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Measurement of Top Anti-top Cross Section in Proton - Anti-proton Collider at {u221A}s

Measurement of Top Anti-top Cross Section in Proton - Anti-proton Collider at {u221A}s PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 353

Book Description
Discovery of the top quark in 1995 at the Fermilab Tevatron collider concluded a long search following the 1977 discovery of bottom (b) quark [1] and represents another triumph of the Standard Model (SM) of elementary particles. Top quark is one of the fundamental fermions in the Standard Model of electroweak interactions and is the weak-isospin partner of the bottom quark. A precise measurement of top pair production cross-section would be a test of Quantum Chromodynamics (QCD) prediction. Presently, Tevatron is the world's highest energy collider where protons (p) and anti-protons ($ar{p}$) collide at a centre of mass energy √s of 1.96 TeV. At Tevatron top (t) and anti-top ($ar{t}$) quarks are predominantly pair produced through strong interactions--quark annihilation (≅ 85%) and gluon fusion (≅ 15%). Due to the large mass of top quark, t or $ar{t}$ decays ( ̃10-25 sec) before hadronization and in SM framework, it decays to a W boson and a b quark with ̃100% branching ratio (BR). The subsequent decay of W boson determines the major signatures of t$ar{t}$ decay. If both W bosons (coming from t and $ar{t}$ decays) decay into leptons (viz., eve, ?v? or ?c?) the corresponding t$ar{t}$ decay is called dileptonic decay. Of all dileptonic decay modes of t$ar{t}$, the t$ar{t}$ → WWb$ar{b}$ → eve?v?b$ar{b}$ (e? channel) decay mode has the smallest background contamination from Z0 production or Drell-Yan process; simultaneously, it has the highest BR ( ̃3.16%) [2] amongst all dileptonic decay modes of t$ar{t}$. During Run I (1992-1996) of Tevatron, three e? candidate events were detected by D0 experiment, out of 80 candidate events (inclusive of all decay modes of t$ar{t}$). Due to the rarity of the t$ar{t}$ events, the measured cross-section has large uncertainty in its value (viz., 5.69 ± 1.21(stat) ± 1.04(sys) pb @ √s = 1.8 TeV measured by D0 [3]). This analysis presents a cross section measurement in e? channel utilizing ̃228 pb-1 of data collected by D0 experiment during Tevatron Run II (between June 2002 and April 2004).

Measurement of Top Anti-top Cross Section in Proton - Anti-proton Collider at {u221A}s

Measurement of Top Anti-top Cross Section in Proton - Anti-proton Collider at {u221A}s PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 353

Book Description
Discovery of the top quark in 1995 at the Fermilab Tevatron collider concluded a long search following the 1977 discovery of bottom (b) quark [1] and represents another triumph of the Standard Model (SM) of elementary particles. Top quark is one of the fundamental fermions in the Standard Model of electroweak interactions and is the weak-isospin partner of the bottom quark. A precise measurement of top pair production cross-section would be a test of Quantum Chromodynamics (QCD) prediction. Presently, Tevatron is the world's highest energy collider where protons (p) and anti-protons ($ar{p}$) collide at a centre of mass energy √s of 1.96 TeV. At Tevatron top (t) and anti-top ($ar{t}$) quarks are predominantly pair produced through strong interactions--quark annihilation (≅ 85%) and gluon fusion (≅ 15%). Due to the large mass of top quark, t or $ar{t}$ decays ( ̃10-25 sec) before hadronization and in SM framework, it decays to a W boson and a b quark with ̃100% branching ratio (BR). The subsequent decay of W boson determines the major signatures of t$ar{t}$ decay. If both W bosons (coming from t and $ar{t}$ decays) decay into leptons (viz., eve, ?v? or ?c?) the corresponding t$ar{t}$ decay is called dileptonic decay. Of all dileptonic decay modes of t$ar{t}$, the t$ar{t}$ → WWb$ar{b}$ → eve?v?b$ar{b}$ (e? channel) decay mode has the smallest background contamination from Z0 production or Drell-Yan process; simultaneously, it has the highest BR ( ̃3.16%) [2] amongst all dileptonic decay modes of t$ar{t}$. During Run I (1992-1996) of Tevatron, three e? candidate events were detected by D0 experiment, out of 80 candidate events (inclusive of all decay modes of t$ar{t}$). Due to the rarity of the t$ar{t}$ events, the measured cross-section has large uncertainty in its value (viz., 5.69 ± 1.21(stat) ± 1.04(sys) pb @ √s = 1.8 TeV measured by D0 [3]). This analysis presents a cross section measurement in e? channel utilizing ̃228 pb-1 of data collected by D0 experiment during Tevatron Run II (between June 2002 and April 2004).

Measurement of Top Anti-top Cross Section in Proton - Anti-proton Collider at S**(1/2)

Measurement of Top Anti-top Cross Section in Proton - Anti-proton Collider at S**(1/2) PDF Author: Prolay Kumar Mal
Publisher:
ISBN:
Category :
Languages : en
Pages : 353

Book Description
Discovery of the top quark in 1995 at the Fermilab Tevatron collider concluded a long search following the 1977 discovery of bottom (b) quark [1] and represents another triumph of the Standard Model (SM) of elementary particles. Top quark is one of the fundamental fermions in the Standard Model of electroweak interactions and is the weak-isospin partner of the bottom quark. A precise measurement of top pair production cross-section would be a test of Quantum Chromodynamics (QCD) prediction. Presently, Tevatron is the world's highest energy collider where protons (p) and anti-protons ({anti p}) collide at a centre of mass energy (ps) of 1.96 TeV. At Tevatron top (t) and anti-top ({anti t}) quarks are predominantly pair produced through strong interactions--quark annihilation ({approx_equal} 85%) and gluon fusion ({approx_equal} 15%). Due to the large mass of top quark, t or {anti t} decays ({approx} 10{sup -25} sec) before hadronization and in SM framework, it decays to a W boson and a b quark with {approx} 100% branching ratio (BR). The subsequent decay of W boson determines the major signatures of t{anti t} decay. If both W bosons (coming from t and {anti t} decays) decay into leptons (viz., ev{sub e}, {mu}{nu}{sub {mu}} or {tau}{nu}{sub {tau}}) the corresponding t{bar t} decay is called dileptonic decay. Of all dileptonic decay modes of t{bar t}, the t{bar t} {yields} WWb{anti b} {yields} ev{sub e}{mu}{nu}{sub {mu}}b{anti b} (e{mu} channel) decay mode has the smallest background contamination from Z{sup 0} production or Drell-Yan process; simultaneously, it has the highest BR ({approx} 3.16%) [2] amongst all dileptonic decay modes of t{bar t}. During Run I (1992-1996) of Tevatron, three e{mu} candidate events were detected by D0 experiment, out of 80 candidate events (inclusive of all decay modes of t{bar t}). Due to the rarity of the t{bar t} events, the measured cross-section has large uncertainty in its value (viz., 5.69 {+-} 1.21(stat) {+-} 1.04(sys) pb {at} {radical}s = 1.8 TeV measured by D0 [3]). This analysis presents a cross section measurement in e{mu} channel utilizing {approx} 228 pb{sup -1} of data collected by D0 experiment during Tevatron Run II (between June 2002 and April 2004).

A Measurement of the Top-antitop Production Cross Section in Proton-antiproton Collisions at Center of Mass Energy

A Measurement of the Top-antitop Production Cross Section in Proton-antiproton Collisions at Center of Mass Energy PDF Author: Ulysses Allen Grundler
Publisher: ProQuest
ISBN: 9780549908883
Category :
Languages : en
Pages : 119

Book Description
I present a measurement of the tt¯ production cross section at s = 1.96 TeV using 2034 pb-1 of CDF Run II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes a t → Wb branching fraction of 100 percent. Events consistent with tt¯ decay are found by identifying jets containing heavy-flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 248 candidate events and an expected background of 86.8+/-5.6 events, I measure a production cross section of 8.7+/-1.1+0.9-0.8+/-0.6 pb, in agreement with the Standard Model.

Measurements of the Top - Anti-top Production Cross Section at S**(1/2)

Measurements of the Top - Anti-top Production Cross Section at S**(1/2) PDF Author: Joseph Francis Kozminski
Publisher:
ISBN:
Category :
Languages : en
Pages : 218

Book Description
The first measurement of the top-antitop production cross section in proton-antiproton collisions at {radical}s = 1.96 TeV using 243 pb{sup -1} of data collected with the D0 detector at Fermilab is presented. In this analysis, only the dielectron final state is considered. Five events are observed, and 0.93 background events are expected. The measured cross section, after accounting for the expected branching ratio to the dielectron channel, is {sigma}{sub t{bar t}} = 14.9{sub -7.0}{sup +9.4}(stat){sub -1.8}{sup +2.5}(syst) {+-} 1.0 (lumi) pb, which agrees with the predicted cross section for top quarks with a mass of 175 GeV. In addition, a first-pass at a measurement of the top mass using the neutrino-weighting method is presented. This measurement is also performed in the dielectron channel using the five events observed in the cross section measurement.

Measurement of the P Anti-p --] T Anti-t Production Cross Section at S**ư

Measurement of the P Anti-p --] T Anti-t Production Cross Section at S**ư PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10

Book Description
A measurement of the top quark pair production cross section in proton anti-proton collisions at an interaction energy of √s = 1.96 TeV is presented. This analysis uses 405 pb−1 of data collected with the D0 detector at the Fermilab Tevatron Collider. Fully hadronic t{bar t} decays with final states of six or more jets are separated from the multijet background using secondary vertex tagging and a neural network. The t{bar t} cross section is measured as?{sub t{bar t}} = 4.5{sub -1.9}{sup +2.0}(stat){sub -1.1}{sup +1.4}(syst) ± 0.3(lumi) pb for a top quark mass of m{sub t} = 175 GeV/c2.

A Measurement of the Production Cross Section of Top-antitop Pairs in Proton-antiproton Collisions at a Center of Mass of 1.96 TeV Using Secondary Vertex B-tagging

A Measurement of the Production Cross Section of Top-antitop Pairs in Proton-antiproton Collisions at a Center of Mass of 1.96 TeV Using Secondary Vertex B-tagging PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
Abstract Not Provided.

Measurement of the T Anti-t Production Cross Section in P Anti-p Collisions at {u221A}s

Measurement of the T Anti-t Production Cross Section in P Anti-p Collisions at {u221A}s PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 172

Book Description
The direct observation of the top quark was first achieved at the Tevatron proton anti-proton collider at Fermilab. This discovery completed the third generation quark sector where the top quark is expected to accompany the bottom quark in the weak isospin doublet. This dissertation discusses the experimental verification of the production cross section as predicted by the Standard Model. A measurement of the t$ar{t}$ production cross section using 107.9 pb-1 of p$ar{p}$ collisions at √s = 1.96 TeV collected with the Collider Detector at Fermilab between March of 2003 and June of 2003 is presented. The measurement focuses on the t$ar{t}$ production in the ''lepton plus jets'' final state in which one of the W bosons from the t$ar{t}$ decay subsequently decays leptonically to an electron or a muon, and the other decays hadronically. The B-tagging technique which utilizes the precision silicon detector tracking is used to enhance the signal for t$ar{t}$ events relative to the background through identification of the bottom quark from its measurable lifetime. The t$ar{t}$ production cross section is measured to be ?t$ar{t}$ = 4.5 ± 1.4(stat) ± 0.8(sys) pb.

A Measurement of the Production Cross Section of Top-antitop Pairs in Proton-antiproton Collisions at a Center of Mass of 1.96 TeV Using Secondary Vertexb-tagging

A Measurement of the Production Cross Section of Top-antitop Pairs in Proton-antiproton Collisions at a Center of Mass of 1.96 TeV Using Secondary Vertexb-tagging PDF Author: Henri Bachacou
Publisher:
ISBN:
Category :
Languages : en
Pages : 232

Book Description
A measurement of the t{bar t} pair production cross section is presented using 162 pb{sup -1} of data collected by the CDF experiment during Run II at the Tevatron. t{bar t} events in the lepton+jets channel are isolated by identifying electrons and muons, reconstructing jets and transverse missing energy, and identifying b jets with a secondary vertex tagging algorithm. The efficiency of the algorithm is measured in a control sample using a novel technique that is less dependent on the simulation. For a top quark mass of 175 GeV/c{sup 2}, a cross section of {sigma}{sub t{bar t}} = 5.6{sub -1.1}{sup +1.2}(stat.){sub -0.6}{sup +0.9}(syst.)pb is measured.

Measurements of the T$\bar{t}$ Production Cross Section at {u221A}s

Measurements of the T$\bar{t}$ Production Cross Section at {u221A}s PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 218

Book Description
The first measurement of the top-antitop production cross section in proton-antiproton collisions at √s = 1.96 TeV using 243 pb-1 of data collected with the D0 detector at Fermilab is presented. In this analysis, only the dielectron final state is considered. Five events are observed, and 0.93 background events are expected. The measured cross section, after accounting for the expected branching ratio to the dielectron channel, is ?t$ar{t}$ = 14.9$+9.4top{-7.0}$(stat)$+2.5top{-1.8}${sup +2.5}(syst) ± 1.0 (lumi) pb, which agrees with the predicted cross section for top quarks with a mass of 175 GeV. In addition, a first-pass at a measurement of the top mass using the neutrino-weighting method is presented. This measurement is also performed in the dielectron channel using the five events observed in the cross section measurement.

Measurement of the P Anti-p --] T Anti-t Production Cross Section at S**1/2

Measurement of the P Anti-p --] T Anti-t Production Cross Section at S**1/2 PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10

Book Description
A measurement of the top quark pair production cross section in proton anti-proton collisions at an interaction energy of √s = 1.96 TeV is presented. This analysis uses 405 pb−1 of data collected with the D0 detector at the Fermilab Tevatron Collider. Fully hadronic t{bar t} decays with final states of six or more jets are separated from the multijet background using secondary vertex tagging and a neural network. The t{bar t} cross section is measured as [sigma]{sub t{bar t}} = 4.5{sub -1.9}{sup +2.0}(stat){sub -1.1}{sup +1.4}(syst) ± 0.3(lumi) pb for a top quark mass of m{sub t} = 175 GeV/c2.