Download or read book Measurement of the Charged Multiplicities of B C and Light Quark Events from Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately for[ital b, c] and light quark ([ital u, d, s]) events from Z[sup 0] decays at SLD. Impact parameters of charged tracks were used to select enriched samples of[ital b] and light quark events. We measured the charged multiplicities:[bar[ital n]][sub[ital uds]]= 19.80[+-] 0.09 ([ital stat])[+-] 0.57 ([ital syst]), [bar[ital n]][sub[ital c]]= 21.17[+-] 0.44 ([ital stat])[+-] 1.01 ([ital syst]) and[bar[ital n]][sub[ital b]][+-]23.14[+-] 0.09 ([ital stat])[+-] 1.03 ([ital syst]) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of[ital c] or[ital b] quark events and light quark events:[delta][bar[ital n]][sub[ital c]]= 1.37[+-] 0.45 ([ital stat])[+-] 0.86 ([ital syst]) and[delta][bar[ital n]][sub[ital b]]= 3.34[+-] 0. 13 ([ital stat])[+-] 0.77 ([ital syst]) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.
Download or read book Preliminary Measurement of the Charged Multiplicities in B C and Light Quark Events from Z Decays written by and published by . This book was released on 1996 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z° decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of b and light quark events, and reconstructed charmed mesons were used to select c quark events. We measured the charged multiplicities: {anti n}{sub uds} = 20.21 ± 0.10 (stat.) ± 0.17 (syst.), {anti n}{sub c} = 21.28 ± 0.46 (stat.){sub -0.33}{sup +0.38} (syst.) and {anti n}{sub b} = 23.14 ± 0.10 (stat.){sub -0.34}{sup +0.35} (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events: [Delta]{anti n}{sub c} = 1.07 ± 0.47 (stat.){sub -0.30}{sup +0.36} (syst.) and [Delta]{anti n}{sub b} = 2.93 ± 0.14 (stat.){sub -0.29}{sup +0.30} (syst.). We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.
Download or read book Preliminary Measurement of the Charged Multiplicities in B C and Light Quark Events from Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z[sup 0] decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of b and light quark events, and reconstructed charmed mesons were used to select c quark events. We measured the charged multiplicities:[anti n][sub uds]= 20.21[+-] 0.10 (stat.)[+-] 0.17 (syst.), [anti n][sub c]= 21.28[+-] 0.46 (stat.)[sub -0.33][sup+0.38] (syst.) and[anti n][sub b]= 23.14[+-] 0.10 (stat.)[sub -0.34][sup+0.35] (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events:[Delta][anti n][sub c]= 1.07[+-] 0.47 (stat.)[sub -0.30][sup+0.36] (syst.) and[Delta][anti n][sub b]= 2.93[+-] 0.14 (stat.)[sub -0.29][sup+0.30] (syst.). We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.
Download or read book Measurement of the Charged Multiplicities of B C and Light Quark Events from Z Decays written by and published by . This book was released on 1995 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately for {ital b, c} and light quark ({ital u, d, s}) events from Z° decays at SLD. Impact parameters of charged tracks were used to select enriched samples of {ital b} and light quark events. We measured the charged multiplicities: {bar {ital n}}{sub {ital uds}} = 19.80 ± 0.09 ({ital stat}) ± 0.57 ({ital syst}), {bar {ital n}}{sub {ital c}} = 21.17 ± 0.44 ({ital stat}) ± 1.01 ({ital syst}) and {bar {ital n}}{sub {ital b}}±23.14 ± 0.09 ({ital stat}) ± 1.03 ({ital syst}) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of {ital c} or {ital b} quark events and light quark events: [delta]{bar {ital n}}{sub {ital c}} = 1.37 ± 0.45 ({ital stat}) ± 0.86 ({ital syst}) and [delta]{bar {ital n}}{sub {ital b}} = 3.34 ± 0. 13 ({ital stat}) ± 0.77 ({ital syst}) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.
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 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 Measurement of the Charged Multiplicity of Bottom and Light Quark Events in E E Annihilation at s written by and published by . This book was released on 1997 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preliminary Measurement of Leading Particle Effects in Hadronic Z sup 0 Decays 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 preliminary evidence for leading particle production in hadronic decays of the Z[sup 0] to light quark pairs using 150,000 events recorded in the SLD experiment at SLAC. The highly polarized electron beam produced by the SLC is used to tag quark and antiquark jets, and a signed impact parameter technique is employed to reject heavy flavor events. Charged hadrons are identified in the SLD Cherenkov Ring Imaging Detector (CRID) and[Lambda]/[bar[Lambda]] are reconstructed using their charged decay modes. In a high purity sample of quark jets, the baryon momentum spectrum is harder that that of the antibaryon, and conversely for a sample of antiquark jets, supporting the hypothesis that the faster particles in jets are more likely to carry the primary quark or antiquark from the Z[sup 0] decay. Similarly, more high momentum K[sup -] that K[sup+] are observed in quark jets and conversely for antiquark jets, consistent with the hypothesis that leading K[sup[+-]] are produced predominantly in s[bar s] events rather than[ital u][bar[ital u]] events.
Download or read book Preliminary Measurement of Leading Particle Effects in Hadronic Z Decays 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 preliminary evidence for leading particle production in hadronic decays of the Z° to light quark pairs using 150,000 events recorded in the SLD experiment at SLAC. The highly polarized electron beam produced by the SLC is used to tag quark and antiquark jets, and a signed impact parameter technique is employed to reject heavy flavor events. Charged hadrons are identified in the SLD Cherenkov Ring Imaging Detector (CRID) and [Lambda]/{bar {Lambda}} are reconstructed using their charged decay modes. In a high purity sample of quark jets, the baryon momentum spectrum is harder that that of the antibaryon, and conversely for a sample of antiquark jets, supporting the hypothesis that the faster particles in jets are more likely to carry the primary quark or antiquark from the Z° decay. Similarly, more high momentum K− that K are observed in quark jets and conversely for antiquark jets, consistent with the hypothesis that leading K{sup {+-}} are produced predominantly in s{bar s} events rather than {ital u}{bar {ital u}} events.
Download or read book Measurement of the Charged Multiplicity of Z B bar B Events written by and published by . This book was released on 1994 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using an impact parameter tag to select an enriched sample of Z° --> b{bar b} events, the authors have measured the difference between the average charged multiplicity of Z° --> b{bar b} and Z° --> hadrons to be {bar n}{sub b} - {bar n}{sub had} = 2.24 " 0.30(stat.) " 0.33(syst.) tracks per event. From this, they have derived {bar n}{sub b} - {bar n}{sub uds} = 3.31 " 0.41 " 0.79. Comparing this measurement with those at lower center-of-mass energies, the authors find no evidence that {bar n}{sub b} - {bar n}{sub uds} depends on energy, in agreement with a precise prediction of perturbative QCD.
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 Search for the Production of ZW and ZZ Boson Pairs Decaying Into Charged Leptons and Jets in Proton antiproton Collisions at Sqrt s written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9 fb(̂-1) of integrated luminosity. We increase the sensitivity to vector boson decays into pairs of quarks using a neural network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be 2.5 +2.0 -1.0 pb (
Download or read book Physics Letters written by and published by . This book was released on 1997 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Event shape Observables in Z rightarrow ell ell Events in Pp Collisions at sqrt s written by and published by . This book was released on 2016 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Event-shape observables measured using charged particles in inclusive Z -boson events are presented, using the electron and muon decay modes of the Z bosons. The measurements are based on an integrated luminosity of 1.1 fb-1 of proton-proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy $$\sqrt{s}=7$$ TeV . Charged-particle distributions, excluding the lepton-antilepton pair from the Z -boson decay, are measured in different ranges of transverse momentum of the Z boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and F -parameter, which are in particular sensitive to properties of the underlying event at small values of the Z -boson transverse momentum. The measured observables are compared with predictions from Pythia 8, Sherpa, and Herwig 7. Furthermore, all three Monte Carlo generators provide predictions that are in better agreement with the data at high Z -boson transverse momenta than at low Z -boson transverse momenta, and for the observables that are less sensitive to the number of charged particles in the event.
Download or read book Measurements of Z and Z Production in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The production of Z bosons with one or two isolated high-energy photons is studied using pp collisions at √s=8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb-1 collected by the ATLAS detector during the 2012 LHC data taking. The Z? and Z?? production cross sections are measured with leptonic (e+e-, ?+?-, ?????????) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy ET > 250 GeV from l+l-? events and with ET > 400 GeV from ?????????? events are used to search for anomalous triple gauge-boson couplings ZZ? and Z??. The yields of events with diphoton invariant mass m?? > 200 GeV from l+l-?? events and with m?? > 300 GeV from ??????????? events are used to search for anomalous quartic gauge-boson couplings ZZ?? and Z???. As a result, no deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 1982 DPF Summer Study on Elementary Particle Physics and Future Facilities written by Rene Donaldson and published by . This book was released on 1982 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
