Download or read book A Measurement of the Partial Width of the Z0 Boson Into B Quarks and the Forward backward Asymmetry in the Reaction Ee Z0 Bb Using Inclusive Electrons written by Paul Robert Schenk and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Measurement of the Partial Width of the Z Boson Into B Quarks and the Forward backward Asymmetry in the Reaction E E Z Bb Using Inclusive Electrons written by Paul Robert Schenk and published by . This book was released on 1992 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Energy Physics Index written by and published by . This book was released on 1990 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Polarized Forward Backward Asymmetry of Z0 Bb Using a Lifetime Tag and Momentum Weighted Track Charge written by and published by . This book was released on 2004 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a direct measurement of the parity violating parameter A{sub b} by analyzing the left right forward backward asymmetry of b quarks in ee− --> Z° --> b{bar b}. The SLD experiment observes hadronic decays of Z° bosons produced at resonance in collisions of longitudinally polarized electrons and unpolarized positrons at the SLC. Heavy flavor decays of the Z° are identified by using the topologically reconstructed mass of B hadrons. The asymmetry A{sub b} is measured with a self calibrating technique employing momentum weighted track charge from both hemispheres in the tagged events. From our 1994-1995 sample of 3.6 pb−1 of ee− annihilation data with a luminosity weighted average e− polarization of 77%, and our 1993 sample of 1.8 pb−1 with a luminosity-weighted polarization of 63%, we obtain A{sub b} = 0.911 " 0.045(stat.) " 0.045(syst.).

Download or read book Measurement of the Polarized Forward backward Asymmetry of Z B bar B Using a Lifetime Tag and Momentum weighted Track Charge written by and published by . This book was released on 1995 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a direct measurement of the parity-violating parameter A{sub b} by analyzing the left-right forward-backward asymmetry of b quarks in ee− --> Z{sup o} --> b{bar b}. The SLD experiment observes hadronic decays of Z{sup o} bosons produced at resonance in collisions of longitudinally polarized electrons and unpolarized positrons at the SLC. Heavy flavor decays of the Z{sup o} are identified by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and precise tracking from SLD. The asymmetry A{sub b} is measured with a self-calibrating technique employing momentum-weighted track charge from both hemispheres in the tagged events. From our 1994--1995 sample of 3.6 pb−1 of ee− annihilation data with a luminosity-weighted average e− polarization of 77.3%, and our 1993 sample of 1.8 pb−1 with a luminosity-weighted polarization of 63.1%, we obtain A{sub b}(preliminary) = 0.843 " 0.046(stat.) " 0.051(syst.).

Download or read book Z Boson Asymmetry Measurements at the Tevatron written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present measurements of the forward-backward asymmetry (A_fb) in dilepton pair decays of Z bosons produced in ppbar collisions using the full Tevatron dataset. The CDF experiment extracts a value for the effective weak mixing angle parameter sin^{2}\theta^{l}_{eff} of 0.2315 +/- 0.0010 from the A_fb distribution of dimuon events in 9.2 fb^{-1} of integrated luminosity. From dielectron events in 9.7 fb^{-1} of data, the D0 experiment finds sin^{2}\theta^{l}_{eff} = 0.23106 +/- 0.00053, the world's most precise measurement of sin^{2}\theta^{l}_{eff} from hadron colliders and with light quark couplings.

Download or read book Extraction of the Width of the W Boson from a Measurement of the Ratio of the W and Z Cross Sections written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation reports on measurements of inclusive cross sections times branching fractions into electrons for W and Z bosons produced in p[anti p] collisions at[radical]s= 1.8 TeV. From an integrated luminosity of 84.5 pb[sup[minus]1] recorded in 1994--1995 by the D0 detector at the Fermilab Tevatron[Lambda] the cross sections are measured to be[sigma]p[anti p][r-arrow] W+ X[center-dot] B(W[r-arrow] e[nu])= 2,310[+-] 10 (stat)[+-] 50 (Syst)[+-] 100 (lum) pb and[sigma](p[anti p][r-arrow] Z+ X)[center-dot] B(Z[r-arrow] ee)= 221[+-] 3 (stat)[+-] 4 (Syst)[+-] 10 (lum) pb. The cross section ratio R is determined to be[sigma](p[anti p][r-arrow] W+ X)[center-dot] B(W[r-arrow] e[nu])/[sigma](p[bar p][r-arrow] Z+ X)[center-dot] B(Z[r-arrow] ee)= 10.43[+-] 0.15 (stat)[+-] 0.20 (syst)[+-] 0.10 (NLO)[Lambda] and R is used to determine B(W[r-arrow] e[nu])= 0.1044[+-] 0.0015 (stat)[+-] 0.0020 (syst)[+-] 0.0017 (theory)[+-] 0.0010 (NLO)[Lambda] and[Lambda][sub W]= 2.169[+-] 0.031 (stat)[+-] 0.042 (syst)[+-] 0.041 (theory)[+-] 0.022 (NLO) GeV. The latter is used to set a 95% confidence level upper limit on the partial decay width of the W boson into non-standard model final states[Lambda][Lambda][sub W][sup inv][Lambda] of 0.213 GeV.

Download or read book Measurement of the Z Boson Branching Fraction Into Hadrons Containing Bottom Quarks written by J. Frederic Kral and published by . This book was released on 1990 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Strange Quark Forward backward Asymmetry Around the Z0 Peak written by Edouard Boudinov and published by . This book was released on 2000 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Left right Forward backward Asymmetry of Heavy Quarks Measured with Jet Charge and with Leptons at the SLD written by and published by . This book was released on 1994 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present direct measurements of the left-right asymmetry of b- and c-quarks from the decay of Z° bosons produced in the annihilation of longitudinally polarized electrons and unpolarized positrons. Two complementary techniques are presented: (1) Z° --> b{bar b} decays are tagged using track impact parameters with b{bar b} discrimination provided by momentum-weighted track charge; (2) semileptonic b-decays are tagged using high p and p{sub T} muons and electrons. The preliminary results from their 1993 data sample are: A{sub b} = 0.93 " 0.13 " 0.13 for the jet charge and A{sub b} = 0.93 " 0.14 " 0.09, and A{sub c} = 0.40 " 0.23 " 0.20 for the leptons, where the first error is statistical and the second systematic.

Download or read book MEASUREMENT of the Forward Backward Asymmetry in Z bb bar and Z cc bar Decays with Leptons Extras written by S. SCHAEL and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Z boson Branching Fraction Into Hadrons Containing Bottom Quarks written by and published by . This book was released on 1990 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: We use the Mark II detector to study Z decays into bottom quark-anti-quark pairs, leading to the production of bottom hadrons. The Z bosons are formed in ee− annihilation at the SLC at center-of-mass energies between 89 and 93 GeV. We identify events containing semileptonic decays of bottom hadrons by detecting isolated leptons, i.e leptons with high transverse momenta relative to the nearest hadronic jet. Using isolated electrons and muons, we measure the B-hadron semileptonic branching ratio times the fraction of hadronic Z decays which contain bottom hadrons, B(B 2!Xl[nu]){center dot}[Gamma](Z 2!b{bar b})/[Gamma](Z 2!had) = 0.025 {sub -0.009}{sup +0.100} {plus minus} 0.005, where we have listed the statistical errors followed by the systematic error. Assuming B(B 2!X(ell)[nu]) = 11% {plus minus} 1%, we measure [Gamma](Z 2!b{bar b})/[Gamma](Z 2!had) = 0.23 {sub -0.09}{sup +0.11}, in good agreement with the standard-model prediction of 0.22. We find [Gamma](Z 2!b{bar b}) = 0.40 {sub -0.16}{sup +0.19} GeV. 83 refs., 34 figs., 19 tabs.

Download or read book Higgs Boson Decays into a Pair of Bottom Quarks written by Cecilia Tosciri and published by Springer Nature. This book was released on 2021-10-22 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery in 2012 of the Higgs boson at the Large Hadron Collider (LHC) represents a milestone for the Standard Model (SM) of particle physics. Most of the SM Higgs production and decay rates have been measured at the LHC with increased precision. However, despite its experimental success, the SM is known to be only an effective manifestation of a more fundamental description of nature. The scientific research at the LHC is strongly focused on extending the SM by searching, directly or indirectly, for indications of New Physics. The extensive physics program requires increasingly advanced computational and algorithmic techniques. In the last decades, Machine Learning (ML) methods have made a prominent appearance in the field of particle physics, and promise to address many challenges faced by the LHC. This thesis presents the analysis that led to the observation of the SM Higgs boson decay into pairs of bottom quarks. The analysis exploits the production of a Higgs boson associated with a vector boson whose signatures enable efficient triggering and powerful background reduction. The main strategy to maximise the signal sensitivity is based on a multivariate approach. The analysis is performed on a dataset corresponding to a luminosity of 79.8/fb collected by the ATLAS experiment during Run-2 at a centre-of-mass energy of 13 TeV. An excess of events over the expected background is found with an observed (expected) significance of 4.9 (4.3) standard deviation. A combination with results from other \Hbb searches provides an observed (expected) significance of 5.4 (5.5). The corresponding ratio between the signal yield and the SM expectation is 1.01 +- 0.12 (stat.)+ 0.16-0.15(syst.). The 'observation' analysis was further extended to provide a finer interpretation of the V H(H → bb) signal measurement. The cross sections for the VH production times the H → bb branching ratio have been measured in exclusive regions of phase space. These measurements are used to search for possible deviations from the SM with an effective field theory approach, based on anomalous couplings of the Higgs boson. The results of the cross-section measurements, as well as the constraining of the operators that affect the couplings of the Higgs boson to the vector boson and the bottom quarks, have been documented and discussed in this thesis. This thesis also describes a novel technique for the fast simulation of the forward calorimeter response, based on similarity search methods. Such techniques constitute a branch of ML and include clustering and indexing methods that enable quick and efficient searches for vectors similar to each other. The new simulation approach provides optimal results in terms of detector resolution response and reduces the computational requirements of a standard particles simulation.

Download or read book Measurement of the Polarized Forward backward Asymmetry of B Quarks Using Momentum weighted Track Charge at SLD written by and published by . This book was released on 1995 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a direct measurement of the parity-violating parameter A{sub b} by analyzing the polarized forward-backward asymmetry of b quarks in ee− --> Z° --> b{bar b}. Data were taken at the Stanford Linear Accelerator Center (SLAC), with the Stanford Large Detector (SLD), which records the products of ee− interactions at a center of mass energy (square root)s = 91.2 GeV/c2 at the SLAC Linear Collider (SLC). The SLC/SLD experimental apparatus provides a unique and ideal environment for measuring electroweak asymmetries. Heavy flavor decays of the Z° were identified inclusively by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and SLD's precise tracking detectors. Two analysis techniques for measuring A{sub b} are presented: a binned fit to the left-right forward-backwards asymmetry of tagged events signed with momentum-weighted track charge, and a self-calibrating maximum-likelihood technique using momentum-weighted charge from the two hemispheres in each tagged event. From our 1994-1995 sample of 3.6 pb−1, having a luminosity-weighted average e− polarization of 77.3%, and our 1993 sample of 1.8 pb−1, having a luminosity-weighted polarization of 63.1%, we obtain A{sub b} = 0.848 " 0.046(stat.) " 0.050(syst.).

Download or read book Measurement of the Polarized Forward backward Asymmetry of B Quarks at SLD written by and published by . This book was released on 1997 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a direct measurement of the parity-violating parameter A{sub b} using the Left-Right Forward-Backward asymmetry of b{anti b} pair production at the Z° pole. The measurement was done at the Stanford Linear Accelerator Center (SLAC) using data from the SLAC Large Detector (SLD). The authors take advantage of the high polarization of the SLAC Linear Collider (SLC) electron beam. To identify heavy flavor decays of the Z°, they use a b-tag based on the topological reconstruction of the mass of the B vertex. Discrimination between the b and {anti b} quark directions is provided by a self-calibrating jet-charge technique. This technique allows calibration of the analyzing power from data and gives a much reduced model dependence. Based on the 1994--95 (1993) sample of 100,000 (50,000) Z° decays recorded with an electron beam polarization of P{sub e} = 77% (63%), they have obtained A{sub b} = 0.911 " 0.045(stat) " 0.045(syst). This value is in goo d agreement with the Standard Model.

Download or read book Polarization at LEP written by and published by . This book was released on 1988 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: