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Author: Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb−1 of data collected with the D0 detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W bosons at the 95% confidence level for several different W' boson masses. We exclude masses below 610 GeV for a W' boson with standard-model-like couplings, below 630 GeV for a W' boson with right-handed couplings that is allowed to decay to both leptons and quarks, and below 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.
Author: Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb−1 of data collected with the D0 detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W bosons at the 95% confidence level for several different W' boson masses. We exclude masses below 610 GeV for a W' boson with standard-model-like couplings, below 630 GeV for a W' boson with right-handed couplings that is allowed to decay to both leptons and quarks, and below 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
We search for the production of a heavy W(prime) gauge boson that decays to third generation quarks in 0.9 fb−1 of p{bar p} collisions at (square root)s = 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron collider. We find no significant excess in the final-state invariant mass distribution and set upper limits on the production cross section times branching fraction. For a left-handed W(prime) boson with SM couplings, we set a lower mass limit of 731 GeV. For right-handed W(prime) bosons, we set lower mass limits of 739 GeV if the W(prime) boson decays to both leptons and quarks and 768 GeV if the W(prime) boson decays only to quarks. We also set limits on the coupling of the W(prime) boson to fermions as a function of its mass.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
The authors present a measurement of the fraction f+ of right-handed W bosons produced in top quark decays, based on a candidate sample of t{bar t} events in the l+jets and dilepton decay channels corresponding to an integrated luminosity of 370 pb−1 collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider at √s = 1.96 TeV. They reconstruct the decay angle [theta]* for each lepton. By comparing the cos[theta]* distribution from the data with those for the expected background and signal for various values of f+, they find f+ = 0.056 ± 0.080(stat) ± 0.057(syst). (f+
Author: Publisher: ISBN: Category : Languages : en Pages : 42
Book Description
A search is performed for the production of a massive W' boson decaying to a top and a bottom quark. The data analysed correspond to an integrated luminosity of 19.7 fb$^{{u2013}1}$ collected with the CMS detector at the LHC in proton-proton collisions at $ \sqrt{s}=8 $ TeV. The hadronic decay products of the top quark with high Lorentz boost from the W' boson decay are detected as a single top flavoured jet. The use of jet substructure algorithms allows the top quark jet to be distinguished from standard model QCD background. Limits on the production cross section of a right-handed W' boson are obtained, together with constraints on the left-handed and right-handed couplings of the W' boson to quarks. The production of a right-handed W' boson with a mass below 2.02 TeV decaying to a hadronic final state is excluded at 95% confidence level. Furthermore, this mass limit increases to 2.15 TeV when both hadronic and leptonic decays are considered, and is the most stringent lower mass limit to date in the tb decay mode.
Author: Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb−1 sample of candidate t{bar t} events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider. We reconstruct the angle [theta]* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos [theta]* distribution finds that the fraction of longitudinal W bosons f0 = 0.390 ± 0.177 (stat.) ± 0.104 (syst.) and the fraction of right-handed W bosons f+ = 0.171 ± 0.102 (stat.) ± 0.058 (syst.), which is consistent at the 27% C.L. with the standard model.
Author: Herwig Schopper Publisher: World Scientific ISBN: 9814644161 Category : Science Languages : en Pages : 452
Book Description
The book is a compilation of the most important experimental results achieved during the past 60 years at CERN - from the mid-1950s to the latest discovery of the Higgs particle. Covering the results from the early accelerators at CERN to those most recent at the LHC, the contents provide an excellent review of the achievements of this outstanding laboratory. Not only presented is the impressive scientific progress achieved during the past six decades, but also demonstrated is the special way in which successful international collaboration exists at CERN.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A measurement of the polarization of the W boson from top quark decay is an excellent test of the V-A form of the charged-current weak interaction in the standard model. Since the longitudinal W boson is intimately related to the electroweak symmetry breaking mechanism, and the standard model gives a specific prediction for the fraction of longitudinal W bosons from top decays, it is of particular interest for study. This thesis presents a measurement of W boson polarization in top quark decay through an analysis of the cos [theta]* distribution in the lepton-plus-jets channel of t[bar t] candidate events from p[bar p] collisions at [radical]s = 1.96 TeV. This measurement uses an integrated luminosity of [approx]162 pb[sup -1] of data collected with the CDF Run II detector, resulting in 31 t[bar t] candidate events with at least one identified b jet. Using a binned likelihood fit to the cos [theta]* distribution from the t[bar t] candidate events found in this sample, the fraction of W bosons with longitudinal polarization is determined to be F[sub 0] = 0.99[sub -0.35][sup +0.29](stat.) [+-] 0.19(syst.), F[sub 0]> 0.33 [at] 95% CL. This result is consistent with the standard model prediction, given a top quark mass of 174.3 GeV/c[sup 2], of F[sub 0] = 0.701 [+-] 0.012.
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Author: Daniel P. Berdine
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Author: Herwig Schopper
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