t}1) in 5.4 ± 0.3 fb−1 of data from the D0 detector at a p{bar p} center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. 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 new exclusion limits at the 95% C.L. are set for a portion of the (m{sub {tilde t}1}, m{sub {tilde {nu}}}) mass plane.
Download or read book Search for Scalar Charm Quark Pair Production in math Display written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a dedicated search for pair production of scalar partners of charm quarks are reported. The search is based on an integrated luminosity of 20.3 fb-1 of pp collisions at √s=8 TeV recorded with the ATLAS detector at the LHC. The search is performed using events with large missing transverse momentum and at least two jets, where the two leading jets are each tagged as originating from c quarks. The events containing isolated electrons or muons are vetoed. In an R-parity-conserving minimal supersymmetric scenario in which a single scalar-charm state is kinematically accessible, and where it decays exclusively into a charm quark and a neutralino, 95% confidence-level upper limits are obtained in the scalar-charm-neutralino mass plane such that, neutralino masses below 200 GeV, scalar-charm masses up to 490 GeV are excluded.
Download or read book Searches for the Supersymmetric Partner of the Top Quark Dark Matter and Dark Energy at the ATLAS Experiment written by Nicolas Maximilian Köhler and published by Springer Nature. This book was released on 2019-09-13 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical observations implying the existence of Dark Matter and Dark Energy, which are not described by the Standard Model (SM) of particle physics, have led to extensions of the SM predicting new particles that could be directly produced at the Large Hadron Collider (LHC) at CERN. Based on 2015 and 2016 ATLAS proton-proton collision data, this thesis presents searches for the supersymmetric partner of the top quark, for Dark Matter, and for DarkEnergy, in signatures with jets and missing transverse energy. Muon detection is key to some of the most important LHC physics results, including the discovery of the Higgs boson and the measurement of its properties. The efficiency with which muons can be detected with the ATLAS detector is measured using Z boson decays. The performance of high-precision Monitored Drift Tube muon chambers under background rates similar to the ones expected for the High Luminosity-LHC is studied.
Download or read book Search for Scalar Charm Quark Pair Production in Pp Collisions at S written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a dedicated search for pair production of scalar partners of charm quarks are reported. The search is based on an integrated luminosity of 20.3 fb–1 of pp collisions at √s=8 TeV recorded with the ATLAS detector at the LHC. The search is performed using events with large missing transverse momentum and at least two jets, where the two leading jets are each tagged as originating from c quarks. The events containing isolated electrons or muons are vetoed. In an R-parity-conserving minimal supersymmetric scenario in which a single scalar-charm state is kinematically accessible, and where it decays exclusively into a charm quark and a neutralino, 95% confidence-level upper limits are obtained in the scalar-charm–neutralino mass plane such that, neutralino masses below 200 GeV, scalar-charm masses up to 490 GeV are excluded.
Download or read book Search for Dark Matter with the ATLAS Detector written by Johanna Gramling and published by Springer. This book was released on 2018-08-01 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses searches for Dark Matter at the CERN’s LHC, the world’s most powerful accelerator. It introduces the relevant theoretical framework and includes an in-depth discussion of the Effective Field Theory approach to Dark Matter production and its validity, as well as an overview of the formalism of Simplified Dark Matter models. Despite overwhelming astrophysical evidence for Dark Matter and numerous experimental efforts to detect it, the nature of Dark Matter still remains a mystery and has become one of the hottest research topics in fundamental physics. Two searches for Dark Matter are presented, performed on data collected with the ATLAS experiment. They analyze missing-energy final states with a jet or with top quarks. The analyses are explained in detail, and the outcomes and their interpretations are discussed, also in view of the precedent analysis of theoretical approaches. Given its depth of coverage, the book represents an excellent reference guide for all physicists interested in understanding the theoretical and experimental considerations relevant to Dark Matter searches at the LHC.
Download or read book Scalar Boson Decays to Tau Leptons written by Cécile Caillol and published by Springer. This book was released on 2017-11-15 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a study of the scalar sector in the standard model (SM), as well as various searches for an extended scalar sector in theories beyond the SM (BSM). The first part of the thesis details the search for an SM Higgs boson decaying to taus, and produced by gluon fusion, vector boson fusion, or associated production with a vector boson, leading to evidence for decays of the Higgs boson to taus. In turn, the second part highlights several searches for an extended scalar sector, with scalar boson decays to taus. In all of the analyses presented, at least one scalar boson decays to a pair of taus. The results draw on data collected by the Compact Muon Solenoid (CMS) detector during proton–proton collisions with a center-of-mass energy of 7 or 8 TeV.
Download or read book Search for Pair Production of Scalar Top Quarks in Jets and Missing Transverse Energy Channel with the D0 Detector written by Mansoora Shamim and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Search for Pair Production of Scalar Top Quarks in Jets and Missing Transverse Energy Channel with the D0 Detector written by and published by . This book was released on 2008 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes a search for the pair production of scalar top quarks, {tilde t}1, using a luminosity of 995 pb−1 of data collected in p{bar p} collisions with the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy (square root)s = 1.96 TeV. Both scalar top quarks are assumed to decay into a charm quark and a neutralino, {tilde {chi}}1°, where {tilde {chi}}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 t}1 and {tilde {chi}}1° masses are excluded at the 95% confidence level that substantially extend the domain excluded by previous searches. With the theoretical uncertainty on the {tilde t}1 pair production cross section taken into account, the largest limit for m{sub {tilde t}1} is m{sub {tilde t}1}> 150 GeV, for m{sub {tilde {chi}}1°} = 65 GeV.
