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Search For Pair Production Of Scalar Top Quarks In Jets And Missing Transverse Energy Channel With The D0 Detector
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Book Synopsis Search for Pair Production of Scalar Top Quarks in Jets and Missing Transverse Energy Channel with the D0 Detector by :
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.
Book Synopsis Search for Pair Production of Scalar Top Quarks in Jets and Missing Transverse Energy Channel with the D0 Detector by : Mansoora Shamim
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.
Book Synopsis Search for the Pair Production of Scalar Top Quarks in the Acoplanar Charm Jet Final State in P Anti-p Collisions at S**ư by :
Download or read book Search for the Pair Production of Scalar Top Quarks in the Acoplanar Charm Jet Final State in P Anti-p Collisions at S**ư written by and published by . This book was released on 2006 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for Direct Pair Production of Scalar Top Quarks in the Single- and Dilepton Channels in Proton-proton Collisions at $\sqrt{s}$ by :
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.
Book Synopsis Search for the Pair Production of Scalar Top Quarks in the Acoplanar Charm Jet Final State in P Anti-p Collisions at S**1/2 by :
Download or read book Search for the Pair Production of Scalar Top Quarks in the Acoplanar Charm Jet Final State in P Anti-p Collisions at S**1/2 written by and published by . This book was released on 2006 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for Scalar Top Quarks in the Acoplanar Charm Jets and Missing Transverse Energy Final State in P Anti-p Collisions at S**1/2 by :
Download or read book Search for Scalar Top Quarks in the Acoplanar Charm Jets and Missing Transverse Energy Final State in P Anti-p Collisions at S**1/2 written by and published by . This book was released on 2008 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for Scalar Top Quarks in the Acoplanar Charm Jets and Missing Transverse Energy Final State in P Anti-p Collisions at S**ư by :
Download or read book Search for Scalar Top Quarks in the Acoplanar Charm Jets and Missing Transverse Energy Final State in P Anti-p Collisions at S**ư written by and published by . This book was released on 2008 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement of the Top Quark Pair Production Cross-section in the Dilepton Channel Using Lepton Plus Track Selection and Identified B-jets by :
Download or read book Measurement of the Top Quark Pair Production Cross-section in the Dilepton Channel Using Lepton Plus Track Selection and Identified B-jets written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Using 1.0 fb^{-1} of data collected by the Collider Detector at Fermilab (CDF) from Run II of the Fermilab Tevatron, we measure the top-antitop production cross-section in events with two leptons, significant missing transverse energy, and at least jets, at least one of which is identified as a b-jet. As the Run II dataset grows, more stringent tests of Standard Model predictions for the top quark sector are becoming possible. The dilepton channel, where both top quarks decay t-> W b ->l nu b, is of particular interest due to its high purity. Use of an isolated track as the second lepton significantly increases the dilepton acceptance, at the price of some increase in background, particularly from W + jets events where one of the jets is identified as a lepton. To control the increase in background we add to the event selection the requirement that at least one of the jets be identified as a b-jet, reducing the background contribution from all sources. Assuming a branching ratio of BR(W->l nu) = 10.8% and a top mass of m_top = 175 GeV/c^{2} the measured cross-section is sigma = (10.5 +/- 1.8 stat. +/- 0.8 syst. +/- 0.6 lumi.) pb.
Book Synopsis A Search for the Pair Production of Scalar Top Quarks in Hadronic Final States with the CMS Detector by : Nickolas W. McColl
Download or read book A Search for the Pair Production of Scalar Top Quarks in Hadronic Final States with the CMS Detector written by Nickolas W. McColl and published by . This book was released on 2015 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Observation of Single Top Quark Production by :
Download or read book Observation of Single Top Quark Production written by and published by . This book was released on 2009 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The author reports on the observation of electroweak production of single top quarks in p{bar p} collisions at (square root)s = 1.96 Tev using 2.3 fb−1 of data collected with the D0 detector at the fermilab Tevatron Collider. Using events containing an isolated electron or muon, missing transverse energy, two, three or four jets, with one or two of them identified as originating from the fragmentation of a b quark, the measured cross section for the process p{bar p} --> tb + X, tqb + X is 3.94 ± 0.88 pb (for a top quark mass of 170 GeV). the probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10−7, corresponding to a 5.0 standard deviation significance. Using the same dataset, the measured cross sections for the t- and the s-channel processes when determined simultaneously with no assumption on their relative production rate are 3.14{sub -0.80}{sup +0.94} pb and 1.05 ± 0.81 pb respectively, consistent with standard model expectations. The measured t-channel cross section has a significance of 4.8 standard deviations, representing the first evidence for the production of an individual single top process to be detected.
Book Synopsis Search for Admixture of Scalar Top Quarks in the T Anti-t Lepton+jets Final State at S**1/2 by :
Download or read book Search for Admixture of Scalar Top Quarks in the T Anti-t Lepton+jets Final State at S**1/2 written by and published by . This book was released on 2009 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for pair production of the lightest supersymmetric partner of the top quark, {tilde t}1, is performed in the lepton+jets channel using 0.9 fb−1 of data collected by the D0 experiment. Kinematic differences between {tilde t}1{bar {tilde t}}1 and the dominant top quark pair production background are used to separate the two processes. First limits from Run II of the Fermilab Tevatron Collider for the scalar top quark decaying to a chargino and a b quark ({tilde t}1 2!{tilde {chi}}1 b) are obtained for scalar top quark masses of 130-190 GeV and chargino masses of 90-150 GeV.
Book Synopsis Search for Electroweak Top Quark Production in the Electron + Jets Channel in the D0 Experiment at the Tevatron by : Emmanuel Busato
Download or read book Search for Electroweak Top Quark Production in the Electron + Jets Channel in the D0 Experiment at the Tevatron written by Emmanuel Busato and published by . This book was released on 2005 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electroweak Production of the Top Quark in the Run II of the D0 Experiment by : Benoit Clement
Download or read book Electroweak Production of the Top Quark in the Run II of the D0 Experiment written by Benoit Clement and published by . This book was released on 2006 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work exposed in this thesis deals with the search for electroweak production of top quark (single top) in proton-antiproton collisions at {radical}s = 1.96 TeV. This production mode has not been observed yet. Analyzed data have been collected during the Run II of the D0 experiment at the Fermilab Tevatron collider. These data correspond to an integrated luminosity of 370 pb{sup -1}. In the Standard Model, the decay of a top quark always produce a high momentum bottom quark. Therefore bottom quark jets identification plays a major role in this analysis. The large lifetime of b hadrons and the subsequent large impact parameters relative to the interaction vertex of charged particle tracks are used to tag bottom quark jets. Impact parameters of tracks attached to a jet are converted into the probability for the jet to originate from the primary vertex. This algorithm has a 45% tagging efficiency for a 0.5% mistag rate. Two processes (s and t channels) dominate single top production with slightly different final states. The searched signature consists in 2 to 4 jets with at least one bottom quark jet, one charged lepton (electron or muon) and missing energy accounting for a neutrino. This final state is background dominated and multivariate techniques are needed to separate the signal from the two main backgrounds: associated production of a W boson and jets and top quarks pair production. The achieved sensitivity is not enough to reach observation and we computed upper limits at the 95% confidence level at 5 pb (s-channel) and 4.3 pb (t-channel) on single top production cross-sections.
Book Synopsis Search for Admixture of Scalar Top Quarks in the T Anti-t Lepton+jets Final State at S**ư by :
Download or read book Search for Admixture of Scalar Top Quarks in the T Anti-t Lepton+jets Final State at S**ư written by and published by . This book was released on 2009 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for pair production of the lightest supersymmetric partner of the top quark, {tilde t}1, is performed in the lepton+jets channel using 0.9 fb−1 of data collected by the D0 experiment. Kinematic differences between {tilde t}1{bar {tilde t}}1 and the dominant top quark pair production background are used to separate the two processes. First limits from Run II of the Fermilab Tevatron Collider for the scalar top quark decaying to a chargino and a b quark ({tilde t}1 → {tilde {chi}}1 b) are obtained for scalar top quark masses of 130-190 GeV and chargino masses of 90-150 GeV.
Book Synopsis Search for Scalar Top Admixture in the T Anti-t Lepton+Jets Channel at by :
Download or read book Search for Scalar Top Admixture in the T Anti-t Lepton+Jets Channel at written by and published by . This book was released on 2007 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search has been performed for scalar top quark pair production in the lepton+jets channel in (almost equal to)1 fb−1 of data. Kinematic differences between the exotic stop-stopbar and the dominant ttbar process are used to separate the two possible contributions. For scalar top quark masses of 145-175 GeV and chargino masses of 105-135 GeV we obtain upper cross section limits at 95% confidence level for stop-stopbar production that are a factor of (almost equal to)7-12 higher than expected for the Minimal Supersymmetric Standard Model (MSSM).
Book Synopsis Search for Pair Production of Scalar Top Quarks Decaying to a Tau Lepton and a B Quark in Ppbar Collisions at Sqrt{s} by :
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.
