Download or read book A Measurement of the Z Sup 0 Hadronic Branching Fraction to Bottom Quarks and the Charged Multiplicity of Bottom Quark Events Using Precision Vertex Detectors at E Sub Cm written by and published by . This book was released on 1992 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z° decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z° decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub -0.045}{sup +0.053} (stat) {sub -0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z° decays,?{bar n}{sub b} = 2.11 {plus minus} 1.82(stat) {plus minus} 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 {plus minus} 1.82 (stat) {plus minus} 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 {plus minus} 1.82 (stat) {plus minus} 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.
Download or read book A Measurement of the Z Hadronic Branching Fraction to Bottom Quarks and the Charged Multiplicity of Bottom Quark Events Using Precision Vertex Detectors at E sub Cm written by and published by . This book was released on 1992 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z° decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z° decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub -0.045}{sup +0.053} (stat) {sub -0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z° decays, [delta]{bar n}{sub b} = 2.11 ± 1.82(stat) ± 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 ± 1.82 (stat) ± 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 ± 1.82 (stat) ± 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Measurement of the Z0 Hadronic Branching Fraction to Bottom Quarks and the Charged Multiplicity of Bottom Quark Events Using Precision Vertex Detectors at Ecm written by Dale Steven Koetke and published by . This book was released on 1992 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Measurement of the Z Sup 0 Hadronic Branching Fraction to Bottom Quark and the Charged Multiplicity 91 GEV written by Dale Steven Koetke and published by . This book was released on 1992 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1993 with total page 1258 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1993 with total page 1290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
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 Branching Ratio of the Z0 Into Heavy Quarks written by and published by . This book was released on 2005 with total page 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 Measuring the Branching Fraction for Z Sup 0 Yields B B Using Precision Vertex Detectors written by and published by . This book was released on 1991 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the fraction of b{bar b} events in hadronic Z° decays, R{sub b{bar b}}, using the vertex detector system of the Mark 2 detector at the SLC. We tab b{bar b} events by requiring at least three tracks with significant impact parameters. This tag is 50% efficient and results in a sample of 85% purity. We find R{sub b{bar b}} = 0.251 {plus minus} 0.049 {plus minus} 0.030, in good agreement with other measurements and the Standard Model prediction. 10 refs., 1 fig., 1 tab.
Download or read book A Measurement of the Branching Ratio of the Z Boson to Bottom Quarks Using Precision Tracking written by Robert Gibbs Jacobsen and published by . This book was released on 1991 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Measurement of Bottom Quark Production in Z Boson Hadronic Decays written by J. Coller and published by . This book was released on 2003 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A precise measurement of R{sub b}, the fraction of hadronic decays of the Z{sup 0} boson into bottom quark pairs, will test the Standard Model of particle physics. By measuring R{sub b}, the coupling between the Z{sup 0} boson and bottom quarks can be investigated. The strength of this coupling is sensitive to the top quark mass and to physics which lies outside the Standard Model. This thesis presents a measurement of R{sub b} made at the Stanford Linear Accelerator Center with the SLD experiment. Approximately 196,000 hadronic events are used in the measurement. The data set was obtained during the 1997-98 SLD physics run. The selection of B hadrons for identifying Z{sup 0} {yields} b{bar b} events is based on the invariant mass of topologically reconstructed vertices separated from the primary vertex for the event. This reconstruction method identifies B hadrons with a high efficiency (49.9%) and high purity (98.0%). Each candidate Z{sup 0} {yields} b{bar b} event is split into two separate hemispheres which are analyzed independently. The efficiency for tagging B hadrons is extracted from the data, reducing the dependence on the Monte Carlo simulation for B hadron and b quark systematic errors. A measured result of R{sub b} = 0.2185 {+-} 0.0013{sub (stat)} {+-} 0.0022{sub (syst.)} is reported. This value is consistent within measurement errors with the Standard Model prediction of 0.2158. The significant of this measurement is discussed.
Download or read book A Measurement of the Z Branching Fraction to Bottom Quarks written by Joel Goldstein and published by . This book was released on 1998 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Measurement of the Bottom Hadron Lifetime at the Z Sup 0 Resonancce written by and published by . This book was released on 1992 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the bottom hadron lifetime from b{bar b} events produced at the Z° resonance. Using the precision vertex detectors of the Mark II detector at the Stanford Linear Collider, we developed an impact parameter tag to identify bottom hadrons. The vertex tracking system resolved impact parameters to 30 [mu]m for high momentum tracks, and 70 [mu]m for tracks with a momentum of 1 GeV. We selected B hadrons with an efficiency of 40% and a sample purity of 80%, by requiring there be at least two tracks in a single jet that significantly miss the Z° decay vertex. From a total of 208 hadronic Z° events collected by the Mark II detector in 1990, we tagged 53 jets, of which 22 came from 11 double-tagged events. The jets opposite the tagged ones, referred as the untagged'' sample, are rich in B hadrons and unbiased in B decay times. The variable [Sigma][delta] is the sum of impact parameters from tracks in the jet, and contains vital information on the B decay time. We measured the B lifetime from a one-parameter likelihood fit to the untagged [Sigma][delta] distribution, obtaining [tau]{sub b} = 1.53{sub -0.45}{sup +0.55}{plus minus}0.16 ps which agrees with the current world average. The first error is statistical and the second is systematic. The systematic error was dominated by uncertainties in the track resolution function. As a check, we also obtained consistent results using the [Sigma][delta] distribution from the tagged jets and from the entire hadronic sample without any bottom enrichment.
Download or read book A Measurement of Bottom Quark Production in Z Boson Hadronic Decays written by John A. Coller and published by . This book was released on 2000 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
