Observation of Top Quarks in the Dilepton Decay Channel T[anti T][yields] E([mu][upsilon][sub E([mu][tau][upsilon][sub[tau] B[anti B] Using Hadronic Tau Decays at CDF.

Download Observation of Top Quarks in the Dilepton Decay Channel T[anti T][yields] E([mu][upsilon][sub E([mu][tau][upsilon][sub[tau] B[anti B] Using Hadronic Tau Decays at CDF. PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (684 download)

DOWNLOAD NOW!


Book Synopsis Observation of Top Quarks in the Dilepton Decay Channel T[anti T][yields] E([mu][upsilon][sub E([mu][tau][upsilon][sub[tau] B[anti B] Using Hadronic Tau Decays at CDF. by :

Download or read book Observation of Top Quarks in the Dilepton Decay Channel T[anti T][yields] E([mu][upsilon][sub E([mu][tau][upsilon][sub[tau] B[anti B] Using Hadronic Tau Decays at CDF. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a search for dilepton events from top decays with one electron or muon and a hadronically decaying[tau] lepton. The total acceptance x efficiency is (O.119[+-] 0.014([ital stat]))% for[ital m[sub top]]= 175 GeV. In 110 pb[sup -1] of data we expect 1.1[+-] 0. 3([ital stat]) signal events and a total background of 1.96[+-] 0.35([ital stat]) events while observing 4 candidate events (2[ital e][tau] and 2[mu][tau]). Three events are[ital b]-tagged. If a tag is required, the probability for the estimated background (0.225[+-] 0.011 events) to fluctuate to[>=] 3 events is 0.13% (3.0[sigma]). A first measurement of the[ital t[anti t]] production cross section based on these events yields[sigma][sub t[anti t]]= 15.6[sup+18. 6][sub -13.2]([ital stat]) pb.

Observation of Top Quarks in the Dilepton Decay Channel T{anti T} 2!e([mu][upsilon]{sub E({mu})} [tau][upsilon]{sub {tau}} B{anti B} Using Hadronic Tau Decays at CDF.

Download Observation of Top Quarks in the Dilepton Decay Channel T{anti T} 2!e([mu][upsilon]{sub E({mu})} [tau][upsilon]{sub {tau}} B{anti B} Using Hadronic Tau Decays at CDF. PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.:/5 (893 download)

DOWNLOAD NOW!


Book Synopsis Observation of Top Quarks in the Dilepton Decay Channel T{anti T} 2!e([mu][upsilon]{sub E({mu})} [tau][upsilon]{sub {tau}} B{anti B} Using Hadronic Tau Decays at CDF. by :

Download or read book Observation of Top Quarks in the Dilepton Decay Channel T{anti T} 2!e([mu][upsilon]{sub E({mu})} [tau][upsilon]{sub {tau}} B{anti B} Using Hadronic Tau Decays at CDF. written by and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a search for dilepton events from top decays with one electron or muon and a hadronically decaying [tau] lepton. The total acceptance x efficiency is (O.119 ± 0.014({ital stat}))% for {ital m{sub top}} = 175 GeV. In 110 pb−1 of data we expect 1.1 ± 0. 3({ital stat}) signal events and a total background of 1.96 ± 0.35({ital stat}) events while observing 4 candidate events (2 {ital e}[tau] and 2 [mu][tau]). Three events are {ital b}-tagged. If a tag is required, the probability for the estimated background (0.225 ± 0.011 events) to fluctuate to ≥ 3 events is 0.13% (3.0 [sigma]). A first measurement of the {ital t{anti t}} production cross section based on these events yields [sigma]{sub t{anti t}} = 15.6{sup +18. 6}{sub -13.2}({ital stat}) pb.

Observation of Top Quark Pairs in the Dilepton Decay Channel Using Electrons, Muons, and Taus

Download Observation of Top Quark Pairs in the Dilepton Decay Channel Using Electrons, Muons, and Taus PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 456 pages
Book Rating : 4.:/5 (89 download)

DOWNLOAD NOW!


Book Synopsis Observation of Top Quark Pairs in the Dilepton Decay Channel Using Electrons, Muons, and Taus by : Marcus Hohlmann

Download or read book Observation of Top Quark Pairs in the Dilepton Decay Channel Using Electrons, Muons, and Taus written by Marcus Hohlmann and published by . This book was released on 1997 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Recent Results on Top Quark Physics at CDF.

Download Recent Results on Top Quark Physics at CDF. PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (684 download)

DOWNLOAD NOW!


Book Synopsis Recent Results on Top Quark Physics at CDF. by :

Download or read book Recent Results on Top Quark Physics at CDF. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the latest results on the top quark obtained by the CDF experiment using a data sample of about 110 pb[sup -1]. The data sample has been collected at the FermiLab Tevatron Collider with p[anti p] collisions at[radical]s= 1.8 TeV. We briefly describe the candidate event selection and then discuss the production cross section determination and the mass measurement. Combining the results from the channels with at least one W decaying leptonically into an electron or muon, we measure[sigma][sub t[anti t]]= 7.5[sup+1.9][sub -1.6] pb. Our best measured value for the top mass gives M[sub t]= 176.8[+-]6.5 GeV/c[sup 2]. We also report on the observation of t[anti t] production in the all hadronic decay channel using kinematic selection and b identification, and in the channel containing one hadronically decaying[tau] lepton. Finally we discuss the kinematics of top events and measure the matrix element[vert-bar]V[sub tb][vert-bar]=1.12[+-]0.12.

A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II.

Download A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II. PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 272 pages
Book Rating : 4.3/5 (91 download)

DOWNLOAD NOW!


Book Synopsis A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II. by : Bodhitha Anjalike Jayatilaka

Download or read book A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II. written by Bodhitha Anjalike Jayatilaka and published by . This book was released on 2006 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Precision Measurement of Top Quark Mass in Dilepton Channel

Download Precision Measurement of Top Quark Mass in Dilepton Channel PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 9 pages
Book Rating : 4.:/5 (316 download)

DOWNLOAD NOW!


Book Synopsis Precision Measurement of Top Quark Mass in Dilepton Channel by : Bodhitha Jayatilaka

Download or read book Precision Measurement of Top Quark Mass in Dilepton Channel written by Bodhitha Jayatilaka and published by . This book was released on 2006 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present recent measurements of the top quark mass using events collected at the CDF and D0 detectors from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. These analyses are performed using events consistent with the decay channel t{bar t} {yields} {bar b}{ell}{sup -}{bar v}{sub {ell}}b{ell}' + v'{sub {ell}}, or the dilepton channel. 230-360 pb{sup -1} of data are used.

Measurement of the Top Quark Pair Production Cross Section in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV, Hadronic Top Decays with the D0 Detector

Download Measurement of the Top Quark Pair Production Cross Section in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV, Hadronic Top Decays with the D0 Detector PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 193 pages
Book Rating : 4.:/5 (873 download)

DOWNLOAD NOW!


Book Synopsis Measurement of the Top Quark Pair Production Cross Section in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV, Hadronic Top Decays with the D0 Detector by :

Download or read book Measurement of the Top Quark Pair Production Cross Section in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV, Hadronic Top Decays with the D0 Detector written by and published by . This book was released on 2009 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of the six quarks in the standard model the top quark is by far the heaviest: 35 times more massive than its partner the bottom quark and more than 130 times heavier than the average of the other five quarks. Its correspondingly small decay width means it tends to decay before forming a bound state. Of all quarks, therefore, the top is the least affected by quark confinement, behaving almost as a free quark. Its large mass also makes the top quark a key player in the realm of the postulated Higgs boson, whose coupling strengths to particles are proportional to their masses. Precision measurements of particle masses for e.g. the top quark and the W boson can hereby provide indirect constraints on the Higgs boson mass. Since in the standard model top quarks couple almost exclusively to bottom quarks (t 2!Wb), top quark decays provide a window on the standard model through the direct measurement of the Cabibbo-Kobayashi-Maskawa quark mixing matrix element V{sub tb}. In the same way any lack of top quark decays into W bosons could imply the existence of decay channels beyond the standard model, for example charged Higgs bosons as expected in two-doublet Higgs models: t 2!Hb. Within the standard model top quark decays can be classified by the (lepton or quark) W boson decay products. Depending on the decay of each of the W bosons, t{bar t} pair decays can involve either no leptons at all, or one or two isolated leptons from direct W 2!e{bar {nu}}{sub e} and W 2![mu]{bar {nu}}{sub {mu}} decays. Cascade decays like b 2!Wc 2!e{bar {nu}}{sub e}c can lead to additional non-isolated leptons. The fully hadronic decay channel, in which both Ws decay into a quark-antiquark pair, has the largest branching fraction of all t{bar t} decay channels and is the only kinematically complete (i.e. neutrino-less) channel. It lacks, however, the clear isolated lepton signature and is therefore hard to distinguish from the multi-jet QCD background. It is important to measure the cross section (or branching fraction) in each channel independently to fully verify the standard model. Top quark pair production proceeds through the strong interaction, placing the scene for top quark physics at hadron colliders. This adds an additional challenge: the huge background from multi-jet QCD processes. At the Tevatron, for example, t{bar t} production is completely hidden in light q{bar q} pair production. The light (i.e. not bottom or top) quark pair production cross section is six orders of magnitude larger than that for t{bar t} production. Even including the full signature of hadronic t{bar t} decays, two b-jets and four additional jets, the QCD cross section for processes with similar signature is more than five times larger than for t{bar t} production. The presence of isolated leptons in the (semi)leptonic t{bar t} decay channels provides a clear characteristic to distinguish the t{bar t} signal from QCD background but introduces a multitude of W- and Z-related backgrounds.

Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment

Download Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 145 pages
Book Rating : 4.:/5 (727 download)

DOWNLOAD NOW!


Book Synopsis Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment by :

Download or read book Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment written by and published by . This book was released on 2010 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the most massive observed fundamental subatomic particle, and at the Tevatron accelerator is produced mostly in top-antitop (t{bar t}) quark pairs from the collisions of protons and anti-protons. Each top quark decays into a bottom quark and a W boson. The W boson can then decay into a pair of quarks, or into a charged lepton and a neutrino. The various decays can be broken up into three different channels based on the number of leptons from the decay of the W bosons: all-jets (with no leptons), lepton+jets (with one lepton), and dilepton (with two leptons). This dissertation will present a measurement of the top quark mass in the dilepton channel. The dilepton channel is characterized by two leptons, two neutrinos and two b-quarks. The neutrinos are not directly observed, but their absence is felt as missing transverse momentum (p{sub T}) in the detector. The combination of two leptons and large p{sub T} produces an easily isolated signal, giving the dilepton channel a high signal over background ratio. Having two neutrinos means that we cannot know what the transverse momenta of either neutrino is. This means that even if we knew the momenta of the leptons and b-quarks perfectly, we would be unable to reconstruct the mass of the top quark. This measurement gets around this problem by scanning over all possible values of the top mass, finding all consistent t{bar t} combinations, assigning a kinematic weight to each, and then adding the weights for each combination at a given possible top mass. The lepton momenta, jet momenta, and p{sub T} are only known to within some finite precision, so for a given top mass, I also vary each of these momenta within their resolutions and add the weights for a given possible top mass. After scanning over possible top masses, I choose the top mass with the largest sum of weights m{sub t}{sup max} as an observable for the event. I then perform a template based likelihood fit of m{sub t} using m{sub t}{sup max}. I analyze 322 candidate events collected by the D0 detector, and obtain a top quark mass of: m{sub t} = 174.8 ± 3.1 GeV.

Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment

Download Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 246 pages
Book Rating : 4.:/5 (699 download)

DOWNLOAD NOW!


Book Synopsis Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment by : Daniel Boline

Download or read book Top Quark Mass in Events with Two Charged Leptons at the D0 Experiment written by Daniel Boline and published by . This book was released on 2010 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The top quark is the most massive observed fundamental subatomic particle, and at the Tevatron accelerator is produced mostly in top-antitop ( tt ) quark pairs from the collisions of protons and anti-protons. Each top quark decays into a bottom quark and a W boson. The W boson can then decay into a pair of quarks, or into a charged lepton and a neutrino. The various decays can be broken up into three different channels based on the number of leptons from the decay of the W bosons: all-jets (with no leptons), lepton+jets (with one lepton), and dilepton (with two leptons). This dissertation will present a measurement of the top quark mass in the dilepton channel. The dilepton channel is characterized by two leptons, two neutrinos and two b-quarks. The neutrinos are not directly observed, but their absence is felt as missing transverse momentum ([Special characters omitted.] ) in the detector. The combination of two leptons and large [Special characters omitted.] produces an easily isolated signal, giving the dilepton channel a high signal over background ratio. Having two neutrinos means that we cannot know what the transverse momenta of either neutrino is. This means that even if we knew the momenta of the leptons and b-quarks perfectly, we would be unable to reconstruct the mass of the top quark. This measurement gets around this problem by scanning over all possible values of the top mass, finding all consistent tt combinations, assigning a kinematic weight to each, and then adding the weights for each combination at a given possible top mass. The lepton momenta, jet momenta, and [Special characters omitted.] are only known to within some finite precision, so for a given top mass, I also vary each of these momenta within their resolutions and add the weights for a given possible top mass. After scanning over possible top masses, I choose the top mass with the largest sum of weights [Special characters omitted.] as an observable for the event. I then perform a template based likelihood fit of m t using [Special characters omitted.] . I analyze 322 candidate events collected by the DØ detector, and obtain a top quark mass of: [Special characters omitted.]

Observation of the Top Quark

Download Observation of the Top Quark PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 9 pages
Book Rating : 4.:/5 (683 download)

DOWNLOAD NOW!


Book Synopsis Observation of the Top Quark by :

Download or read book Observation of the Top Quark written by and published by . This book was released on 1995 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The D0 collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at (square root)s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb−1. We have searched for t{bar t} production in the dilepton and single lepton decay channels, with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 " 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 x 10−6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 19921{sup +19} (stat.) "22 (syst.) GeV/c2 and its production cross section to be 6.4 " 2.2 pb.

Search for Vector-like T Quarks Decaying to Top Quarks and Higgs Bosons in the All-hadronic Channel Using Jet Substructure

Download Search for Vector-like T Quarks Decaying to Top Quarks and Higgs Bosons in the All-hadronic Channel Using Jet Substructure PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 48 pages
Book Rating : 4.:/5 (925 download)

DOWNLOAD NOW!


Book Synopsis Search for Vector-like T Quarks Decaying to Top Quarks and Higgs Bosons in the All-hadronic Channel Using Jet Substructure by :

Download or read book Search for Vector-like T Quarks Decaying to Top Quarks and Higgs Bosons in the All-hadronic Channel Using Jet Substructure written by and published by . This book was released on 2015 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb−1 collected with the CMS detector in proton-proton collisions at √s = 8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. Upper limits on the production cross section of a T quark with mass between 500 and 1000 GeV/c2 are derived. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c2 at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.

Measurement of the Top-quark Mass in All-hadronic Decays in P Anti-p Collisions at CDF II.

Download Measurement of the Top-quark Mass in All-hadronic Decays in P Anti-p Collisions at CDF II. PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (727 download)

DOWNLOAD NOW!


Book Synopsis Measurement of the Top-quark Mass in All-hadronic Decays in P Anti-p Collisions at CDF II. by :

Download or read book Measurement of the Top-quark Mass in All-hadronic Decays in P Anti-p Collisions at CDF II. written by and published by . This book was released on 2006 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the top-quark mass, M{sub tpo}, in the all-hadronic decay channel t{bar t} --> WbW−{bar b} --> q1{bar q}2bq3{bar q}4{bar b}. The analysis is performed using 310 pb−1 of (square root)s = 1.96 TeV p{bar p} collisions collected with the CDF II detector using a multi-jet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value of M{sub top} = 177.1 ± 4.9(stat.) ± 4.7(syst.) GeV/c2.

Measurements of the Top Anti-top Production Cross Section and Top Quark Mass in the Hadronically Decaying Tau + Jets Decay Channel at CDF

Download Measurements of the Top Anti-top Production Cross Section and Top Quark Mass in the Hadronically Decaying Tau + Jets Decay Channel at CDF PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 212 pages
Book Rating : 4.:/5 (773 download)

DOWNLOAD NOW!


Book Synopsis Measurements of the Top Anti-top Production Cross Section and Top Quark Mass in the Hadronically Decaying Tau + Jets Decay Channel at CDF by : Daryl Curtis Hare

Download or read book Measurements of the Top Anti-top Production Cross Section and Top Quark Mass in the Hadronically Decaying Tau + Jets Decay Channel at CDF written by Daryl Curtis Hare and published by . This book was released on 2011 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Measurements and Searches with Top Quarks

Download Measurements and Searches with Top Quarks PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 254 pages
Book Rating : 4.:/5 (727 download)

DOWNLOAD NOW!


Book Synopsis Measurements and Searches with Top Quarks by :

Download or read book Measurements and Searches with Top Quarks written by and published by . This book was released on 2008 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1995 the last missing member of the known families of quarks, the top quark, was discovered by the CDF and D0 experiments at the Tevatron, a proton-antiproton collider at Fermilab near Chicago. Until today, the Tevatron is the only place where top quarks can be produced. The determination of top quark production and properties is crucial to understand the Standard Model of particle physics and beyond. The most striking property of the top quark is its mass--of the order of the mass of a gold atom and close to the electroweak scale--making the top quark not only interesting in itself but also as a window to new physics. Due to the high mass, much higher than of any other known fermion, it is expected that the top quark plays an important role in electroweak symmetry breaking, which is the most prominent candidate to explain the mass of particles. In the Standard Model, electroweak symmetry breaking is induced by one Higgs field, producing one additional physical particle, the Higgs boson. Although various searches have been performed, for example at the Large Electron Positron Collider (LEP), no evidence for the Higgs boson could yet be found in any experiment. At the Tevatron, multiple searches for the last missing particle of the Standard Model are ongoing with ever higher statistics and improved analysis techniques. The exclusion or verification of the Higgs boson can only be achieved by combining many techniques and many final states and production mechanisms. As part of this thesis, the search for Higgs bosons produced in association with a top quark pair (t{bar t}H) has been performed. This channel is especially interesting for the understanding of the coupling between Higgs and the top quark. Even though the Standard Model Higgs boson is an attractive candidate, there is no reason to believe that the electroweak symmetry breaking is induced by only one Higgs field. In many models more than one Higgs boson are expected to exist, opening even more channels to search for charged or neutral Higgs bosons. Depending on its mass, the charged Higgs boson is expected to decay either into top quarks or be the decay product of a top quark. For masses below the top quark mass, the top decay into a charged Higgs boson and a b quark can occur at a certain rate, additionally to the decays into W bosons and a b quark. The different decays of W and charged Higgs bosons can lead to deviations of the observed final number of events in certain final states with respect to the Standard Model expectation. A global search for charged Higgs bosons in top quark pair events is presented in this thesis, resulting in the most stringent limits to-date. Besides the decay of top quarks into charged Higgs or W bosons, new physics can also show up in the quark part of the decay. While in the Standard Model the top quark decays with a rate of about 100% into a W boson and a b quark, there are models where the top quark can decay into a W boson and a non-b quark. The ratio of branching fractions in which the top quark decays into a b quark over the branching fractions in which the top quark decays into all quarks is measured as part of this thesis, yielding the most precise measurement today. Furthermore, the Standard Model top quark pair production cross section is essential to be known precisely since the top quark pair production is the main background for t{bar t}H production and many other Higgs and beyond the Standard Model searches. However, not only the search or the test of the Standard Model itself make the precise measurement of the top quark pair production cross section interesting. As the cross section is calculated with high accuracy in perturbative QCD, a comparison of the measurement to the theory expectation yields the possibility to extract the top quark mass from the cross section measurement. Although many dedicated techniques exist to measure the top quark mass, the extraction from the cross section represents an important complementary measurement. The latter is briefly discussed in this thesis and compared to direct top mass measurements. The goal of this thesis is the improved understanding of the top quark sector and its use as a window to new physics. Techniques are extended and developed to measure the top quark pair production cross section simultaneously with the ratio of branching fractions, the t{bar t}H cross section or the rate with which top quarks decay into charged Higgs bosons. Some of the results are then taken to extract more information. The cross section measurement is used to extract the top quark mass, and the ratio of the top quark pair production cross sections in different final states, yielding a limit on non-Standard Model top quark decays.

Search for the Top Quark in Dilepton Decay Modes at

Download Search for the Top Quark in Dilepton Decay Modes at PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (685 download)

DOWNLOAD NOW!


Book Synopsis Search for the Top Quark in Dilepton Decay Modes at by :

Download or read book Search for the Top Quark in Dilepton Decay Modes at written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present preliminary results on the search for the top quark in p[bar p] collisions at [radical]s = 1.8 TeV by the D0 collaboration at the Fermilab Tevatron. The results are based on an integrated luminosity of 13.5 pb[sup [minus]1] of data collected by the D0 detector during the 1992-3 Tevatron collider run. They have searched for Standard Model t[bar t] decays into the dilepton decay modes ee + X, e[mu] + X and [mu][mu] + X. No significant signal is observed for top quark production in these channels. They find one candidate event in the e[mu] + X channel and no events in the other two channels with an estimated non-top background of 0.76 [+-] 0.16 events.

Studies of the Top Quark with the D0 Detector

Download Studies of the Top Quark with the D0 Detector PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 10 pages
Book Rating : 4.:/5 (683 download)

DOWNLOAD NOW!


Book Synopsis Studies of the Top Quark with the D0 Detector by :

Download or read book Studies of the Top Quark with the D0 Detector written by and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The observation of the top quark by the D0 experiment, at Fermilab's Tevatron proton-antiproton collider, is briefly reviewed. The analysis of the top quark mass in the lepton plus jets decay channels, resulting in m{sub t} (almost equal to) 200 GeV/c2 is reviewed; and a preliminary mass analysis from the dilepton decay channels resulting in m{sub t} = 145 " 25 (statistical) " 20 (systematic) GeV/c2 is presented. These mass measurements are compared with Standard Model limits from CERN's LEP experiments and the published CDF measurement. Preliminary observation of top quark-W boson correlation is shown.

Precision Measurements of the Top Quark Mass and Width with the D0 Detector

Download Precision Measurements of the Top Quark Mass and Width with the D0 Detector PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (873 download)

DOWNLOAD NOW!


Book Synopsis Precision Measurements of the Top Quark Mass and Width with the D0 Detector by :

Download or read book Precision Measurements of the Top Quark Mass and Width with the D0 Detector written by and published by . This book was released on 2010 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of the top quark in 1995 at the Fermliab Tevatron Collider, top quark properties have been measured with ever higher precision. In this article, recent measurements of the top quark mass and its width using up to 3.6 fb−1 of D0 data are summarized. Different techniques and final states have been examined and no deviations within these measurements have been observed. In addition to the direct measurements, a measurement of the top quark mass from its production cross section and a measurement of the top-antitop quark mass difference are discussed. With a mass of 173.3 ± 1.1 GeV, the top quark is the heaviest of all known fundamental particles. Due to the high mass, its Yukawa coupling is close to unity suggesting that it may play a special role in electroweak symmetry breaking. Precise measurements of both, the W boson and the top quark mass, constrain the mass of the yet unobserved Higgs boson and allow to restrict certain extensions of the Standard Model. At the Tevatron collider with a center-of-mass energy of 1.96 TeV, 85% of the top quark pairs are produced in quark-antiquark annihilation; 15% originate from gluon fusion. Top quarks are predicted to decay almost exclusively to a W boson and a bottom quark. According to the number of hadronic W decays, top events are classified into all-jets, lepton+jets and dilepton events. The lepton+jets channel is characterized by four jets, one isolated, energetic charged lepton and missing transverse energy. With 30%, the branching fraction of the lepton+jets channel is about seven times larger than the one of the dilepton channel whereas the signal to background ratio is about three times smaller. The main background in this final state comes from W +jets events. Instrumental background arises from events in which a jet is misidentified as an electron and events with heavy hadrons that decay into leptons which pass the isolation requirements. The topology of the dilepton channel is described by two jets, two isolated, energetic charged leptons and significant missing transverse energy from the undetected neutrinos. The main background are Z + jets and diboson events (WW/WZ/ZZ+jets) as well as instrumental background as characterized above. At the D0 experiment, different techniques are used to measure the top quark mass. They are summarized in the following sections together with the first measurement of the top anti-top quark mass difference and the first precise determination of the top quark width.